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USER'S GUIDE FOR THE
AMS/EPA REGULATORY MODEL -
AERMOD
EPA-454/B-03-001
September 2004
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USER'S GUIDE FOR THE
AMS/EPA REGULATORY MODEL -
AERMOD
U.S. Environmental Protection Agency
Office of Air Quality Planning and Standards
Emissions Monitoring and Analysis Division
Research Triangle Park, North Carolina
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NOTICE
Mention of trade names, products, or services does not convey, and should not be
interpreted as conveying official EPA approval, endorsement, or recommendation. The
following trademarks appear in this guide:
Compaq Visual Fortran is a registered trademark of Compaq Computer Corp.
IBM is a registered trademark of International Business Machines Corp.
Lahey LF95 is a registered trademark of Lahey Computer Systems, Inc.
80386, 80486, Pentium, and Pentium II are registered trademarks of Intel, Inc.
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PREFACE
This User's Guide for the AMS/EPA Regulatory Model (AERMOD) provides user
instructions for the AERMOD model. The technical description of the AERMOD algorithms
is provided in a separate document (EPA, 2004a). The revised AERMOD model described in
this user's guide includes the following modifications and enhancements: the PRIME
building downwash algorithms based on the ISC-PRIME model; use of allocatable arrays for
data storage; incorporation of EVENT processing for analyzing short-term source culpability;
post-1997 PM10 processing; a non-regulatory default TOXICS option that includes
optimizations for area sources and the Sampled Chronological Input Model (SCEVI) option;
explicit treatment of multiple-year meteorological data files and the ANNUAL average; and
options to specify emissions that vary by season, hour-of-day and day-of-week.
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ACKNOWLEDGMENTS
The User's Guide for AERMOD has been prepared by Pacific Environmental Services,
Inc., Research Triangle Park, North Carolina. This effort has been funded by the
Environmental Protection Agency (EPA) under Contract Nos. 68D30032 and 68D30001, with
Russell F. Lee as Work Assignment Manager (WAM), and under Contract No. 68D70069
with Warren D. Peters as WAM. The user instructions for AERMOD were developed in part
from Volume I of the ISC3 User's Guide (EPA, 1995).
IV
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CONTENTS
PREFACE iii
ACKNOWLEDGMENTS iv
FIGURES viii
TABLES ix
1.0 INTRODUCTION 1-1
1.1 HOW TO USE THE AERMOD MANUALS 1-1
1.1.1 Novice Users 1-1
1.1.2 Experienced Modelers 1-2
1.1.3 Management/Decision Makers 1-2
1.1.4 Programmers/Systems Analysts 1-3
1.2 OVERVIEW OF THE AERMOD MODEL 1-3
1.2.1 Regulatory Applicability 1-3
1.2.2 Basic Input Data Requirements 1-4
1.2.3 Computer Hardware Requirements 1-4
1.2.4 Overview of Available Modeling Options 1-5
2.0 GETTING STARTED - A BRIEF TUTORIAL 2-1
2.1 DESCRIPTION OF KEYWORD/PARAMETER APPROACH 2-1
2.1.1 Basic Rules for Structuring Input Runstream Files 2-2
2.1.2 Advantages of the Keyword Approach 2-5
2.2 REGULATORY MODELING OPTIONS 2-6
2.3 MODEL STORAGE LIMITS 2-7
2.4 SETTING UP A SIMPLE RUNSTREAM FILE 2-9
2.4.1 A Simple Industrial Source Application 2-11
2.4.2 Selecting Modeling Options - CO Pathway 2-11
2.4.3 Specifying Source Inputs - SO Pathway 2-15
2.4.4 Specifying a Receptor Network - RE Pathway 2-19
2.4.5 Specifying the Meteorological Input - ME Pathway 2-20
2.4.6 Selecting Output Options - OU Pathway 2-22
2.4.7 Using the Error Message File to Debug the Input Runstream File . . 2-26
2.4.8 Running the Model and Reviewing the Results 2-31
2.5 MODIFYING AN EXISTING RUNSTREAM FILE 2-38
2.5.1 Modifying Modeling Options 2-38
2.5.2 Adding or Modifying a Source or Source Group 2-38
2.5.3 Adding or Modifying a Receptor Network 2-39
2.5.4 Modifying Output Options 2-39
3.0 DETAILED KEYWORD REFERENCE 3-1
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3.1 OVERVIEW 3-1
3.2 CONTROL PATHWAY INPUTS AND OPTIONS 3-2
3.2.1 Title Information 3-2
3.2.2 Dispersion Options 3-2
3.2.3 Averaging Time Options 3-5
3.2.4 Urban Modeling Option 3-6
3.2.5 Specifying the Pollutant Type 3-7
3.2.6 Modeling With Exponential Decay 3-7
3.2.7 Flagpole Receptor Height Option 3-8
3.2.8 To Run or Not to Run - That is the Question 3-8
3.2.9 Generating an Input File for EVENT Processing 3-9
3.2.10 The Model Re-start Capability 3-10
3.2.11 Post-1997 PM10 Processing 3-11
3.2.12 Pre-1997 PM10 Processing 3-13
3.2.13 Debugging Output Option 3-14
3.2.14 Detailed Error Listing File 3-14
3.3 SOURCE PATHWAY INPUTS AND OPTIONS 3-15
3.3.1 Identifying Source Types and Locations 3-16
3.3.2 Specifying Source Release Parameters 3-17
3.3.3 Specifying Building Downwash Information
3-27
3.3.4 Specifying Urban Sources 3-32
3.3.5 Using Variable Emission Rates 3-33
3.3.6 Adjusting the Emission Rate Units for Output 3-36
3.3.7 Specifying Variables for Settling, Removal and Deposition Calculations
O O 'V
3-3 /
3.3.8 Specifying Variables for Precipitation Scavenging and Wet Deposition
Calculations 3-37
3.3.9 Specifying an Hourly Emission Rate File 3-37
3.3.10 Including Source Data From an External File 3-39
3.3.11 Using Source Groups 3-39
3.4 RECEPTOR PATHWAY INPUTS AND OPTIONS 3-41
3.4.1 Defining Networks of Gridded Receptors 3-41
3.4.2 Using Multiple Receptor Networks 3-49
3.4.3 Specifying Discrete Receptor Locations 3-49
3.4.4 Including Receptor Data From an External File 3-53
3.5 METEOROLOGY PATHWAY INPUTS AND OPTIONS 3-53
3.5.1 Specifying the Input Data Files and Formats 3-54
3.5.2 Specifying Station Information 3-56
3.5.3 Specifying the Base Elevation for Potential Temperature Profile . . 3-56
3.5.4 Specifying a Data Period to Process 3-57
3.5.5 Correcting Wind Direction Alignment Problems 3-59
3.5.6 Specifying Wind Speed Categories 3-60
3.5.7 Specifying SCIM Parameters 3-60
3.6 EVENT PATHWAY INPUTS AND OPTIONS 3-61
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3.6.1 Using Events Generated by the AERMOD Model 3-63
3.6.2 Specifying Discrete Events 3-64
3.6.3 Including Event Data From an External File 3-64
3.7 OUTPUT PATHWAY INPUTS AND OPTIONS 3-65
3.7.1 Selecting Options for Tabular Printed Outputs 3-65
3.7.2 Selecting Options for Special Purpose Output Files 3-68
3.7.3 EVENT Processing Options 3-79
3.8 CONTROLLING INPUT AND OUTPUT FILES 3-79
3.8.1 Description of AERMOD Input Files 3-80
3.8.2 Description of AERMOD Output Files 3-81
3.8.3 Control of File Inputs and Outputs (I/O) 3-88
4.0 REFERENCES 4-1
APPENDIX A. ALPHABETICAL KEYWORD REFERENCE A-l
APPENDIX B. FUNCTIONAL KEYWORD/PARAMETER REFERENCE B-l
APPENDIX C. EXPLANATION OF ERROR MESSAGE CODES C-l
C.I INTRODUCTION C-l
C.2 THE OUTPUT MESSAGE SUMMARY C-2
C.3 DESCRIPTION OF THE MESSAGE LAYOUT C-3
C.4 DETAILED DESCRIPTION OF THE ERROR/MESSAGE CODES C-5
APPENDIX D. DESCRIPTION OF FILE FORMATS D-l
D.I AERMET METEOROLOGICAL DATA D-l
D.2 THRESHOLD VIOLATION FILES (MAXIFILE OPTION) D-3
D.3 POSTPROCESSOR FILES (POSTFILE OPTION) D-3
D.4 HIGH VALUE RESULTS FOR PLOTTING (PLOTFILE OPTION) D-5
D.5 TOXX MODEL INPUT FILES (TOXXFILE OPTION) D-6
D.6 MAXIMUM VALUES BY RANK (RANKFILE OPTION) D-7
D.7 ARC-MAXIMUM VALUES FOR EVALUATION (EVALFILE OPTION) . D-8
D.8 RESULTS BY SEASON AND HOUR-OF-DAY (SEASONHR OPTION) . . D-9
APPENDIX E.
QUICK REFERENCE FOR AERMOD E-l
GLOSSARY GLOSSARY-1
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FIGURES
Figure
2-1. EXAMPLE INPUT FILE FOR AERMOD FOR SAMPLE PROBLEM 2-10
2-2. EXAMPLE INPUT RUNSTREAM FILE FOR SAMPLE PROBLEM 2-25
2-3. EXAMPLE MESSAGE SUMMARY TABLE FOR RUNSTREAM SETUP . . . 2-29
2-4. EXAMPLE OF KEYWORD ERROR AND ASSOCIATED MESSAGE
SUMMARY TABLE 2-30
2-5. ORGANIZATION OF AERMOD MODEL OUTPUT FILE 2-32
2-6. SAMPLE OF MODEL OPTION SUMMARY TABLE FROM AN AERMOD
MODEL OUTPUT FILE 2-35
2-7. EXAMPLE OUTPUT TABLE OF HIGH VALUES BY RECEPTOR 2-36
2-8. EXAMPLE OF RESULT SUMMARY TABLES FOR THE AERMOD MODEL 2-37
3-1. RELATIONSHIP OF AREA SOURCE PARAMETERS FOR ROTATED
RECTANGLE 3-23
3-2. SCHEMATIC DIAGRAM IDENTIFYING NEW BUILDING DATA FOR PRIME
DOWNWASH 3-31
C-l. EXAMPLE OF AN AERMOD MESSAGE SUMMARY C-3
Vlll
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TABLES
Table
3-1. SUMMARY OF SUGGESTED PROCEDURES FOR ESTIMATING INITIAL
LATERAL DIMENSIONS oyo AND INITIAL VERTICAL DIMENSIONS ozo FOR
VOLUME AND LINE SOURCES 3-20
B-l. DESCRIPTION OF CONTROL PATHWAY KEYWORDS B-2
B-2. DESCRIPTION OF CONTROL PATHWAY KEYWORDS AND
PARAMETERS B-3
B-3. DESCRIPTION OF SOURCE PATHWAY KEYWORDS B-6
B-4. DESCRIPTION OF SOURCE PATHWAY KEYWORDS AND
PARAMETERS B-7
B-5. DESCRIPTION OF RECEPTOR PATHWAY KEYWORDS B-10
B-6. DESCRIPTION OF RECEPTOR PATHWAY KEYWORDS AND
PARAMETERS B-l 1
B-7. DESCRIPTION OF METEOROLOGY PATHWAY KEYWORDS B-14
B-8. DESCRIPTION OF METEOROLOGY PATHWAY KEYWORDS AND
PARAMETERS B-15
B-9. DESCRIPTION OF EVENT PATHWAY KEYWORDS B-l7
B-10. DESCRIPTION OF EVENT PATHWAY KEYWORDS AND
PARAMETERS B-18
B-l 1. DESCRIPTION OF OUTPUT PATHWAY KEYWORDS B-19
B-12. DESCRIPTION OF OUTPUT PATHWAY KEYWORDS AND
PARAMETERS B-20
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1.0 INTRODUCTION
This section provides an overall introduction to the AERMOD model and to the
AERMOD user's guide. Some suggestions are offered on how various users would best
benefit from using the manuals. Also provided is an overview of the model's applicability,
range of options, and basic input data and hardware requirements. The input file needed to
run the AERMOD model is based on an approach that uses descriptive keywords and allows
for a flexible structure and format.
1.1 HOW TO USE THE AERMOD MANUALS
The AERMOD model user's guide has been designed in an attempt to meet the needs
of various types of users, depending on their level of experience with the model. This section
describes briefly how different types of users would benefit most from their use of the
manual.
1.1.1 Novice Users
Novice users are those whose exposure to or experience with the AERMOD model
has been limited. They may be new to dispersion modeling applications in general, or new to
the AERMOD model and therefore unfamiliar with the keyword/parameter approach utilized
for the input file. These users should review the remainder of this Introduction to gain an
overall perspective of the use of AERMOD model, particularly for regulatory modeling
applications. They should then concentrate their review on Section 2, which provides a brief
tutorial on setting up an input file that illustrates the most commonly used options of the
AERMOD model. Section 2 provides a basic description of the input file structure and
explains some of the advantages of the keyword/parameter approach to specifying modeling
options and inputs. As the user becomes more familiar with the operation of the model and
encounters the need to use more advanced features of the model, he/she will want to review
the contents of Section 3, which provides a more detailed and complete reference of the
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various options for running the model.
1.1.2 Experienced Modelers
Experienced modelers will have had considerable experience in applying the
AERMOD model in a variety of situations. They should have basic familiarity with the
overall goals and purposes of regulatory modeling in general, and with the scope of options
available in the AERMOD model in particular. Experienced modelers who are new to the
AERMOD model will benefit from first reviewing the contents of Section 2 of this volume,
which will give them a basic orientation to the structure, organization and philosophy of the
keyword/parameter approach used for the input runstream file. Once they have a basic grasp
of the input file structure and syntax rules, they will benefit most from using Section 3 of this
volume as a reference to learn the overall capabilities of the model, or to understand the
mechanics for implementing particular options. The information in Section 3 has a functional
organization with detailed descriptions of each of the individual keyword options by
functional pathway. Once they are familiar with most or all of the keywords, they may find
the functional keyword reference provided in Appendix B useful to quickly review the proper
syntax and available options/parameters for a particular keyword. They may also find the
Quick Reference available at the end of the user's guide sufficient as a simple reminder of the
available keywords for each pathway and to ensure the proper order of parameters for each
input image.
Experienced modelers may also need to refer to the description of model formulation
for AERMOD (EPA, 2000) in order to gain a more complete understanding of the technical
basis for the AERMOD model.
1.1.3 Management/Decision Makers
Those involved in a management or decision-making role for dispersion modeling
applications will be especially interested in the remainder of this section, which provides an
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overview of the model, including its role in various regulatory programs, a brief description
of the range of available options, and basic input data and computer hardware requirements
needed to run the model. From this information they should understand the basic capabilities
of the AERMOD model well enough to judge the suitability of the model for particular
applications. They may also want to review the brief tutorial provided in Section 2 to learn
about the nature and structure of the input runstream file, in order to better be able to review
the modeling results.
1.1.4 Programmers/Systems Analysts
Programmers and systems analysts, specifically those involved with installing the
AERMOD code on other computer systems or charged with maintaining the code, should
review the contents of Section 4 of this document. This will give specific details on
compiling and linking the code for various situations, and explain in detail the memory
storage requirements and control of input and output (I/O). They may also wish to review the
remainder of this Introduction and the brief tutorial in Section 2 of this volume in order to
have a basic understanding of the nature and overall capabilities of the model, and to
understand the basic input runstream file structure and organization.
1.2 OVERVIEW OF THE AERMOD MODEL
This section provides an overview of the AERMOD model, including a discussion of
the regulatory applicability of the model, a description of the basic options available for
running the model, and an explanation of the basic input data and hardware requirements
needed for executing the model.
1.2.1 Regulatory Applicability
The U.S. Environmental Protection Agency (EPA) maintains a Guideline on Air
Quality Models (hereafter, Guideline), which is published as Appendix W to 40 CFR Part 51
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(as revised). The Guideline provides the agency's guidance on regulatory applicability of air
quality dispersion models in general. In general, regulatory modeling applications should be
carried out in accordance with a modeling protocol that is reviewed and approved by the
appropriate agency prior to conducting the modeling. The modeling protocol should identify
the specific model, modeling options and input data to be used for a particular application.
1.2.2 Basic Input Data Requirements
One of the basic inputs to AERMOD is the runstream setup file which contains the
selected modeling options, as well as source location and parameter data, receptor locations,
meteorological data file specifications, and output options. Another type of basic type of
input data needed to run the model is the meteorological data. AERMOD requires two types
of meteorological data files, that are provided by the AERMET meteorological preprocessor
program (EPA, 2004b). One file consists of surface scalar parameters, and the other file
consists of vertical profiles of meteorological data. These meteorological data files are
described briefly later in this section, and in more detail in Sections 2 and 3. For applications
involving elevated terrain effects, the receptor and terrain data will need to be processed by
the AERMAP terrain preprocessing program (EPA, 2004c) before input to the AERMOD
model.
1.2.3 Computer Hardware Requirements
The current version of the AERMOD model was developed on an IBM-compatible
PC, and has been designed to run on PCs with an 80386 or higher central processing unit
(CPU) chip, a minimum of 2 MB of RAM, a math coprocessor, and MS-DOS Version 3.2 or
higher. In order to handle the input data files (runstream setup and meteorology) and the
output files, it is required that the system have a hard disk drive. The amount of storage space
required on the hard disk for a particular application will depend greatly on the output options
selected. Some of the optional output files of concentration data can be rather large. More
information on output file products is provided in Sections 2 and 3.
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1.2.4 Overview of Available Modeling Options
The AERMOD model includes a wide range of options for modeling air quality
impacts of pollution sources, making it a popular choice among the modeling community for
a variety of applications. The following sections provide a brief overview of the options
available in the AERMOD model.
1.2.4.1 Dispersion Options.
Since the AERMOD model is especially designed to support the EPA's regulatory
modeling programs, the regulatory modeling options will be the default mode of operation for
the model. These options include the use of stack-tip downwash, and a routine for processing
averages when calm winds or missing meteorological data occur. The model also includes
non-default options for suppressing the use of stack-tip downwash, and to disable the date
checking for non-sequential meteorological data files. The latter option is needed to facilitate
evaluation of the model. The user can specify several short term averages to be calculated in
a single run of the AERMOD model, as well as requesting the overall period (e.g. annual)
averages.
1.2.4.2 Source Options.
The model is capable of handling multiple sources, including point, volume, and area
source types. Line sources may also be modeled as a string of volume sources or as elongated
area sources. Several source groups may be specified in a single run, with the source
contributions combined for each group. This is particularly useful for PSD applications
where combined impacts may be needed for a subset of the modeled background sources that
consume increment, while the combined impacts from all background sources (and the
permitted source) are needed to demonstrate compliance with the National Ambient Air
Quality Standards (NAAQS). The model contain algorithms for modeling the effects of
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aerodynamic downwash due to nearby buildings on point source emissions. AERMOD does
include algorithms for modeling depositional effects on particulate emissions.
Source emission rates can be treated as constant throughout the modeling period, or
may be varied by month, season, hour-of-day, or other optional periods of variation. These
variable emission rate factors may be specified for a single source or for a group of sources.
The user may also specify a separate file of hourly emission rates for some or all of the
sources included in a particular model run.
1.2.4.3 Receptor Options.
The AERMOD model has considerable flexibility in the specification of receptor
locations. The user has the capability of specifying multiple receptor networks in a single
run, and may also mix Cartesian grid receptor networks and polar grid receptor networks in
the same run. This is useful for applications where the user may need a coarse grid over the
whole modeling domain, but a denser grid in the area of maximum expected impacts. There
is also flexibility in specifying the location of the origin for polar receptors, other than the
default origin at (0,0) in x,y, coordinates.
The user can input elevated receptor heights in order to model the effects of terrain
above (or below) stack base, and may also specify receptor elevations above ground level to
model flagpole receptors. There is no distinction in AERMOD between elevated terrain
below release height and terrain above release height, as with earlier regulatory models that
distinguished between simple terrain and complex terrain. For applications involving
elevated terrain, the user must also input a hill height scale along with the receptor elevation.
To facilitate the generation of hill height scales for AERMOD, a terrain preprocessor, called
AERMAP, has been developed (EPA, 2004c).
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1.2.4.4 Meteorology Options.
The AERMOD model utilizes a file of surface boundary layer parameters and a file of
profile variables including wind speed, wind direction, and turbulence parameters. These two
types of meteorological inputs are generated by the meteorological preprocessor for
AERMOD, which is called AERMET (EPA, 2004b). Both of these meteorological input files
are sequential ASCII files, and the model automatically recognizes the format generated by
AERMET as the default format. The model will process all available meteorological data in
the specified input file by default, but the user can easily specify selected days or ranges of
days to process.
1.2.4.5 Output Options.
The basic types of printed output available with AERMOD are:
• Summaries of high values (highest, second highest, etc.) by receptor for each
averaging period and source group combination;
• Summaries of overall maximum values (e.g., the maximum 50) for each
averaging period and source group combination; and
Tables of concurrent values summarized by receptor for each averaging period
and source group combination for each day of data processed. These "raw"
concentration values may also be output to unformatted (binary) files, as
described below.
The tables by receptor and maximum value tables can be output for the source group
values or for the individual source values, or both. In addition, when maximum values for
individual sources are output, the user has the option of specifying whether the maximum
source values are to be the maximum values for each source independently, or the
contribution of each source to the maximum group values, or both.
In addition to the tabular printed output products described above, the AERMOD
model provides options for several types of file output products. One of these options for
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AERMOD is to output an unformatted ("binary") file of all concentration values as they are
calculated. These files are often used for special postprocessing of the data. In addition to the
unformatted concentration files, AERMOD provides options for two additional types of file
outputs. One option is to generate a file of (X,Y) coordinates and design values (e.g., the
second highest values at each receptor for a particular averaging period and source group
combination) that can be easily imported into many graphics plotting packages to generate
contour plots of the concentration values. Separate files can be specified for all of the
averaging period and source group combinations of interest to the user.
Another output file option of the AERMOD model is to generate a file of all
occurrences when a concentration value equals or exceeds a user-specified threshold. Again,
separate files are generated for only those combinations of averaging period and source group
that are of interest to the user. These files include the date on which the threshold violation
occurred, the receptor location, and the concentration value.
AERMOD includes options for two types of output files that are designed to facilitate
model evaluation. One type of file lists concentrations by rank, where only one value per date
is included. This file may be used to generate Q-Q (quantile) plots of results, where values
from different models and/or observed data are paired by rank. The other type of output file
provides arc maxima results along with detailed information about the plume characteristics
associated with the arc maximum.
1.2.4.6 Source Contribution Analyses.
In air quality dispersion modeling applications, the user may have a need to know the
contribution that a particular source makes to an overall concentration value for a group of
sources. This section provides a brief introduction to how these types of source contribution
(sometimes referred to as source culpability) analyses are performed using the AERMOD
model. More detailed information about exercising these options is provided in Section 3.
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The AERMOD model provides the option of specifying source groups for which the
model calculates high values independently. However, users may often have to run the model
a second time selecting only specific days where the high values occurred, and setting up each
source in its own source group in order to obtain source contribution results. Rather than
running a separate EVENT model, as was done with ISCST2 (the original precursor to the
AERMOD model), the EVENT processing has been incorporated into the AERMOD model.
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2.0 GETTING STARTED - A BRIEF TUTORIAL
This section provides a brief tutorial for setting up a simple application problem with
the AERMOD model, which serves as an introduction for novice users to the AERMOD
model. The example illustrates the usage of the most commonly used options in the
AERMOD model. A more complete description of the available options for setting up the
AERMOD model is provided in Section 3.
The example problem presented in this section is a simple application of the
AERMOD model to a single point source. The source is a hypothetical stack at a small
isolated facility in a rural setting. Since the stack is below the Good Engineering Practice
(GEP) stack height, the emissions from the source are subject to the influence of aerodynamic
downwash due to the presence of nearby buildings. The tutorial leads the user through
selection and specification of modeling options, specification of source parameters, definition
of receptor locations, specification of the input meteorological data, and selection of output
options. Since this discussion is aimed at novice users of the AERMOD model, a general
description of the input file keyword/parameter approach is provided first.
2.1 DESCRIPTION OF KEYWORD/PARAMETER APPROACH
The input file for the AERMOD model makes use of a keyword/parameter approach to
specifying the options and input data for running the model. The descriptive keywords and
parameters that make up this input runstream file may be thought of as a command language
through which the user communicates with the model what he/she wishes to accomplish for a
particular model run. The keywords specify the type of option or input data being entered on
each line of the input file, and the parameters following the keyword define the specific
options selected or the actual input data. Some of the parameters are also input as descriptive
secondary keywords.
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The runstream file is divided into five functional "pathways." These pathways are
identified by a two-character pathway ID placed at the beginning of each runstream image.
The pathways and the order in which they are input to the model are as follows:
CO - for specifying overall job COntrol options;
SO - for specifying SOurce information;
RE - for specifying REceptor information;
ME - for specifying MEteorology information;
EV - for specifiying EVent processing;
OU - for specifying OUtput options.
Each line of the input runstream file consists of a pathway ID, an 8-character
keyword, and a parameter list. An example of a line of input from a runstream file, with its
various parts identified, is shown below:
The following sections describe the rules for structuring the input runstream file, and
explain some of the advantages of the keyword/parameter approach.
2.1.1 Basic Rules for Structuring Input Runstream Files
While the input runstream file has been designed to provide the user with considerable
flexibility in structuring the input file, there are some basic syntax rules that need to be
followed. These rules serve to maintain some consistency between input files generated by
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different users, to simplify the job of error handling performed by the model on the input data,
and to provide information to the model in the appropriate order wherever order is critical to
the interpretation of the inputs. These basic rules and the various elements of the input
runstream file are described in the paragraphs that follow.
One of the most basic rules is that all inputs for a particular pathway must be
contiguous, i.e., all inputs for the CO pathway must come first, followed by the inputs for the
SO pathway, and so on. The beginning of each pathway is identified with a "STARTING"
keyword, and the ending of the pathway with the "FINISHED" keyword. Thus the first
functional record of each input file must be "CO STARTING" and the last record of each
input file must be "OU FINISHED." The rest of the input images will define the options and
input data for a particular run.
Each record in the input runstream file is referred to as a runstream "image." These
records are initially read into the model as 132-character images. The information on each
input image consists of a "pathway," a "keyword," and one or more "parameters." Each of
these "fields" on the runstream image must be separated from other fields by at least one
blank space. To simplify the interpretation of the runstream image by the model, the
runstream file must be structured with the two-character pathway in columns 1 and 2, the
eight-character keyword in columns 4 through 11, followed by the parameters in columns 13
through 132, as necessary. For most keywords, the order of parameters following the
keyword is important — the exact spacing of the parameters is not important, as long as they
are separated from each other by at least one blank space and do not extend beyond the 132
character limit. The example of a runstream image from the CO pathway shown above is
repeated here:
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Alphabetical characters can be input as either lower case or upper case letters. The
model convert all character input to upper case letters internally, with the exception of the
title fields and file names to be discussed later. Throughout this document, the convention of
using upper case letters is followed. For numeric input data, it should be noted that all data
are assumed to be in metric units, i.e., length units of meters, speed units of meters per
second, temperature units of degrees Kelvin, and emission units of grams per second. In a
few instances, the user has the option of specifying units of feet for length and the model will
perform the conversion to meters. These exceptions are the input of receptor heights for
elevated terrain and the specification of anemometer height, since these values are often more
readily available in feet than in meters.
Certain keywords are mandatory and must be present in every runstream file, such as
the MODELOPT keyword shown in the example above which identifies the modeling
options. Other keywords are optional and are only needed to exercise particular options, such
as the option to allow for the input of flagpole receptor heights. Some of the keywords are
repeatable, such as the keywords to specify source parameters, while other keywords may
only appear once. The keyword references in Section 3, Appendices A and B and the Quick
Reference at the end of this volume identify each keyword as to its type, either mandatory or
optional, and either repeatable or non-repeatable.
With a few exceptions that are described below, the order of keywords within each
pathway is not critical. For the SO pathway, the LOCATION keyword must be specified
before other keywords for a particular source, and the SRCGROUP keyword must be the last
2-4
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keyword before SO FINISHED. For keywords on the SO pathway that accept a range of
source IDs, the source parameters specified by those keywords will only be applied to the
sources already defined, and will exclude any sources that are specified latter in the input file.
The PARAMETER ILEN_FLD is used to specify the maximum length of individual
fields on the input runstream image, and also to declare the length of all filename and format
variables. This PARAMETER is initially assigned a value of 80, and is in MODULE MAIN1
in MODULES.FOR.
2.1.2 Advantages of the Keyword Approach
The keyword approach provides some advantages over the type of input file used by
other models that require formatted input of several numeric switches. One advantage is that
the keywords are descriptive of the options and inputs being used for a particular run, making
it easier for a reviewer to ascertain what was accomplished in a particular run by reviewing
the input file. Another advantage is that the user has considerable flexibility in structuring the
inputs to improve their readability and understandability, as long as they adhere to the few
basic rules described above.
Some special provisions have been made to increase the flexibility to the user in
structuring the input files. One provision is to allow for blank records in the input file. This
allows the user to separate the pathways from each other, or to separate a group of images,
such as source locations, from the other images. Another provision is for the use of
"comment lines," identified by a "**" in the pathway field. Any input image that has "**" for
the pathway ID will be ignored by the model. This is especially useful for labeling the
columns in the source parameter input images, as illustrated in the example problem later in
this section. It may also be used to "comment out" certain options for a particular run without
deleting the options and associated data (e.g., elevated terrain heights) completely from the
input file. Because of the descriptive nature of the keyword options and the flexibility of the
2-5
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inputs it is generally much easier to make modifications to an existing input runstream file to
obtain the desired result.
Another reason for improved "user-friendliness" is that detailed error-handling has
been built into the model. The model provides descriptions of the location and nature of all of
the errors encountered for a particular run. Rather than stopping execution at each occurrence
of an input error, the model will read through and attempt to process all input records and
report all errors encountered. If a fatal error occurs, then the model will not attempt to
execute the model calculations.
2.2 REGULATORY MODELING OPTIONS
The regulatory default option is controlled from the MODELOPT keyword on the CO
pathway. As its name implies, this keyword controls the selection of modeling options. It is
a mandatory, non-repeatable keyword, and it is an especially important keyword for
understanding and controlling the operation of the AERMOD model. Unless specified
otherwise through the available keyword options, the AERMOD model implements the
following default options:
Use the elevated terrain algorithms requiring input of terrain height data;
Use stack-tip downwash (except for building downwash cases);
• Use the calms processing routines;
• Use the missing data processing routines;
Use a 4-hour half life for exponential decay of SO2 for urban sources.
The parameters used to specify options on the MODELOPT keyword are character strings,
called "secondary keywords," that are descriptive of the option being selected. For example,
to ensure that the regulatory default options are used for a particular run, the user would
include the secondary keyword "DFAULT" on the MODELOPT input. The presence of this
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secondary keyword tells the model to override any attempt to use a non-regulatory default
option. The model will warn the user if a non-regulatory option is selected along with the
DFAULT option, but will not halt processing. For regulatory modeling applications, it is
strongly suggested that the DFAULT switch be set, even though the model defaults to the
regulatory options without it. The MODELOPT keyword is described in more detail in the
Section 3.2.2.
For any application in which a non-regulatory option is to be selected, the DFAULT
switch must not be set, since it would otherwise override the non-regulatory option. The
non-regulatory options are also specified by descriptive secondary keywords; for example,
"NOSTD" invokes the option not to use stack-tip downwash.
2.3 MODEL STORAGE LIMITS
The AERMOD model has been designed using a dynamic storage allocation approach,
where the model allocates data storage as needed based on the number of sources, receptors,
source groups, and input requirements, up to the maximum amount of memory available on
the computer being used.
The AERMOD model uses dynamic arrays to allocate data storage at model runtime
rather than at compile time, as done by the previous version of AERMOD. The AERMOD
model preprocesses the model runstream input file to determine the data storage requirements
for a particular model run, and then allocates the input data arrays before processing the setup
data. Once the setup processing is completed, the model allocates storage for the result
arrays. When allocating data storage, the AERMOD model traps for errors, e.g., not enough
memory available to allocate. If the allocation is unsuccessful, then an error message is
generated by the model and further processing is prevented. If the CO RUNORNOT NOT
option is selected, the model will still go through all array allocations so that the user can
determine if sufficient memory is available to complete the run. Also, an estimate of the total
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amount of memory needed for a particular run is printed out as part of the first page of printed
output.
The parameters that are established at model runtime are as follows:
NSRC = Number of Sources
NREC = Number of Receptors
NGRP = Number of Source Groups
NAVE = Number of Short Term Averaging Periods
NVAL = Number of High Values by Receptor (RECTABLE Keyword)
NTYP = Number of Output Types (CONC currently is the only output type)
NMAX = Number of Overall Maximum Values (MAXTABLE Keyword)
NQF = Number of Variable Emission Rate Factors Per Source
NPDMAX = Number of Particle Diameter Categories Per Source
IXM = Number of X-coord (Distance) Values Per Receptor Network
IYM = Number of Y-coord (Direction) Values Per Receptor Network
NNET = Number of Cartesian and/or Polar Receptor Networks
NARC = Number of Receptor Arcs Used with EVALCART Keyword
NEVE = Number of Events for EVENT processing
In the case of NPDMAX, if no particle information is present in the input runstream, then
NPDMAX is set to 1, otherwise it is set to 20. Other parameters are set to the actual numbers
required for a particular model run.
There are several static array limits defined in AERMOD. These limits are controlled
by PARAMETER statements in the Fortran source code. The variable name, description, and
current value are defined in Section 4.2.2. If any of these static limits are changed, then
AERMOD must be recompiled and linked. This process is described in Section 4.2.1.
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2.4 SETTING UP A SIMPLE RUNSTREAM FILE
This section goes through a step-by-step description of setting up a simple application
problem, illustrating the most commonly used options of the AERMOD model. The example
problem is based on a simple industrial source application. The input file for AERMOD for
the example problem is shown in Figure 2-1. The remainder of this section explains the
various parts of the input file for the AERMOD model, and also illustrates some of the
flexibility in structuring the input file.
2-9
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CO
CO
CO
CO
CO
CO
CO
so
so
so
so
so
so
so
so
so
so
so
so
so
so
so
so
so
so
so
so
so
so
so
so
so
so
so
so
so
so
RE
RE
RE
RE
RE
RE
RE
ME
ME
ME
ME
ME
ME
ME
OF
OF
OF
OF
STARTING
TITLEONE
MODELOPT
AVERT IME
POLLUTID
RUNORNOT
FINISHED
STARTING
LOCATION
SRCPARAM
BUILDHGT
BUILDWID
BUILDWID
BUILDWID
BUILDWID
BUILDWID
BUILDWID
BUILDLEN
BUILDLEN
BUILDLEN
BUILDLEN
BUILDLEN
BUILDLEN
XBADJ
XBADJ
XBADJ
XBADJ
XBADJ
XBADJ
YBADJ
YBADJ
YBADJ
YBADJ
YBADJ
YBADJ
SRCGROUP
FINISHED
STARTING
GRIDPOLR
GRIDPOLR
GRIDPOLR
GRIDPOLR
GRIDPOLR
FINISHED
STARTING
SURFFILE
PROFFILE
SURFDATA
UAIRDATA
PROBATE
FINISHED
STARTING
RECTABLE
MAXTABLE
FINISHED
A Simple Example Problem for
CONC FLAT
3 24 PERIOD
S02
RUN
STACK1 POINT 0.0 0.0 0
STACK1 500.0 65.00 425.
STACK1 36
STACK1 62
STACK1 87
STACK1 89
STACK1 62
STACK1 87
STACK1 89
STACK1 82
STACK1 72
STACK1 86
STACK1 82
STACK1 72
STACK1 86
STACK1 -47
STACK1 -69
STACK1 -70
STACK1 -35
STACK1 -3
STACK1 -16
STACK1 34
STACK1 11
STACK1 -22
STACK1 -34
STACK1 -11
STACK1 22
ALL
POL1 STA
*50 .
.26 72
.58 82
.59 86
.26 72
.58 82
.59 86
.54 87
. 64 62
.51 89
.54 87
.64 62
.51 89
.35 -55
.21 -65
.07 -67
.19 -31
.43 3
.44 -22
.47 32
. 97 6
.50 -26
.47 -32
. 97 -6
.50 26
.64
.54
.51
. 64
.54
.51
.58
. 2 6
.59
. 58
. 2 6
.59
.76
. 60
.29
. 82
.34
.30
.89
.08
.81
.89
.08
.81
80
7 S
80
80
75
80
89
50
89
89
50
89
-62
-60
-62
-27
10
-27
30
0
-30
-30
0
30
the
0
15.
80
00
80
80
00
80
95
00
95
95
00
95
48
00
48
48
00
48
31
00
31
31
00
31
AERMOD-PRIME Model
0 5.
86
82
"7 9
86
82
72
89
62
87
89
62
87
-67
-65
-55
-22
3
-31
26
-6
-32
-26
6
32
51
54
64
51
54
64
59
2 6
58
59
2 6
58
29
60
76
30
34
82
81
08
89
81
08
89
89
87
62
89
87
62
86
72
82
86
72
82
-70
-69
-47
-16
-3
-35
22
-11
-34
-22
11
34
59
58
26
59
58
26
51
64
54
51
64
54
07
21
35
44
43
19
50
97
47
50
97
47
89
89
50
89
89
50
80
80
75
80
80
75
-70
-70
— 37
-10
-10
-37
17
-17
-35
-17
17
35
95
95
00
95
95
00
80
80
00
80
80
00
71
71
50
09
09
50
50
50
00
50
50
00
POL1 ORIG STACK1
POL1 DIST 175
POL1 GDIR 36
POL1 END
AERMET2.SFC
AERMET2.PFL
14735 1988
14735 1988
0.0 METERS
ALIVE FIRST
ALIVE 50
. 350. 500.
10 10
ALBANY ,
ALBANY ,
-SECOND
NY
NY
1000
FIGURE 2-1. EXAMPLE INPUT FILE FOR AERMOD FOR SAMPLE PROBLEM
2-10
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2.4.1 A Simple Industrial Source Application
For this simple tutorial, an application is selected involving a single point source of
SO2 that is subject to the influences of building downwash. The source consists of a 50-meter
stack with a buoyant release that is adjacent to a building. We will assume that the stack is
situated in flat terrain in a rural setting. A polar receptor network will be placed around the
stack location to identify areas of maximum impact.
2.4.2 Selecting Modeling Options - CO Pathway
The modeling options are input to the model on the Control pathway. The mandatory
keywords for the CO pathway are listed below. A complete listing of all keywords is
provided in Appendix B.
STARTING - Indicates the beginning of inputs for the pathway; this keyword is
mandatory on each of the pathways.
TITLEONE - A user-specified title line (up to 68 characters) that will appear on
each page of the printed output file (an optional second title line is
also available with the keyword TITLE TWO).
MODELOPT - Controls the modeling options selected for a particular run through a
series of secondary keywords.
AVERTIME - Identifies the averaging periods to be calculated for a particular run.
POLLUTID - Identifies the type of pollutant being modeled. At the present time,
this option has no influence on the results.
RUNORNOT - A special keyword that tells the model whether to run the full model
executions or not. If the user selects not to run, then the runstream
setup file will be processed and any input errors reported, but no
dispersion calculations will be made.
FINISHED - Indicates that the user is finished with the inputs for this pathway;
this keyword is also mandatory on each of the other pathways.
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The first two keywords are fairly self-explanatory. As discussed above in Section 2.2,
the MODELOPT keyword on the CO pathway is pivotal to controlling the modeling options
used for a particular run. For this example, we intend to use the regulatory default option, and
have specified for the model to output concentration values. After the first three input records
our input file will look something like this:
CO STARTING
CO TITLEONE A Simple Example Problem for the AERMOD-PRIME Model
CO MODELOPT CONC FLAT
Note that the title parameter field does not need to be in quotations, even though it represents
a single parameter. The model simply reads whatever appears in columns 13 through 80 of
the TITLEONE card as the title field, without changing the lower case to upper case letters.
Leading blanks are therefore significant if the user wishes to center the title within the field.
Note also that the spacing and order of the secondary keywords on the MODELOPT card are
not significant. A MODELOPT card that looked like this:
CO MODELOPT CONC FLAT
would have an identical result as the example above. It is suggested that the user adopt a
style that is consistent and easy to read. A complete description of the available modeling
options that can be specified on the MODELOPT keyword is provided in Section 3.
Since the pollutant in this example is SO2, we will probably need to calculate average
values for 3-hour and 24-hour time periods, and we also need to calculate averages for the full
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annual time period. Our runstream file might therefore look something like this after adding
two more keywords:
CO STARTING
CO TITLEONE A Simple Example Problem for the AERMOD-PRIME Model
CO MODELOPT CONG FLAT
CO AVERTIME 3 24 PERIOD
CO POLLUTID S02
Note again that the order of the parameters on the AVERTIME keyword is not critical,
although the order of the short term averages given on the AVERTIME keyword will also be
the order in which the results are presented in the output file. The order of the keywords
within each pathway is also not critical in most cases, although the intent of the input
runstream file may be easier to decipher if a consistent and logical order is followed. It is
suggested that users follow the order in which the keywords are presented in Section 3, in
Appendix B, and in the Quick Reference, unless there is a clear advantage to doing otherwise.
The only remaining mandatory keywords for the CO pathway are RUNORNOT and
FINISHED. We will set the RUNORNOT switch to RUN for this example. If a user is
unsure about the operation of certain options, or is setting up a complex runstream file to run
for the first time, it may be desirable to set the model NOT to run, but simply to read and
analyze the input file and report any errors or warning messages that are generated. Once the
input file has been debugged using these descriptive error/warning messages, then the
RUNORNOT switch can be set to RUN, avoiding a possible costly waste of resources
generating erroneous results. Even if the model is set NOT to run, all of the inputs are
summarized in the output file for the user to review.
Our complete runstream file for the CO pathway may look something like this:
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CO STARTING
CO TITLEONE A Simple Example Problem for the AERMOD-PRIME Model
CO MODELOPT CONC FLAT
CO AVERTIME 3 24 PERIOD
CO POLLUTID S02
CO RUNORNOT RUN
CO FINISHED
The following set of runstream images has a more structured look, but it is equivalent to the
example above:
CO STARTING
TITLEONE A Simple Example Problem for the AERMOD-PRIME Model
MODELOPT CONC FLAT
AVERTIME 3 24 PERIOD
POLLUTID S02
RUNORNOT RUN
CO FINISHED
Since the pathway ID is required to begin in column 1 (see Section 2.4.8 for a discussion of
this restriction), the model will assume that the previous pathway is in effect if the pathway
field is left blank. The model will do the same for blank keyword fields, which will be
illustrated in the next section.
In addition to these mandatory keywords on the CO pathway, the user may select
optional keywords to allow the use of receptor heights above ground-level for flagpole
receptors, to specify a decay coefficient or a half-life for exponential decay, and to generate
an input file containing events for EVENT processing. The user also has the option of having
the model periodically save the results to a file for later re-starting in the event of a power
failure or other interruption of the model's execution. These options are described in more
detail in Section 3 of this volume.
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2.4.3 Specifying Source Inputs - SO Pathway
Besides the STARTING and FINISHED keywords that are mandatory for all
pathways, the Source pathway has the following mandatory keywords:
LOCATION - Identifies a particular source ID and specifies the source type and
location of that source.
SRCPARAM - Specifies the source parameters for a particular source ID identified
by a previous LOCATION card.
SRCGROUP - Specifies how sources will be grouped for calculational purposes.
There is always at least one group, even though it may be the group of
ALL sources and even if there is only one source.
Since the hypothetical source in our example problem is influenced by a nearby building, we
also need to include the optional keywords BUILDHGT and BUILDWID in our input file.
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The input file for the SO pathway for this example will look something like this:
STARTING
LOCATION
SRCPARAM
BUILDHGT
BUILDHGT
BUILDHGT
BUILDHGT
BUILDHGT
BUILDHGT
BUILDWID
BUILDWID
BUILDWID
BUILDWID
BUILDWID
BUILDWID
BUILDLEN
BUILDLEN
BUILDLEN
BUILDLEN
BUILDLEN
BUILDLEN
XBADJ
XBADJ
XBADJ
XBADJ
XBADJ
XBADJ
YBADJ
YBADJ
YBADJ
YBADJ
YBADJ
YBADJ
SRCGROUP
FINISHED
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
ALL
There are a few things to note about these inputs. Firstly, the source ID (STACK 1 in
this example) is an alphanumeric parameter (up to eight characters) that identifies the inputs
for different keywords with a particular source. It is crucial that the source be identified with
a LOCATION card before any other keyword makes reference to that source, since this
identifies the source type (POINT in this case), and therefore which parameters the model will
allow. Besides POINT sources, the current version of the AERMOD model also allows
VOLUME and AREA sources to be specified. Since the effects of elevated terrain are
included in this analysis, it is important to specify the source base elevation above mean sea
level (MSL) on the LOCATION card. For this example, the source base elevation is 0.0
meters MSL.
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Another thing to note is that since the model uses direction-specific building
dimensions for all sources with downwash, there are 36 building heights and 36 building
widths entered on the appropriate keywords, one value for each 10 degree sector beginning
with the 10 degree flow vector (direction toward which the wind is blowing), and continuing
clockwise. Since the user could not fit all 36 values on a single record, the pathway, keyword
and source ID were repeated as many times as were necessary. In this case there were 6
values given on each of 6 lines for each of the building dimensions. There could have been
fewer or more lines as long as exactly 36 values were entered before starting with a new
keyword. Since all of the building heights were the same across the sectors (fairly realistic for
the height but not for widths, unless the structure was circular), there is a short cut available
for specifying numeric input in the runstream files for the model. The user can specify
"repeat values" by entering a field such as "36*50.0" as a parameter for the BUILDHGT
keyword. The model will interpret this as "36 separate entries, each with a value of 50.0,"
and store the values in the appropriate arrays within the model. Since the model must identify
this as a single parameter field, there must not be any spaces between the repeat-value and the
value to be repeated.
The final keyword before finishing the SO pathway must be the SRCGROUP
keyword. In this example, since there is only one source, we have taken advantage of a short
cut provided by the model by specifying a source group ID (which may be up to eight
characters) of ALL. Whenever this card appears in an input file, it will generate a source
group with a source-group ID of ALL, consisting of all sources defined for that run. The
sources do not have to be explicitly identified. In a run involving multiple sources, the user
may specify multiple source groups by repeating the SRCGROUP keyword. The use of the
SRCGROUP card is explained in more detail in Section 3.
2-17
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Using some of the formatting options discussed above, the SO pathway for our
example may look like this, with the same result as above:
SO STARTING
LOCATION
STACK1
** Point Source
** Parameters:
SRCPARAM STACK1
BUILDHGT
SO BUILDWID
SO BUILDLEN
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
SRCGROUP ALL
SO FINISHED
This version of the SO pathway inputs illustrates the use of the comment card to label the
stack parameters on the SRCPARAM card, i.e., QS for emission rate (g/s), HS for stack
height (m), TS for stack exit temperature (K), VS for exit velocity (m/s), and DS for stack
diameter (m). A complete description of the source parameter card, with a list of parameters
for each source type, is provided in Section 3.3 and in Appendix B.
Other optional inputs that may be entered on the SO pathway include specifying
variable emission rate factors for sources whose emissions vary as a function of month,
season, hour-of-day, or season and hour-of-day (see Section 3.3.4 for more details). The
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number of factors entered depends on the option selected, and factors may be input for single
sources or for a range of sources.
2.4.4 Specifying a Receptor Network - RE Pathway
As mentioned above, this example will illustrate the use of a single polar receptor
network centered on the stack location. Other options available on the REceptor pathway
include specifying a Cartesian grid receptor network, and specifying discrete receptor
locations in either a polar or a Cartesian system. These other options are described in more
detail in Section 3.4.
The RE pathway for this example will look like this:
RE STARTING
GRIDPOLR POL1 STA
GRIDPOLR POL1 ORIG STACK1
GRIDPOLR POL1 DIST 175. 350. 500. 1000.
GRIDPOLR POL1 GDIR 36 10 10
GRIDPOLR POL1 END
RE FINISHED
Looking at the example for the RE pathway, the first thing to note about these inputs is
that there is a new set of keywords, including something that looks like a STArting and
ENDing. In fact the GRIDPOLR keyword can be thought of as a "sub-pathway," in that all of
the information for a particular polar network must be in contiguous records, and that the
starting and ending of the sub-pathway are identified. The order of secondary keywords
within the sub-pathway is not critical, similar to the main pathways. Each card must be
identified with a network ID (up to eight alphanumeric characters), in this case it is "POLL"
Multiple networks may be specified in a single model run. The model waits until the END
secondary keyword is encountered to set the variables, which may include terrain heights for
receptors on elevated terrain or flagpole receptor heights if those options are being exercised
2-19
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by the user. The use of these optional secondary keywords is described in detail in Section
3.4.
For this example, the ORIG secondary keyword specifies the location of the origin for
the polar network being defined as being the location of the source STACK1. The origin can
also be specified as X and Y-coordinates. The ORIG keyword is optional, and the model will
default to an origin of (0.0, 0.0) if it is omitted. The DIST keyword identifies the distances
along each direction radial at which the receptors will be located. In this case there are four
distances. More distances could be added by adding values to that input card or by including
a continuation card with the DIST keyword, if needed. The GDIR keyword specifies that the
model will Generate DIRection radials for the network, in this case there will be 36 directions,
beginning with the 10 degree flow vector and incrementing every 10 degrees clockwise. The
user may elect to define Discrete DIRection radials instead by using the DDIR keyword in
place of the GDIR keyword.
2.4.5 Specifying the Meteorological Input - ME Pathway
The MEteorology pathway has the following four mandatory keywords (besides
STARTING and FINISHED, of course):
SURFFILE - Specifies the filename and format for the input surface meteorological
data file.
PROFFILE - Specifies the filename and format for the input profile meteorological
data file.
SURFDATA - Specifies information about the surface meteorological data which
will be used in the modeling.
UAIRDATA - Specifies information about the upper air meteorological data which
will be used in the modeling.
PROFB ASE - Specifies the base elevation above MSL for the potential temperature
profile.
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For the purposes of this example we will assume that the meteorological data files are for
Albany, NY and that an on-site location called Hudson has also been used. We will also
assume that the surface and profile data files were generated by the AERMET preprocessor,
and are in the default format for AERMOD. The filename of the surface file is
AERMET2.SFC and it consist of four days of data for Albany/Hudson from March 1988. The
filename of the profile file is AERMET2.PFL. The data files used in this example correspond
with the on-site example files used for the AERMET preprocessor program. The runstream
images for the MEteorology pathway would look something like this:
ME STARTING
SURFFILE AERMET2.SFC
PROFFILE AERMET2.PFL
SURFDATA 14735 1988 ALBANY, NY
UAIRDATA 14735 1988 ALBANY,NY
SITEDATA 99999 1988 HUDSON
PROFBASE 0.0 METERS
ME FINISHED
The first parameters on the SURFFILE and PROFFILE keywords are the filenames for
the surface and profile data file, respectively, which can be entered as a full DOS pathname,
including the drive specification and subdirectories, up to a total of 80 characters (with the
maximum number of characters controlled by the ILEN_FLD PARAMETER located in
MODULE MAIN1 - see Section 2.1.1). Since there is no second parameter, the model will
assume the default ASCII format for the data files. The format of the surface and profile data
files is described in Appendix D.
The next two mandatory inputs identify the location and data period of the input
meteorological data. A separate keyword is used for the surface meteorological data and for
the upper air (mixing height) data. The parameters on these cards are the station number (e.g.
WBAN number for NWS stations), the data period (year), and a station name. In order to
identify potential errors in the model inputs, the model compares the station number from the
runstream input file with values provided in the first record of the surface meteorology file,
and issues warning messages if there are any mismatches. The user may also optionally input
2-21
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the (X,Y) coordinates for the location of the station(s), although these values are not currently
used by the model. In this case, we have also included the optional SITED ATA keyword to
identify the location for the on-site meteorological data that were preprocessed by AERMET.
The final mandatory keyword is PROFBASE, which is used to specify the base
elevation (above MSL) for the potential temperature profile generated by AERMOD for use
in the plume rise calculations. This should correspond to the base elevation for the main
meteorological tower, which in this example is specified as 0.0 meters and is the same as the
source base elevation.
Other optional keywords available on the ME pathway provide the user with options
to specify selected days to process from the meteorological data file, and a wind direction
rotation correction term. These optional inputs are described in more detail in Section 3.5.
2.4.6 Selecting Output Options - OU Pathway
All of the keywords on the Output pathway are optional, although the model will warn
the user if no printed outputs are requested and will halt processing if no outputs (printed
results or file outputs) are selected. The user has considerable flexibility to select only the
outputs that are needed for a particular application. The printed table keywords are:
RECTABLE - Specifies the selection of high value by receptor table output options.
MAXTABLE - Specifies the selection of overall maximum value table output options.
DAYTABLE - Specifies the selection of printed results (by receptor) for each day of
data processed (this option can produce very large files and such be
used with care).
The RECTABLE keyword provides the highest, second-highest and third-highest
values by receptor. The MAXTABLE keyword provides the overall maximum 50 table. For
both of these keywords, the user has additional flexibility to specify for which short term
averaging periods the outputs are selected. For the MAXTABLE keyword the user can also
2-22
-------
specify the number of overall maximum values to summarize for each averaging period
selected, up to a maximum number controlled by a parameter in the computer code. For this
example problem we will select the highest and second-highest values by receptor, and the
maximum 50 values for all averaging periods. These OU pathway inputs will look something
like this:
OU STARTING
RECTABLE ALLAVE FIRST SECOND
MAXTABLE ALLAVE 50
OU FINISHED
To simplify the input for users who request the same printed table output options for
all averaging periods, these keywords recognize the secondary keyword "ALLAVE" as the
first parameter for that purpose. In order to obtain the overall maximum 10 values for the
24-hour averages only, then the OU pathway images would look like this:
OU STARTING
RECTABLE ALLAVE FIRST SECOND
MAXTABLE 24 10
OU FINISHED
It should also be noted that these output table options apply only to the short-term averaging
periods, such as the 3-hour and 24-hour averages used in our example. If the user has selected
that PERIOD averages be calculated (on the CO AVERTIME keyword), then the output file
will automatically include a table of period averages summarized by receptor (the
RECTABLE option does not apply since there is only one period value for each receptor). In
addition, the printed output file will include tables summarizing the highest values for each
averaging period and source group.
Other options on the OU pathway include several keywords to produce output files for
specialized purposes, such as generating contour plots of high values, identifying occurrences
2-23
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of violations of a particular threshold value (e.g. a NAAQS), and for postprocessing of the
raw concentration data. These options are described in detail in Section 3.7.
The complete input runstream file for this simple example is shown in Figure 2-2.
Note that a consistent style has been used for formatting and structuring the file in order to
improve its readability. This input file is comparable to the version shown earlier in Figure
2-1, which used a somewhat different style.
2-24
-------
CO
CO
so
•k ~k
STARTING
TITLEONE A Simple Example Problem for the
MODELOPT DFAULT CONG
AVERTIME 3 24 PERIOD
POLLUTID S02
RUNORNOT RUN
FINISHED
STARTING
LOCATION STACK1 POINT 0.0 0.0 0.0
Point Source QS HS TS VS
* * r CLJ_ CL1LL« L fci J_ ti i
SRCPARAM STACK1 500.
SO
SO
SO
SO
BUILDHGT
BUILDWID
BUILDLEN
XBADJ
YBADJ
STACK1 36*5
STACK1 62
STACK1 87
STACK1 89
STACK1 62
STACK1 87
STACK1 89
STACK1 82
STACK1 72
STACK1 86
STACK1 82
STACK1 72
STACK1 86
STACK1 -47
STACK1 -69
STACK1 -70
STACK1 -35
STACK1 -3
STACK1 -16
STACK1 34
STACK1 11
STACK1 -22
STACK1 -34
STACK1 -11
STACK1 22
0 65.0 425. 15.0
0.
.26 72.64
.58 82.54
.59 86.51
.26 72.64
.58 82.54
.59 86.51
.54 87.58
.64 62.26
.51 89.59
.54 87.58
.64 62.26
.51 89.59
.35 -55.76
.21 -65.60
.07 -67.29
.19 -31.82
.43 3.34
.44 -22.30
.47 32.89
.97 6.08
.50 -26.81
.47 -32.89
.97 -6.08
.50 26.81
80
75
80
80
75
80
89
50
89
89
50
89
-62
-60
-62
-27
10
-27
30
0
-30
-30
0
30
80
00
80
80
00
80
95
00
95
95
00
95
48
00
48
48
00
48
31
00
31
31
00
31
AERMOD Model
DS
5.0
86
82
72
86
82
"7 9
89
6 2
87
89
62
87
-67
-65
-55
-22
3
-31
26
-6
-32
-26
6
32
51
54
64
51
54
64
59
26
58
59
26
58
29
60
76
30
34
82
81
08
89
81
08
89
89
87
62
89
87
62
86
"7 9
82
86
72
82
-70
-69
-47
-16
-3
-35
22
-11
-34
-22
11
34
59
58
26
59
58
2 6
51
64
54
51
64
54
07
21
35
44
43
19
50
97
47
50
97
47
89
89
50
89
89
50
80
80
7 S
80
80
75
-70
-70
-37
-10
-10
-37
17
-17
-35
-17
17
35
95
95
00
95
95
00
80
80
00
80
80
00
71
71
50
09
09
50
50
50
00
50
50
00
SRCGROUP ALL
SO
RE
RE
ME
ME
OU
OU
FINISHED
STARTING
GRIDPOLR
GRIDPOLR
GRIDPOLR
GRIDPOLR
GRIDPOLR
FINISHED
STARTING
SURFFILE
PROFFILE
SURFDATA
UAIRDATA
SITEDATA
PROFBASE
FINISHED
STARTING
RECTABLE
MAXTABLE
FINISHED
POL1 STA
POL1 ORIG STACK1
POL1 DIST 175
POL1 GDIR 36
POL1 END
AERMET2.SFC
AERMET2.PFL
14735 1988
14735 1988
99999 1988
0.0 METERS
ALLAVE FIRS
ALLAVE 50
. 350. 500.
10 10
ALBANY , NY
ALBANY , NY
HUDSON
T SECOND
1000
FIGURE 2-2. EXAMPLE INPUT RUNSTREAM FILE FOR SAMPLE PROBLEM
2-25
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2.4.7 Using the Error Message File to Debug the Input Runstream File
The previous sections in this tutorial have lead through the step-by-step construction
of a sample runstream input file for AERMOD. This simple example problem illustrated the
usage of the most commonly used options of the AERMOD model. However, many real-time
applications of the model will be much more complex than this example, perhaps involving
multiple sources and source groups, multiple receptor networks, the addition of discrete
receptor locations, and/or elevated terrain heights. Since humans are prone to make errors
from time to time, an effort has been made to develop detailed error handling capabilities for
the AERMOD model.
The error handling capabilities of the AERMOD model are designed to accomplish
two things for the user. First, the model should read through the complete input file and
report all occurrences of errors or suspect entries before stopping, rather than stopping on the
first instance (and every instance thereafter) of an error in the input file. Second, the model
should provide error and warning messages that are detailed and descriptive enough that they
will help the user in his/her effort to debug the input file. The remainder of this section
provides of brief introduction to the use of the model's error handling capabilities. Appendix
C of this volume provides more details about the error handling provided by the AERMOD
model, including a listing and explanation of all error and other types of messages generated
by the model.
The AERMOD model generates messages during the processing of the input data and
during the execution of model calculations. These messages inform the user about a range of
possible conditions including:
Errors that will halt any further processing, except to identify additional error
conditions;
Warnings that do not halt processing but indicate possible errors or suspect
conditions; and
2-26
-------
• Informational messages that may be of interest to the user but have no direct
bearing on the validity of the results.
As the model encounters a condition for which a message is generated, the model
writes the message to a temporary storage file. At the completion of the setup processing for
a run, and at the completion of the model calculations, the model rereads the message file and
generates a summary of the messages which is included in the main printed output file. If the
processing of the model setup information indicates no errors or warnings, and the user has
selected the option to RUN the model calculations on the CO RUNORNOT card, then the
model will simply write a statement to the print file that the model setup was completed
successfully. Otherwise, the model will report a summary of the messages encountered. The
summary of model setup messages that would be generated for the example problem if the
option NOT to run was chosen is shown in Figure 2-3. This summary table reports the total
number of occurrences for each of the message types, and lists the detailed message for any
fatal errors or warning messages that were generated. In this case, since there were no errors
or suspicious conditions in the setup file, there are no error or warning messages listed.
An example of the warning message that would have been generated had we left out
the card on the RE pathway that specifies the origin of the polar receptor network is shown
below:
RE W220 39 REPOLR: Missing Origin (Use Default = 0,0) In GRIDPOLR
POL1
Hints
Detailed error/warning message
Subroutine from which message is generated
Line number of file where message occurred
Message code - including message type (E, W, I) and message number
Pathway ID where message originated
2-27
-------
Since this is a warning message, it would have appeared at the end of the message summary
table in the output file, but it would not have halted processing of the data. The last item on
the message line, "Hints," may include such information as the keyword or parameter name
causing the error, the source ID, group ID or (as in this case) the network ID involved, or
perhaps the date variable identifying when the message occurred during the processing of the
meteorological data, such as an informational message identifying the occurrence of a calm
wind.
For new users and for particularly complex applications, it is strongly recommended
that the model first be run with the RUNORNOT keyword (on the CO pathway) set NOT to
run. In this way, the user can determine if the model is being setup properly by the runstream
file before committing the resources to perform a complete run. The user should make a point
of examining any warning messages carefully to be sure that the model is operating as
expected for their application, since these messages will not halt processing by the model. In
most cases, the detailed messages will provide enough information for the user to determine
the location and nature of any errors in the runstream setup file. If the intent of the message is
not immediately clear, then the user should refer to the more detailed descriptions provided in
Appendix C for the particular error code generated.
In deciphering the error and warning messages, the line number provided as part of the
message may be particularly helpful in locating the error within the input file. However, if it
is an error of omission that is caught by the error checking performed at the completion of
inputs for a pathway, then the line number will correspond to the last record for that pathway.
The user may need to examine all of the messages carefully before locating the error or errors,
especially since a single occurrence of certain types of errors may lead to other error
conditions being identified later in the input file which do not really constitute errors in
themselves. An example of this is provided in Figure 2-4, which shows some inputs for the
SO pathway where the building dimension keywords have been typed incorrectly, and the
associated list of error messages. Since continuation cards were being used for the building
width inputs, and the keyword was entered incorrectly on the first line, the subsequent records
2-28
-------
were also taken by the model to be invalid keyword inputs. While the error messages are the
same for these records, the message originates from a different part of the model
(SUBROUTINE SOCARD) for the records with the blank keyword.
Since the detailed error and warning messages are listed in the output file as part of the
message summary table, there will generally not be a need for the user to examine the
contents of the detailed message file. For this reason, the default operation of the model is to
write the messages that are generated by a particular run to a temporary file that is deleted
when the run is completed. If the user wishes to examine the complete list of detailed
messages (of all types), there is an optional keyword available on the CO pathway for that
purpose. The ERRORFIL keyword, which is described in detail in Section 3.2.7, allows the
user to save the complete list of detailed messages to a user-specified filename.
*** Message Summary For AERMOD Model Setup ***
A Total of
A Total of
A Total of
t** FATAL ERROR MESSAGES
* * * NONE * * *
******** WARNING MESSAGES ********
* * * NONE * * *
FIGURE 2-3. EXAMPLE MESSAGE SUMMARY TABLE FOR RIMSTREAM SETUP
2-29
-------
so
STARTING
LOCATION STACK1 POINT 0.0 0.
Point Source QS HS TS
* * r CLJ_ cLiLLt; L « j_ ;D ;
SRCPARAM STACK1 500.0 65.0 425.
SO
*
A
A
A
SO
SO
SO
SO
SO
BUILDHTS STACK1 36
BUILDWTS STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
XBADJ STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
YBADJ STACK1
STACK1
STACK1
STACK1
STACK1
STACK1
SRCGROUP ALL
FINISHED
*50.
62.26
87.58
89.59
62.26
87.58
89.59
-47.35 -
-69.21 -
-70.07 -
-35.19 -
-3.43
-16.44 -
34.47
11.97
0 0.0
vs
0 15.0
72.64
82.54
86.51
72.64
82.54
86.51
-55.76 -
-65.60 -
-67.29 -
DS
5.
80
75
80
80
75
80
62
60
62
-31.82 -27
3.34
10
-22.30 -27
32.89
6.08
-22.50 -26.81 -
-34.47 -
-11.97
22.50
-32.89 -
-6.08
26.81
30
0
30
30
0
30
0
.80
.00
.80
.80
.00
.80
.48
.00
.48
.48
.00
.48
.31
.00
.31
.31
.00
.31
86.
82.
72.
86.
82.
72.
-67.
-65.
-55.
-22.
3.
-31.
26.
-6.
-32.
-26.
6.
32.
51
54
64
51
54
64
29
60
76
30
34
82
81
08
89
81
08
89
89.
87.
62.
89.
87.
62.
-70.
-69.
-47.
-16.
-3.
-35.
22.
-11.
-34.
-22.
11.
34.
59
58
26
59
58
26
07
21
35
44
43
19
50
97
47
50
97
47
89
89
50
89
89
50
-70
-70
-37
-10
-10
-37
17
-17
-35
-17
17
35
.95
.95
.00
.95
.95
.00
.71
.71
.50
.09
.09
.50
.50
.50
.00
.50
.50
.00
** Message Summary For AERMOD Model Setup ***
Total of 6 Fatal Error Message (s)
Total of 0
Total of 0
******** EATAL ERROR
E105 17 EXKEY : In
E105 18 EXKEY : In
Warning Message (s)
Information IX
MESSAGES ***
valid Keyworc
valid Keyworc
E105 19 SOCARD: Invalid Keyword
E105 20 SOCARD: In
valid Keyworc
E105 21 SOCARD: Invalid Keyword
******** WARNING MESSAGES ***
* * * NONE
********************
* * *
*************
*** SETUP Finishes UN-successfull
********************
*************
essage (s)
Specif iec
Specif iec
Specif iec
Specif iec
Specif iec
* * * * *
* * * * *
y ***
~k ~k ~k ~k ~k
The
The
The
The
The
Troubled Keyword
Troubled Ke
Troubled Ke
Troubled Ke
Troubled Ke
yword
yword
yword
yword
is
is
is
is
is
BUILDHTS
BUILDWTS
BUILDWTS
BUILDWTS
BUILDWTS
FIGURE 2-4. EXAMPLE OF KEYWORD ERROR AND ASSOCIATED MESSAGE
SUMMARY TABLE
2-30
-------
2.4.8 Running the Model and Reviewing the Results
Now that we have a complete and error-free runstream input file, we are ready to run
the model and then review the results. The PC-executable file available on the SCRAM
website opens the runstream input and printed output files explicitly within the model using
internally specified filenames of AERMOD.INP and AERMOD.OUT, respectively. The
model can be executed from the command prompt by simply typing the name AERMOD, as
follows:
C:\> AERMOD
The "c-prompt" of DOS has been represented by the characters "C:\>", but may appear
different on different machines. The important points are that the AERMOD.EXE file either
be in the directory from which you are attempting to run the model, or in a directory that is
included on the DOS PATH command when the system is "booted-up." The runstream input
file (AERMOD.INP) must also be located in the directory from which the model is being
executed. The model can also be executed by double clicking on the executable file from
Windows Explorer.
As mentioned above, the SCRAM PC-executable file for AERMOD opens the input
and output files explicitly. One reason for this is to allow for the model to write an update on
the status of processing to the PC terminal screen. For the AERMOD model, the model first
indicates that setup information is being processed and then gives the Julian day currently
being processed. If no status message is seen then the model did not load into memory
properly. If the model stops after completing the setup processing, then either the
RUNORNOT option was set NOT to run. If a fatal error is encountered during the setup
processing, then a message to that effect will be written to the screen and model execution
will be stopped. Another reason for not sending the printed output to the default output
device (i.e., to the screen or redirected to a file), is so that any DOS error messages will be
visible on the screen and not be written to the printed file. One such message might be that
2-31
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there is insufficient memory available to run the program. Handling of DOS error messages
may require some knowledge of DOS, unless the meaning of the message is obvious.
The order of contents and organization of the main output file for the AERMOD
model is presented in Figure 2-5.
Echo of Input Runstream Images
Summary of Runstream Setup Messages
Summary of Inputs
Summary of Modeling Options
Summary of Source Data
Summary of Receptor Data
Summary of Meteorology Data
Model Results
Daily Results for Each Averaging Period Selected for Each Day Processed (If
Applicable)
- DAYTABLE Keyword
PERIOD Results for Each Source Group (If Applicable)
- PERIOD Parameter on AVERTEVIE Keyword
Short Term Average Results (High, Second High, etc.) by Receptor for Each Source
Group (If Applicable)
- RECTABLE Keyword
Overall Maximum Short Term Average Results for Each Source Group (If
Applicable)
- MAXTABLE Keyword
Summary Tables of High Values for Each Averaging Period and Source Group (Always
provided if PERIOD averages or the RECTABLE keyword are used)
Summary of Complete Model Execution Messages
FIGURE 2-5. ORGANIZATION OF AERMOD MODEL OUTPUT FILE
2-32
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Each page of the output file, except for the echo of the input file images, is labeled with the
model name and version number, user-specified title(s), page number, and, for the PC version
of the model, the date and time of the particular run. Also included as part of the header
information for each page is a one-line summary of the modeling options used for that
particular run. The modeling options are listed as the secondary keywords used to control the
options, such as DFAULT, CONC, etc. (Details about the date/time routines and other PC-
specific features of the computer code are discussed in Section 4.0.)
Since the complete input file is normally echoed back as part of the output file, and
since processing of the inputs stops when the OU FINISHED card is reached, the run can be
duplicated by simply specifying the output filename as the input runstream file. Alternatively,
the input records could be "cut and pasted" from the output file to a separate file using a text
editor.
By default, the model will echo each line of the input runstream file to the printed
output file. This provides a convenient record of the inputs as originally read into the model,
without any rounding of numerical values that may appear in the input summary tables. As
noted above, it also means that the output file can be used as an input file to the model to
reproduce a particular application. However, for some applications, the length of the input
runstream file may be too cumbersome to include the entire set of inputs at the beginning of
each output file. This may happen, for example, if a large number of sources are being
defined or if a large number of discrete receptor locations are used. For this reason, the user
is provided with the option to "turn off" the echoing of the input file at any point within the
runstream file. This is accomplished by entering the keywords "NO ECHO" in the first two
fields anywhere within the runstream file. In other words, place NO in the pathway field,
followed by a space and then ECHO. None of the input runstream images after the NO
ECHO will be echoed to the output file. Thus, a user may choose to place NO ECHO after
the Control pathway in order to keep the control options echoed, but suppress echoing the rest
of the input file.
2-33
-------
The details of the message summary tables were discussed in the previous section. A
portion of the summary of modeling option inputs is shown in Figure 2-6 for the simple
example described in this section. The summary of source parameter input data includes
separate tables for each source type, rather than combining all sources onto a single table. In
this way the column headings are specific to the source type.
Figure 2-7 presents an example of the results output for the second highest values by
receptor for our sample problem. These values are the second highest 3-hour averages at each
receptor location. The number in parentheses following each concentration value is the date
corresponding to each value. The date is given as an eight digit integer variable that includes
the year (2-digits), month, day, and hour corresponding to the end of the averaging period.
For each of the different types of model result tables, the controlling keyword is
identified in Figure 2-5 at the end of the description. All of the outputs of the same type, e.g.
high values by receptor, are printed together, and the order of tables loops through all source
groups for a particular averaging period, and then loops through all averaging periods. The
summary tables of high values at the end of the model results follow the same order of loops.
An example of the summary tables for our sample problem is shown in Figure 2-8. The
summaries for all averaging periods have been combined onto a single figure, but would
appear on separate pages of the actual output file.
2-34
-------
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*** AERMOD - VERSION 04209 *** *** A Simple Example Problem for the AERMOD Model with PRIME *** 09/13/04
*** *** 15:40 :59
**MODELOPTs: PAGE 10
CONC FLAT
*** THE 2ND HIGHEST 3-HR AVERAGE CONCENTRATION VALUES FOR SOURCE GROUP: ALL ***
(INCLUDING SOURCE (S): STACKl
*** NETWORK ID: POLl ; NETWORK TYPE: GRIDPOLR ***
** CONC OF SO2 IN MICROGRAMS/M* * 3 **
DISTANCE (METERS)
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2.5 MODIFYING AN EXISTING RUNSTREAM FILE
As noted earlier, one of the advantages of the keyword/parameter approach and the
flexible format adopted for the input runstream file is that it will be easier for the user to make
modifications to the runstream file and obtain the desired result. This section briefly illustrates
some examples of how a runstream file can be modified. It is assumed that the reader is familiar
with the operation of and basic editing commands for a text editor (i.e., a program that edits
ASCII files), and is familiar with the previous sections of this tutorial.
2.5.1 Modifying Modeling Options
Depending on the type of analysis being performed, the user may need to modify the
modeling options and run the model again. Because of the descriptive nature of the keywords and
the secondary keywords used to control the modeling options, this can easily be done with the
new runstream file, and usually without having to refer back to the user's guide each time a
modification is attempted.
2.5.2 Adding or Modifying a Source or Source Group
Modifying the input file to add a source or a source group, or to add a source to a source
group, is as simple as just adding it. There is no need to specify the total number of sources in the
run, which would then have to be changed if more sources were added. The same applies to the
number of groups, or the number of sources per group. If the user attempts to input more than the
total number of sources or groups allowed for a particular run, an error message will be generated
to that effect. Also, modifying a source group to delete a source is as easy as just deleting it from
the input card, without having to change any other inputs.
Another way of "deleting" a source or a group from an input file is to place a "**" in the
pathway field of the card or cards which define the source or group to "comment out" those
inputs. This approach, which was discussed above in Section 2.1.2, has the advantage of leaving
the input data for the source or group in the input file for possible later use. It doesn't matter
2-38
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whether the "**" is entered with the text editor in "insert" mode, in which case the other inputs of
that line are moved over, or if it is in "overtype" mode, which would replace the pathway ID that
was already there.
2.5.3 Adding or Modifying a Receptor Network
As with source data, adding to or modifying the receptor information in the AERMOD
model is relatively straight forward. The problem of having to make several changes to
accomplish one small modification, such as adding a distance to a polar receptor network, has
been avoided in the new model. All that the user needs to do is to add the new distance on the
appropriate input card, which is easily identifiable because of the use of descriptive keywords.
The model checks to ensure that the user does not attempt to specify more than the maximum
number of receptors for a particular run, and generates an appropriate message if too many are
input.
2.5.4 Modifying Output Options
Modifying the output options involves many of the same principles that are described
above. In addition, all of the output options are structured in a way that allows the user to select
options for specific averaging periods, so that the user may find it useful to copy a record or
group of records set up for one averaging period and simply change the averaging period
parameter. The other important short cut that is available for the printed table output options is to
use the secondary keyword ALLAVE to indicate that the option applies to all averaging periods
that are calculated. In this way, there will be no need to change the output options if a new
averaging period is added to a run or if one is deleted.
2-39
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3.0 DETAILED KEYWORD REFERENCE
This section of the AERMOD User's Guide provides a detailed reference for all of the
input keyword options for the AERMOD model. The information provided in this section is more
complete and detailed than the information provided in the Brief Tutorial in Section 2. Since this
section is intended to meet the needs of experienced modelers who may need to understand
completely how particular options are implemented in the model, the information for each
keyword should stand on its own. This section assumes that the reader has a basic understanding
of the keyword/parameter approach used by the model for specification of input options and data.
Novice users should first review the contents of Section 2 in order to obtain that understanding.
3.1 OVERVIEW
The information in this section is organized by function, i.e., the keywords are grouped by
pathway, and are in a logical order based on their function within the model. The order of
keywords presented here is the same as the order used in the functional keyword reference in
Appendix B, and the Quick Reference section at the end of the volume. The syntax for each
keyword is provided, and the keyword type is specified - either mandatory or optional and either
repeatable or non-repeatable. Unless noted otherwise, there are no special requirements for the
order of keywords within each pathway, although the order in which the keywords are presented
here and in Appendix B is recommended. Any keyword which has special requirements for its
order within the pathway is so noted following the syntax and type description.
The syntax descriptions in the following sections use certain conventions. Parameters that
are in all capital letters and underlined in the syntax description are secondary keywords that are
to be entered as indicated for that keyword. Other parameters are given descriptive names to
convey the meaning of the parameter, and are listed with an initial capital letter. Many of the
parameter names used correspond to variable names used in the computer code of the model.
Parentheses around a parameter indicate that the parameter is optional for that keyword. The
default that is taken when an optional parameter is left blank is explained in the discussion for
that keyword.
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3.2 CONTROL PATHWAY INPUTS AND OPTIONS
The COntrol pathway contains the keywords that provide the overall control of the model
run. These include the dispersion options, averaging time options, terrain height options, and
others that are described below. The CO pathway must be the first pathway in the runstream
input file.
3.2.1 Title Information
There are two keywords that allow the user to specify up to two lines of title information
that will appear on each page of the main output file from the model. The first keyword,
TITLEONE, is mandatory, while the second keyword, TITLETWO, is optional. The syntax and
type for the keywords are summarized below:
Syntax:
CO TITLEONE Titlel
CO TITLETWO Title2
TITLEONE - Mandatory, Non-repeatable
TITLETWO - Optional, Non-repeatable
The parameters Titlel and Title2 are character parameters of length 68, which are read as a single
field from columns 13 to 80 of the input record. The title information is taken as it appears in the
runstream file without any conversion of lower case to upper case letters. If the TITLETWO
keyword is not included in the runstream file, then the second line of the title in the output file
will appear blank.
3.2.2 Dispersion Options
The dispersion options are controlled by the MODELOPT keyword on the CO pathway.
The syntax, type, and order of the MODELOPT keyword are summarized below:
Syntax:
CO MODELOPT DFAULT CONG FLAT NOSTD NOCHKD NOWARN SCREEN TOXICS SCIM
Type:
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where the secondary keyword parameters are described below (the order and spacing of these
parameters is not critical):
DFAULT - Specifies that the regulatory default options will be used;
CONC - Specifies that concentration values will be calculated (note that deposition
algorithms have not been implemented in AERMOD yet);
FLAT - Specifies that the non-default option of assuming flat terrain will be used;
NOSTD - Specifies that the non-default option of no stack-tip downwash will be
used;
NOCHKD - Specifies that the non-default option of suspending date checking will be
used for non-sequential meteorological data files;
NOWARN - Specifies that the option of suppressing the detailed listing of warning
messages in the main output file will be used (the number of warning
messages is still reported, and warning messages are still included in the
error file controlled by the CO ERRORFIL card described in Section
3.2.14);
SCREEN - Specifies that the non-default option for running AERMOD in a screening
mode will be used;
TOXICS - Specifies use of air toxics option(s), including SCIM and area source
optimizations; and
SCIM - Sampled Chronological Input Model - used only with the ANNUAL
average option to reduce runtime by sampling meteorology at a user-
specified regular interval; SCIM sampling parameters must be specified on
the ME pathway.
The regulatory default option in AERMOD includes the use of stack-tip downwash,
incorporates the effects of elevated terrain, and includes the calms and missing data processing
routines. The regulatory default option in AERMOD also forces the use of a 4-hour half life
when modeling SO2 in an urban source, and does not allow for exponential decay for other
applications.
The missing data processing routines that are included in the AERMOD model allow the
model to handle missing meteorological data in the processing of short term averages. The model
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treats missing meteorological data in the same way as the calms processing routine, i.e., it sets the
concentration values to zero for that hour, and calculates the short term averages according to
EPA's calms policy, as set forth in the Guideline. Calms and missing values are tracked
separately for the purpose of flagging the short term averages. An average that includes a calm
hour is flagged with a 'c', an average that includes a missing hour is flagged with an 'm', and an
average that includes both calm and missing hours is flagged with a 'b'. If the number of hours of
missing meteorological data exceeds 10 percent of the total number of hours for a given model
run, a cautionary message is written to the main output file, and the user is referred to Section
5.3.2 of "Meteorological Monitoring Guidance for Regulatory Modeling Applications" (EPA,
2004 ).
The screening mode of AERMOD, which is controlled by the SCREEN keyword on the
MODELOPT card, forces the model calculations to represent values for the plume centerline,
regardless of the source-receptor-wind direction orientation. This option is included in
AERMOD to facilitate the use of the model with a Windows-based AERMOD Screening Model
interface (not yet developed) to estimate worst case impacts. Its use outside of that context is not
recommended. Since the screening model is designed to be used with a non-sequential
meteorological data file, representing a matrix of conditions, the SCREEN option also forces the
use of the NOCHKD option described above, even if NOCHKD is not included on the
MODELOPT card. The SCREEN option also restricts the averaging period options to 1-hour
averages only on the AVERTIME card (see Section 3.2.3).
The AERMOD model includes the Sampled Chronological Input Model (SCEVI) option
for air toxics applications. In order to utilize this option, the user must include the TOXICS and
SCIM keywords together on the CO MODELOPT card. Since the TOXICS option is a non-
regulatory default option, the DFAULT keyword should not be included on the MODELOPT
card. If the DFAULT keyword is present on the MODELOPT card, the DFAULT option will
override the TOXICS option if it is present, and any other enhancements dependent on the
TOXICS option. The SCEVI approach associated with the TOXICS option is described below.
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When the TOXICS option is specified, the area source integration routine is optimized to
reduce model runtime. This is accomplished by incorporation of a three-tiered approach using the
Romberg numerical integration, a 2-point Gaussian Quadrature routine for numerical integration,
or a point source approximation based on the location of the receptor relative to the source. In the
regulatory default mode the Romberg numerical integration is utilized for all receptors.
If the non-default TOXICS option is specified, the user may also use the SCIM option to
reduce model runtime. The SCIM option can only be used with the ANNUAL average option,
and is primarily applicable to multi-year model simulations. The approach used by the SCIM
option is to sample the meteorological data at a user-specified regular interval to approximate the
long-term (i.e., ANNUAL) average impacts. Studies have shown that the uncertainty in modeled
results introduced by use of the SCIM option is generally lower for area sources than for point
sources.
When only the regular sampling is selected, hourly concentrations are calculated in the
normal fashion for each sampled hour. The annual average concentration is then simply
calculated by dividing the cumulative concentration for the sampled hours by the number of hours
sampled (arithmetic average), i.e.,
C=XCS/NS
where:
C = Calculated concentration
V Cs = Cumulatibe impacts for the sampled hours
Ns = Number of sampled hours
To use the SCIM option, the user must include the SCIM and TOXICS keywords on the
CO MODELOPT card, and also specify the SCIM sampling parameters on the ME SCIMBYHR
card. The format and syntax of the ME SCIMBYHR keyword are described in Section 3.5.7.
3.2.3 Averaging Time Options
The averaging periods for AERMOD are selected using the AVERTEVIE keyword. The
syntax and type of the AVERTIME keyword are summarized below:
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Syntax:
CO AVERTIME Timel Time2 Time3 Time4 MONTH PERIOD
Type:
Mandatory, Non-repeatable
where the parameters Timel . . . Time4 refer to the user-specified short term averaging periods of
1, 2, 3, 4, 6, 8, 12, or 24 hours, the secondary keyword MONTH refers to monthly averages (for
calendar months), and the secondary keyword PERIOD refers to the average for the entire data
period. Any of the short term averaging periods listed above may be selected for a given run, as
long as the total data storage needed by the model does not exceed the available computer
memory. Since the monthly averages are treated as short term averages, the user can select
appropriate output options, such as the second highest values by receptor, on the OUtput pathway.
The location of the PERIOD keyword in the parameter list is not critical. The order of the
short term averaging periods (including MONTH) is also not critical, although it does control the
order of the averaging period result tables in the main output file. Generally, it is recommended
that the short term averaging periods be input in increasing order, unless there is a clear advantage
in doing otherwise.
3.2.4 Urban Modeling Option
The AERMOD model allows the user to incorporate the effects of increased surface
heating from an urban area on pollutant dispersion under stable atmospheric conditions. The user
defines the input parameters for the urban area with the URBANOPT keyword on the CO
pathway, and then identifies which sources are to be modeled with urban effects using the
URBANSRC keyword on the SO pathway (see Section 3.3.4). The syntax and type of the
URB ANOPT keyword are summarized below:
Syntax:
Type:
Optional, Non-repeatable
where the UrbPop parameter specifies the population of the urban area, the optional UrbName
parameter may be used to identify the name of the urban area, and the optional UrbRoughness
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parameter may be used to specify the urban surface roughness length. Note the UrbName must be
specified if the user wants to specify the urban roughness length. A default value of 1.0 meter
will be used for the urban roughness length if the UrbRoughness parameter is omitted.
3.2.5 Specifying the Pollutant Type
The POLLUTID keyword is used to identify the type of pollutant being modeled for a
particular run. The syntax, type, and order of the POLLUTID keyword are summarized below:
Syntax:
CO POLLUTID Pollut
Type: Mandatory, Non-repeatable
where the Pollut parameter may be name of up to eight characters. Examples include SO2. NOX,
CO. PM10. TSP. and OTHER. The only choice that currently has any impact on the results is the
selection of PM10 (or PM-10) with the multi-year option for generating the high-sixth-high in
five years. Otherwise, the pollutant ID currently has no effect on the calculations made in
AERMOD.
3.2.6 Modeling With Exponential Decay
The model provides the option to use exponential decay of the pollutant being modeled.
Two keywords are available for this purpose, the HALFLIFE and DCAYCOEF keywords. The
syntax, type, and order of these keywords are summarized below:
Syntax:
CO HALFLIFE Haflif
CO DCAYCOEF Decay
Type:
Optional, Non-repeatable
where the Haflif parameter is used to specify the half life for exponential decay in seconds, and
the parameter Decay is used to specify the decay coefficient in units of s"1. The relationship
between these parameters is DECAY = 0.693/HAFLIF.
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Only one of these keywords may be specified in a given run. If more than one is
encountered, a non-fatal warning message is generated and the first specification is used in the
modeling.
3.2.7 Flagpole Receptor Height Option
The FLAGPOLE keyword specifies that receptor heights above local ground level (i.e.
flagpole receptors) are allowed on the REceptor pathway. The FLAGPOLE keyword may also be
used to specify a default flagpole receptor height other than 0.0 meters. The syntax and type of
the FLAGPOLE keyword are summarized below:
Syntax:
CO FLAGPOLE (Flagdf)
Type:
Optional, Non-repeatable
where Flagdf is an optional parameter to specify a default flagpole receptor height. If no
parameter is provided, then a default flagpole receptor height of 0.0 meters is used. Any flagpole
receptor heights that are entered on the Receptor pathway will override the default value, but are
ignored if the FLAGPOLE keyword is not present on the Control pathway, and a non-fatal
warning message is generated.
3.2.8 To Run or Not to Run - That is the Question
Because of the improved error handling and the "defensive programming" that has been
employed in the design of the AERMOD model, it is intended that the model will read through all
of the inputs in the runstream file regardless of any errors or warnings that may be encountered.
If a fatal error occurs in processing of the runstream information, then further model calculations
will be aborted. Otherwise, the model will attempt to run. Because of the great many options
available in the AERMOD model, and the potential for wasted resources if a large run is
performed with some incorrect input data, the RUNORNOT keyword has been included on the
Control pathway to allow the user to specify whether to RIM the model and perform all of the
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calculations, or NOT to run and only process the input runstream data and summarize the setup
information. The syntax and type of the RUNORNOT keyword are summarized below:
Syntax:
Type:
Mandatory, Non-repeatable
3.2.9 Generating an Input File for EVENT Processing
The AERMOD model contains the EVENTFIL keyword on the CO pathway to control
whether or not the AERMOD model will generate an input file for EVENT processing. The
syntax and type of the EVENTFIL keyword are summarized below:
Syntax:
CO EVENTFIL (Evfile) (Evopt)
Type:
Optional, Non-repeatable
where the optional Evfile parameter specifies the name of the EVENT input file to be generated
(the maximum length of the file name is set by the ILEN_FLD parameter in MODULE MAIN1),
and the optional parameter, Evopt, specifies the level of detail to be used in the EVENT output
file. Valid inputs for the Evopt parameter are the secondary keywords of SOCONT and DETAIL
(see the EVENTOUT keyword on the OUtput pathway, Section 3.7.2). The default filename used
if no parameters are specified is EVENTS.INP, and the default for the level of detail is DETAIL.
If only one parameter is present, then it is taken to be the Evfile, and the default will be used for
Evopt.
The primary difference between routine AERMOD and EVENT processing is in the
treatment of source group contributions. The AERMOD model treats the source groups
independently. EVENT processing is designed to provide source contributions to particular
events, such as the design concentrations determined from AERMOD, or user specified events.
The user may specify the "events" to process using the EVent pathway, which lists specific
combinations of receptor location, source group, and averaging period. By specifying the
EVENTFIL keyword, an input runstream file will be generated that can be used directly for
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EVENT processing. The events included in the generated EVENT processing input file are the
design concentrations defined by the RECTABLE keyword and the threshold violations identified
by the MAXIFILE keyword on the OU pathway.
3.2.10 The Model Re-start Capability
The AERMOD model has an optional capability to store intermediate results into an
unformatted file, so that the model run can be continued later in case of a power failure or a user
interrupt. This re-start option is controlled by the SAVEFILE and INITFILE keywords on the CO
pathway. The syntax and type of these keywords are summarized below:
Syntax:
CO SAVEFILE (Savfil) (Dayinc) (Savfil
CO INITFILE (Inifil)
Type:
Optional, Non-repeatable
The SAVEFILE keyword instructs the model to save the intermediate results to a file, and
controls the save options. All three parameters for this keyword are optional. If the user specifies
only the Savfil parameter, then the intermediate results are saved to the same file (and
overwritten) each time. If the user specifies both the Savfil and the Savfl2 parameters, then the
model alternates between the two files for storing intermediate results. The latter approach
requires additional disk space to handle two storage files. However, selecting two files avoids the
potential problem that the power failure or interrupt might occur while the temporary file is open
and the intermediate results are being copied to it. In such a case, the temporary results file
would be lost.
The optional Dayinc parameter allows the user to specify the number of days between
successive dumps. The default is to dump values at the end of each day, i.e., Dayinc = 1. For
larger modeling runs, where the SAVEFILE option is most useful, the additional execution time
required to implement this option is very small compared to the total runtime. To be most
effective, it is recommended that results be saved at least every 5 days.
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If no parameters are specified for the SAVEFILE keyword, then the model will store
intermediate results at the end of each day using a default filename of TMP.FIL.
The INITFILE keyword works in conjunction with the SAVEFILE keyword, and instructs
the model to initialize the results arrays from a previously saved file. The optional parameter,
Inifil, identifies the unformatted file of intermediate results to use for initializing the model. If no
Inifil parameter is specified, then the model assumes the default filename of TMP.FIL. If the file
doesn't exist or if there are any errors encountered in opening the file, then a fatal error message is
generated and processing is halted.
Note: It is important to note that if both the SAVEFILE and INITFILE keywords are used
in a the same model run, then different filenames must be specified for the Savfil and Inifil
parameters. Otherwise, the model will encounter an error in opening the files, and further
processing will be halted.
3.2.11 Post-1997 PM,» Processing
A new NAAQS for modeling PM10 was promulgated in July 1997. This guidance utilizes
the expected second high value of the 24-hour NAAQS replaced by a 3-year average of the 99th
percentile value of the frequency distribution and a 3-year average of the annual mean. Since the
Guideline on Air Quality Modeling precludes the use of a 3-year data set, a policy was
established that uses unbiased estimates of the 3-year averages, utilizing all meteorological data
(both single and multiple years of data) available. An unbiased estimate of the 99th percentile is
the fourth highest concentration, if one year of meteorological data are input to the model, or the
multi-year average of the fourth highest concentrations, if more than one year of meteorological
data are input to the model. Similarly, an unbiased estimate of the 3-year average annual mean is
simply the annual mean, if only one year of meteorological data are input to the model, or the
multi-year average annual mean if multiple years of meteorological data are used. Analogously
to the original NAAQS situation, the entire area is in compliance when the highest fourth high (or
highest average fourth high) and the highest annual mean (or the highest average annual mean)
are less than or equal to the NAAQS.
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AERMOD will process the 24-hour and annual averages for PM10 according to the new
NAAQS if the pollutant ID specified on the CO POLLUTE) card is PM10 or PM-10, and the CO
MULTYEAR card is not present. In this case, the model will compute an average of the fourth
highest concentrations at each receptor across the number of years of meteorological data being
processed. For a single year of data, the model will report the fourth highest concentration at
each receptor. For a five year period of data, the model will report the average of the five fourth-
highest values at each receptor. Also, for multiple year data files, the annual average will first be
calculated for each individual year of data, and the average of these across the number of years
will be calculated. This processing of the annual average across multiple years may give slightly
different results than the PERIOD average across the same time period, due to differences in the
number of calms from year to year. In order to accommodate this difference, the new PM10
NAAQS makes use of the ANNUAL average keyword for specifying the long-term average.
Users should be aware of the following restrictions which are applied to the new PM10
NAAQS processing.
1. The averaging periods are limited to the 24-hour and ANNUAL averages. Use of the
PERIOD average or a short-term average other than 24-hour will result in a fatal error
message being generated.
2. Only the FOURTH (or 4TH) highest value may be requested on the RECTABLE card for
24-hour averages. Specifying another high value on the RECTABLE card will result in a
fatal error message being generated.
3. The model will only process complete years of meteorological data, although there is no
restriction on the start date for the data. If less than one complete year of data is
processed, a fatal error message will be generated. If additional meteorological data
remains after the end of the last complete year of data, the remaining data will be ignored,
and a non-fatal warning message will be generated specifying the number of hours
ignored.
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4. The MULTYEAR card cannot be used with the new PM10NAAQS. Multiple year
analyses should be accomplished by including the multiple years of meteorology in a
single data file.
5. Since the 24-hour average design values for post-1997 PM10 analyses may consist of
averages over a multi-year period, they are incompatible with the EVENT processor. If
the MAXIFILE option is used to output 24-hour average threshold violations, these may
be used with the EVENT processor. Therefore, if the EVENTFIL option is used without
the MAXIFILE option for post-1997 PM10 analyses, a non-fatal warning message will be
generated, and the EVENTFIL option will be ignored.
3.2.12 Pre-1997 PM,n Processing
AERMOD may still be used to perform PM10 analyses according to the pre-1997 NAAQS.
This may be accomplished as before by use of the MULTYEAR card on the CO pathway, except
that the syntax for this keyword has been changed slightly. The syntax and type are now as
follows:
Syntax:
CO MULTYEAR H6H Savfil (Inifil)
Type:
Optional, Non-repeatable
where H6H is a new secondary keyword that identifies this as a pre-1997 analysis, the Savfil
parameter specifies the filename for saving the results arrays at the end of each year of
processing, and the Inifil parameter specifies the filename to use for initializing the results arrays
at the beginning of the current year. The Inifil parameter is optional, and should be left blank for
the first year in the multi-year series of runs. A non-fatal warning message will be generated if
the MULTYEAR card is used for pre-1997 NAAQS analyses.
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3.2.13 Debugging Output Option
The DEBUGOPT keyword on the CO pathway allows the user to request detailed files of
intermediate calculation results for debugging purposes. The syntax and type of the DEBUGOPT
keyword are summarized below:
Syntax:
CO DEBUGOPT MODEL (Dbgfil) and/or METEOR (Dbmfil)
Type:
Optional, Non-repeatable
where the MODEL and METEOR secondary keywords specify the type of debug information to
be provided, and the Dbgfil and Dbmfil parameters specify the names of the detailed message
files. This option allows for two types of debug output files. The MODEL secondary keyword
specifies that intermediate calculations related to the model results for each source and receptor,
e.g., dispersion parameters, plume heights, etc., are to be output. The METEOR secondary
keyword specifies that the gridded profiles of meteorological variables for each hour of data are
to be output. Use the DEBUGOPT keyword with CAUTION: it can produce very large files!
The METEOR profiles are printed to a separate file from the MODEL information. The
filenames for each type of output are optional, and if provided must immediately follow the
appropriate secondary keyword. The default filenames used if none are specified by the user are
MODEL.DBG and METEOR.DBG. The model will overwrite these files, without warning, if
they already exist.
3.2.14 Detailed Error Listing File
The ERRORFIL keyword on the CO pathway allows the user to request a detailed listing
file of all the messages generated by the model. This includes the error and warning messages
that are listed as part of the message summaries provided in the main output file, and also any
informational messages (such as occurrences of calm winds) and quality assurance messages that
are generated. The syntax and type of the ERRORFIL keyword are summarized below:
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Syntax:
CO ERRORFIL (Errfil)
Type:
Optional, Non-repeatable
where the Errfil parameter is the name of the detailed message file. If the optional Errfil
parameter is left blank, then the model will use a default filename of ERRORS.LST. A complete
description of the error and other types of messages generated by the model is provided in
Appendix C.
3.3 SOURCE PATHWAY INPUTS AND OPTIONS
The SOurce pathway contains the keywords that define the source information for a
particular model run. The model currently handles three source types, identified as point, volume
or area sources. The input parameters vary depending on the source type. For point sources, the
user can also identify building dimensions for nearby structure that cause aerodynamic downwash
influences on the source. The user can also identify groups of sources for which the model will
combine the results.
The LOCATION keyword, which identifies the source type and location, must be the first
card entered for each source. The only other requirement for order of the keywords is that the
SRCGROUP keyword must be the last keyword before the SO FINISHED card. The user may
group all of the LOCATION cards together, then group the source parameter cards together, or
they may want to group all input cards for a particular source together. All sources are given a
source ID by the user, which is used to link the source parameter inputs to the correct source or
sources. The source ID can be any alphanumeric string of up to eight characters.
As noted in Section 2.3, the number of sources is allocated dynamically at the time
AERMOD is run. This value, in concert with the other dynamically allocated arrays and input
requirements, is limited only by the amount of available memory.
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3.3.1 Identifying Source Types and Locations
The LOCATION keyword is used to identify the source type and the location of each
source to be modeled. The LOCATION card must be the first card entered for each source since
it identifies the source type, and dictates which parameters are needed and/or accepted. The
syntax, type and order of the LOCATION keyword are summarized below:
Syntax:
Type:
Mandatory, Repeatable
Must be first card for each source input
where the Srcid parameter is the alphanumeric source ID defined by the user (up to eight
characters), Srctyp is the source type, which is identified by one of the secondary keywords -
POINT. VOLUME. AREA. AREAPOLY. or AREACIRC - and Xs, Ys, and Zs are the x, y, and z
coordinates of the source location in meters. All three of the area source types use the same
numerical integration algorithm for estimating impacts from area sources, and are merely
different options for specifying the shape of the area source. The AREA source keyword may be
used to specify a rectangular-shaped area source with arbitrary orientation; the AREAPOLY
source keyword may be used to specify an area source as an irregularly-shaped polygon of up to
20 sides; and the AREACIRC source keyword may be used to specify a circular-shaped area
source (modeled as an equal-area polygon of 20 sides). Note that the source elevation, Zs, is an
optional parameter. If the default option to include elevated terrain effects is used and the source
elevation is omitted, a warning message will be generated and the source elevation will be given a
value of 0.0. The source elevation is not used by the model if the non-default FLAT terrain
option is used. While the default units of Zs are meters, the user may also specify source
elevations to be in feet by adding the SO ELEVUNIT FEET card immediately following the SO
STARTING card. The x (east-west) and y (north-south) coordinates are for the center of the
source for POINT. VOLUME, and AREACIRC sources, and are for one of the vertices of the
source for AREA and AREAPOLY sources. The source coordinates may be input as Universal
Transverse Mercator (UTM) coordinates, or may be referenced to a user-defined origin.
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Certain types of line sources can be handled in AERMOD using either a string of volume
sources, or as an elongated area source. The volume source algorithms are most applicable to line
sources with some initial plume depth, such as conveyor belts and rail lines. Section 1.2.2 of the
ISC Model User's Guide - Volume II (EPA, 1995) provides technical information on how to
model a line source with multiple volume sources. The use of the AERMOD area source
algorithm for elongated rectangles would be most applicable to near ground level line sources,
such as a viaduct.
The source ID entered on the LOCATION card identifies that source for the remainder of
the SO pathway inputs. Since the model accepts alphanumeric strings of up to eight characters
for the source ID, the sources can be identified with descriptive names, such as STACK 1,
STACK2, BOILERS, SLAGPILE, etc. This may also be useful if line sources are being modeled
as multiple volume or areas, as discussed above. Since they are part of the same physical source,
they can be given names that will identify them as being related, such as LINE1 A, LINE1B,
LINE1C, etc.
3.3.2 Specifying Source Release Parameters
The main source parameters are input on the SRCPARAM card, which is a mandatory
keyword for each source being modeled. Since the input parameters vary depending on the source
type, the different source types handled by the AERMOD model are discussed separately.
3.3.2.1 POINT Source Inputs.
The AERMOD POINT source algorithms are used to model releases from stacks and
isolated vents, as well as other kinds of sources. The syntax, type and order for the SRCPARAM
card for POINT sources are summarized below:
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Syntax:
SO SRCPARAM Srcid Ptemis Stkhgt Stktmp Stkvel Stkdia
Type:
Must follow the LOCATION card for each source input
where the Srcid parameter is the same source ID that was entered on the LOCATION card for a
particular source, and the other parameters are as follows:
Ptemis - point emission rate in g/s,
Stkhgt - release height above ground in meters,
Stktmp - stack gas exit temperature in degrees K,
Stkvel - stack gas exit velocity in m/s, and
Stkdia - stack inside diameter in meters.
An example of a valid SRCPARAM input card for a point source is given below:
where the source ID is STACK1, the emission rate is 16.71 g/s, the release height is 35.0 m, the
exit temperature is 444.0 K, the exit velocity is 22.7 m/s, and the inside stack diameter is 2.74 m.
All of the parameters must be present on the input card.
If a value of 0.0 is input for the exit temperature, AERMOD will adjust the exit
temperature for each hour to match the ambient temperature. This option allows the user to
model a plume that is released at ambient temperature. The user may also model a plume with an
exit temperature that exceeds the ambient temperature by a fixed amount by entering a negative
value for exit temperature equal in magnitude to the temperature difference. The model will add
the absolute value of a negative exit temperature to the ambient temperature for each hour to
obtain the exit temperature used in computing the buoyancy flux of the plume. The AERMOD
model does not include algorithms to model plumes that are released at temperatures below
ambient temperature. Such releases should be modeled with a dense gas model.
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Since the AERMOD model uses direction-specific building dimensions for all sources
subject to building downwash, there are no building parameters entered on the SRCPARAM card.
Building dimensions are entered on the BUILDHGT, BUILDWID, BUILDLEN, XBADJ, and
YBADJ cards described below in Section 3.3.3.
3.3.2.2 VOLUME Source Inputs.
The AERMOD VOLUME source algorithms are used to model releases from a variety of
industrial sources, such as building roof monitors, multiple vents, and conveyor belts. The
syntax, type and order for the SRCPARAM card for VOLUME sources are summarized below:
Syntax:
SO SRCPARAM Srcid Vlemis Relhgt Syinit Szinit
Type:
Q j Must follow the LOCATION card for each source input
where the Srcid parameter is the same source ID that was entered on the LOCATION card for a
particular source, and the other parameters are as follows:
Vlemis - volume emission rate in g/s,
Relhgt - release height (center of volume) above ground, in meters,
Syinit - initial lateral dimension of the volume in meters, and
Szinit - initial vertical dimension of the volume in meters.
The following table, which is explained in more detail in Section 1.2.2 of the ISC Model User's
Guide - Volume II, summarizes the suggested procedures to be used for estimating the initial
lateral and vertical dimensions for various types of volume and line sources.
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TABLE 3-1.
SUMMARY OF SUGGESTED PROCEDURES FOR ESTIMATING
INITIAL LATERAL DIMENSIONS oyo AND
INITIAL VERTICAL DIMENSIONS om FOR VOLUME AND LINE SOURCES
Type of Source
Procedure for Obtaining
Initial Dimension
(a) Initial Lateral Dimensions (a )
Single Volume Source
a = length of side divided by 4.3
Line Source Represented by Adjacent Volume oyo = length of side divided by 2.15
Sources (see Figure l-8(a) in EPA, 1995)
Line Source Represented by Separated Volume oyo = center to center distance divided by
Sources (see Figure l-8(b) in EPA, 1995) 2.15
(b) Initial Vertical Dimensions (ozo)
Surface-Based Source (he ~ 0)
vertical dimension of source divided
by 2.15
Elevated Source (he > 0) on or Adjacent to a ozo = building height divided by 2.15
Building
Elevated Source (he > 0) not on or Adjacent to ozo = vertical dimension of source divided
a Building by 4.3
3.3.2.3 AREA Source Inputs
The AERMOD area source algorithm is used to model low level or ground level releases
with no plume rise (e.g., storage piles, slag dumps, and lagoons). The AERMOD model uses a
numerical integration approach for modeling impacts from area sources. When the TOXICS
option is specified, the area source integration routine is optimized to reduce model runtime. This
is accomplished by incorporation of a three-tiered approach using the Romberg numerical
integration, a 2-point Gaussian Quadrature routine for numerical integration, or a point source
approximation based on the location of the receptor relative to the source. In the regulatory
default mode the Romberg numerical integration is utilized for all receptors.
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The AERMOD model includes three options for specifying the shape of an area source:
the AREA source type may be used to specify rectangular areas that may also have a rotation
angle specified relative to a north-south orientation; the ARE APPLY source type may be used to
specify an area source as an irregularly-shaped polygon of up to 20 sides; and the AREACIRC
source keyword may be used to specify a circular-shaped area source (modeled as an equal-area
polygon of 20 sides). The source parameter inputs for each of the area source types is described
below.
AREA Source Type
The rotation angle for rectangular AREA sources is specified relative to the vertex used to
define the source location on the SO LOCATION card (e.g., the southwest corner). The syntax,
type and order for the SRCPARAM card for AREA sources are summarized below:
Syntax:
Type:
OvH • Must follow the LOCATION card for each source input
where the Srcid parameter is the same source ID that was entered on the LOCATION card for a
particular source, and the other parameters are as follows:
Aremis -
Relhgt -
Xinit -
Yinit -
Angle -
Szinit -
area emission rate in g/(s-m2),
release height above ground in meters,
length of X side of the area (in the east-west direction if Angle is 0 degrees)
in meters,
length of Y side of the area (in the north-south direction if Angle is 0
degrees) in meters (optional),
orientation angle for the rectangular area in degrees from North, measured
positive in the clockwise direction (optional), and
initial vertical dimension of the area source plume in meters (optional).
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It should be noted that the emission rate for the area source is an emission rate per unit area,
which is different from the point and volume source emission rates, which are total emissions for
the source.
If the optional Yinit parameter is omitted, then the model assumes that the area is a square,
i.e., Yinit = Xinit. If the optional Angle parameter is omitted, then the model assumes that the
area is oriented in the north-south and east-west directions, i.e., Angle = 0.0. If the Angle
parameter is input, and the value does not equal 0.0, then the model will rotate the area clockwise
around the vertex defined on the SO LOCATION card for this source. Figure 3-1 illustrates the
relationship between the Xinit, Yinit, and Angle parameters and the source location, (Xs,Ys), for
a rotated rectangle. The Xinit dimension is measured from the side of the area that is
counterclockwise along the perimeter from the vertex defined by (Xs,Ys), while the Yinit
dimension is measured from the side of the area that is clockwise from (Xs,Ys). The Angle
parameter is measured as the orientation relative to North of the side that is clockwise from
(Xs,Ys), i.e. the side with length Yinit. The Angle parameter may be positive (for clockwise
rotation) or negative (for counterclockwise rotation), and a warning message is generated if the
absolute value of Angle is greater than 180 degrees. The selection of the vertex to use for the
source location is not critical, as long as the relationship described above for the Xinit, Yinit, and
Angle parameters is maintained.
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FIGURE 3-1. RELATIONSHIP OF AREA SOURCE PARAMETERS FOR ROTATED
RECTANGLE
5-23
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By making the Yinit and Angle parameters optional, the area source input data for the
previous versions of the ISC2 model can be used with the AERMOD model. The aspect ratio
(i.e., length/width) for area sources should generally be less than about 10 to 1. If this is
exceeded, then the model will generate a non-fatal warning message, and the user should consider
subdividing the area to achieve a 10 to 1 aspect ratio (or less) for all subareas.
The optional Szinit parameter may be used to specify an initial vertical dimension to the
area source plume, similar to the use of the Szinit parameter for volume sources. This parameter
may be important when the area source algorithm is used to model mechanically generated
emission sources, such as mobile sources. In these cases, the emissions may be turbulently mixed
near the source by the process that is generating the emissions, and therefore occupy some initial
depth. For more passive area source emissions, such as evaporation or wind erosion, the Szinit
parameter may be omitted, which is equivalent to using an initial sigma-z of zero.
An example of a valid SRCPARAM input card for a rectangular area source is given
below:
where the source ID is SLAGPILE, the emission rate is 0.0015 g/(s-m2), the release height is 5.0
m, the X-dimension is 50.0 m, the Y-dimension is 100.0 m, and the orientation angle is 30.0
degrees clockwise from North.
Since the numerical integration algorithm can handle elongated areas with aspect ratios of
up to 10 to 1, the AERMOD area source algorithm may be useful for modeling certain types of
line sources. There are no restrictions on the placement of receptors relative to area sources for
the AERMOD model. Receptors may be placed within the area and at the edge of an area. The
AERMOD model will integrate over the portion of the area that is upwind of the receptor.
However, since the numerical integration is not performed for portions of the area that are closer
than 1.0 meter upwind of the receptor, caution should be used when placing receptors within or
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adjacent to areas that are less than a few meters wide. More technical information about the
application of the AERMOD area source algorithm is provided in Sections 1.2.3 and 2.2.3 of the
ISC Model User's Guide - Volume II (EPA, 1995).
AREAPOLY Source Type
The AREAPOLY source type may be used to specify an area source as an arbitrarily-
shaped polygon of between 3 and 20 sides (the number of sides allowed may be increased by
modifying the NVMAX parameter in MODULE MAIN1). This source type option provides the
user with considerable flexibility for specifying the shape of an area source. The syntax, type and
order for the SRCPARAM card for AREAPOLY sources are summarized below:
Syntax:
Type:
Mandatory, Repeatable
Order* Must follow the LOCATION card for each source input
where the Srcid parameter is the same source ID that was entered on the LOCATION card for a
particular source, and the other parameters are as follows:
Aremis - area emission rate in g/(s-m2),
Relhgt - release height above ground in meters,
Nverts - number of vertices (or sides) of the area source polygon,
Szinit - initial vertical dimension of the area source plume in meters (optional).
As with AREA sources, the emission rate for the source is an emission rate per unit area, which is
different from the point and volume source emission rates, which are total emissions for the
source. The number of vertices (or sides) used to define the area source polygon may vary
between 3 and 20. The locations of the vertices are specified by use of the AREA VERT
keyword, which applies only to AREAPOLY sources. The syntax, type and order for the
AREA VERT keyword used for AREAPOLY sources are summarized below:
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Syntax:
Type:
Mandatory for AREAPOLY sources, Repeatable
Order:
Must follow the LOCATION card for each source input
where the Xv(i) and Yv(i) are the x-coordinate and y-coordinate values of the vertices of the area
source polygon. There must by Nverts pairs of coordinates for the area source, where Nverts in
the number of vertices specified for that source on the SRCPARAM card. The first vertex, Xv(l)
and Yv(l), must also match the coordinates given for the source location on the LOCATION
card, Xs and Ys. The remaining vertices may be defined in either a clockwise or counter-
clockwise order from the point used for defining the source location.
Since the numerical integration algorithm can handle elongated areas with aspect ratios of
up to 10 to 1, the AERMOD area source algorithm may be useful for modeling certain types of
line sources. There are no restrictions on the placement of receptors relative to area sources for
the AERMOD model. Receptors may be placed within the area and at the edge of an area. The
AERMOD model will integrate over the portion of the area that is upwind of the receptor.
However, since the numerical integration is not performed for portions of the area that are closer
than 1.0 meter upwind of the receptor, caution should be used when placing receptors within or
adjacent to areas that are less than a few meters wide.
AREACIRC Source Type
The AREACIRC source type may be used to specify an area source as a circular shape.
The model will automatically generate a regular polygon of up to 20 sides to approximate the
circular area source. The polygon will have the same area as that specified for the circle. The
syntax, type and order for the SRCPARAM card for AREACIRC sources are summarized below:
Syntax:
Type:
Order:
Must follow the LOCATION card for each source input
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where the Srcid parameter is the same source ID that was entered on the LOCATION card for a
particular source, and the other parameters are as follows:
Aremis -
Relhgt -
Radius -
Nverts -
area emission rate in g/(s-m2),
release height above ground in meters,
radius of the circular area in meters,
number of vertices (or sides) of the area source polygon (optional, 20 sides
will be used if omitted),
Szinit - initial vertical dimension of the area source plume in meters (optional).
As with AREA sources, the emission rate for the source is an emission rate per unit area, which is
different from the point and volume source emission rates, which are total emissions for the
source.
3.3.3 Specifying Building Downwash Information
As noted above, the AERMOD model include algorithms to model the effects of buildings
downwash on emissions from nearby or adjacent point sources. The building downwash
algorithms do not apply to volume or area sources. For a technical description of the building
downwash algorithms in AERMOD, the user is referred to Schulman, et. al. (2000). The
AERMOD model uses direction-specific information for all building downwash cases.
There are five keywords that are used to specify building downwash information:
BUILDHGT, BUILDWID, BUILDLEN, XBADJ, YBADJ. The syntax, type and order for the
BUILDHGT keyword, used to input direction specific building heights, are summarized below:
Syntax:
SO BUILDHGT Srcid (or Srcrng) Dsbh(i),i=l,36 (16 for LT)
Type:
Optional, Repeatable
Order:
Must follow the LOCATION card for each source input
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where the Srcid parameter is the same source ID that was entered on the LOCATION card for a
particular source. The user also has the option of specifying a range of sources (the Srcrng
parameter) for which the building heights apply, instead of identifying a single source. This is
accomplished by two source ID character strings separated by a dash, e.g., STACK1-STACK10.
Since the model reads the source range as a single input field there must not be any spaces
between the source IDs. The model then places the building heights that follow (the Dsbh(i)
parameter) into the appropriate arrays for all Srcid's that fall within that range, including
STACK1 and STACK10.
When comparing a source ID to the range limits for a Srcrng parameter, the model
separates the source IDs into three parts: an initial alphabetical part, a numerical part, and then the
remainder of the string. Each part is then compared to the corresponding parts of the source
range, and all three parts must satisfy the respective ranges in order for the source ID to be
included. If there is no numeric part, then the ID consists of only one alphabetical part. If the ID
begins with a numeric character, then the initial alphabetical part defaults to a single blank. If
there is no trailing alphabetical part, then the third part also defaults to a single blank part. If the
trailing part consists of more than one alphabetical or numeric field, it is all lumped into one
character field. For example, the source ID 'STACK2' consists of the parts 'STACK' plus '2' plus
a single trailing blank,''. By comparing the separate parts of the source IDs, it can be seen that
STACK2 falls between the range 'STACK1-STACK10.' For a three-part example, it can also be
seen that VENT1B falls within the range of VENT1A-VENT1C. However, VENT2 does not fall
within the range of VENT1A to VENT3B, since the third part of VENT2 is a single blank, which
does not fall within the range of A to C. This is because a blank character will precede a normal
alphabetical character. Normally, the source ranges will work as one would intuitively expect for
simple source names. Most importantly, for names that are made up entirely of numeric
characters, the source ranges will be based simply on the relative numerical values. The user is
strongly encouraged to check the summary of model inputs to ensure that the source ranges were
interpreted as expected, and also to avoid using complex source names in ranges, such as
AA1B2C-AB3A3C. Since the order of keywords within the SO pathway is quite flexible, it is
also important to note that the building heights will only be applied to those sources that have
been defined previously in the input file.
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Following the Srcid or the Srcrng parameter, the user inputs 36 direction-specific building
heights (Dsbh parameter) in meters, beginning with the 10 degree flow vector (wind blowing
toward 10 degrees from north), and incrementing by 10 degrees in a clockwise direction. Some
examples of building height inputs are presented below:
SO BUILDHGT STACK1 34. 34. 34. 34. 34. 34. 34. 34. 34. 34. 34. 34.
SO BUILDHGT STACK1 34. 34. 34. 34. 34. 34. 34. 34. 34. 34. 34. 34.
SO BUILDHGT STACK1 34. 34. 34. 34. 34. 34. 34. 34. 34. 34. 34. 34.
The first example illustrates the use of repeat cards if more than one card is needed to input all of
the values. The values are processed in the order in which they appear in the input file, and are
identified as being repeat cards by repeating the Srcid parameter. The first and second examples
produce identical results within the model. The second one illustrates the use of a repeat value
that can simplify numerical input in some cases. The field "36*34.0" is interpreted by the model
as "repeat the value 34.0 a total of 36 times." This is also used in the third example where the
building height is constant for directions of 10 degrees through 330 degrees, and then is set to 0.0
(e.g. the stack may be outside the region of downwash influence) for directions 340 through 360.
The third example also uses a source range rather than a single source ID. The last example
illustrates building heights which vary by direction, and shows that the number of values on each
card need not be the same. For improved readability of the input file, the user may want to put
the numerical inputs into "columns," but there are no special rules regarding the spacing of the
parameters on this keyword.
The BUTLDWTD keyword is used to input direction-specific building widths for
downwash analyses. The syntax for this keyword, which is very similar to the BUILDHGT
keyword, is summarized below, along with the type and order information:
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Syntax:
SO BUILDWID Srcid (or Srcrng) Dsbw(i),i=l,36 (16 for LT)
Type:
Optional, Repeatable
Order:
Must follow the LOCATION card for each source input
For a description of the Srcid and Srcrng parameters, and for a discussion and examples of the
numeric input options, refer to the BUILDHGT keyword above. The Dsbw(i) parameter contains
the 36 direction-specific building widths. The directions proceed in a clockwise direction,
beginning with the 10 degree flow vector.
The BUILDLEN keyword is used to input direction-specific along-flow building lengths
for downwash analyses. Figure 3-2 shows the relationship of the projected building to this
dimension. The syntax for this keyword, which is very similar to the BUILDHGT keyword, is
summarized below, along with the type and order information:
Syntax:
Type:
Order:
Must follow the LOCATION card for each source input
For a description of the Srcid and Srcrng parameters, and for a discussion and examples of the
numeric input options, refer to the BUILDHGT keyword above. The Dsbl(i) parameter contains
the 36 direction-specific building lengths. The directions proceed in a clockwise direction,
beginning with the 10 degree flow vector.
-------
Figure 3-2 shows the relationship of the projected building to these distances.
0-
Q-UD-QOUUO
FIGURE 3-2. SCHEMATIC DIAGRAM IDENTIFYING NEW BUILDING DATA FOR
PRIME DOWNWASH
The XBADJ and YBADJ keywords are used to input direction-specific along-flow and
across-flow distances from the stack to the center of the upwind face of the projected building,
respectively. Figure 3-2 shows the relationship of the projected building to these distances. The
syntax for these keywords, which is very similar to the BUILDHGT keyword, are summarized
below, along with the type and order information:
-------
Syntax:
Type:
Order:
SO XBADJ
Optional,
Must foil
Srcid (or Srcrng) Xbadj ( i) , i=l, 3 6
Repeatable
ow the LOCATION card for each source
input
Syntax:
Type:
Order:
SO YBADJ
Optional,
Must foil
Srcid (or Srcrng) Ybadj ( i) , i=l, 3 6
Repeatable
ow the LOCATION card for each source
input
For a description of the Srcid and Srcrng parameters, refer to the BUILDHGT keyword above.
The Xbadj(i) parameter contains the 36 direction-specific along-flow distances from the stack to
the center of the upwind face and the Ybadj (i) parameter contains the 36 direction-specific
across-flow distances from the stack to the center of the upwind face. The directions proceed in a
clockwise direction, beginning with the 10 degree flow vector.
3.3.4 Specifying Urban Sources
As discussed in Section 3.2.4, the AERMOD model allows the user to incorporate the
effects of increased surface heating from an urban area on pollutant dispersion under stable
atmospheric conditions. The user specifies the parameters for the urban area on the CO
URBANOPT card (see Section 3.2.4), and identifies which sources are to be modeled with urban
effects using the SO URBANSRC card. If a source is not included on the URB ANSRC card, it
will be modeled without the urban effects. The syntax, type and order for the URBANSRC
keyword are summarized below:
Syntax:
Type:
Order:
Optional, Repeatable
Must follow the LOCATION card for each source input
where the Srcid's and Srcrng's are the individual source IDs and/or source ranges that are to be
modeled with urban effects. Source ranges, which are described in more detail in the description
of the BUILDHGT keyword (Section 3.3.3), are input as two source IDs separated by a dash, e.g.,
-------
STACK1-STACK10. Individual source IDs and source ranges may be used on the same card. If
more than one input card is needed to define the urban sources, then additional cards may be
input.
3.3.5 Using Variable Emission Rates
The AERMOD model provide the option of specifying variable emission rate factors for
individual sources or for groups of sources. The factors may vary on different time scales, such
as by season, hour-of-day, etc. The EMISFACT keyword provides the user the option of
specifying variable emission rate factors for sources modeled by the AERMOD model. The
syntax, type and order of this keyword are summarized below:
Syntax:
Type:
Optional, Repeatable
Order:
Must follow the LOCATION card for each source input
where the Srcid parameter is the same source ID that was entered on the LOCATION card for a
particular source. The user also has the option of using the Srcrng parameter for specifying a
range of sources for which the emission rate factors apply, instead of identifying a single source.
This is accomplished by two source ID character strings separated by a dash, e.g.,
STACK1-STACK10. The use of the Srcrng parameter is explained in more detail in Section
3.3.3 above for the BUILDHGT keyword.
The parameter Qflag is the variable emission rate flag, and is one of the following
secondary keywords:
SEASON - emission rates vary seasonally (n=4),
MONTH - emission rates vary monthly (n=12),
HROFDY - emission rates vary by hour-of-day (n=24),
WSPEED - emission rates vary by wind speed (n=6),
-------
SEASHR- emission rates vary by season and hour-of-day (n=96),
SHRDOW - emission rates vary by season, hour-of-day, and day-of-week [M-F, Sat.,
Sun.] (n=288), and
SHRDOW7 - emission rates vary by season, hour-of-day, and the seven days of the
week [M,Tu,W,Th,F,Sat.,Sun.] (n=672).
The Qfact array is the array of factors, where the number of factors is shown above for each Qflag
option. The seasons are defined in the following order: Winter (Dec., Jan., Feb.), Spring (Mar.,
Apr., May), Summer (Jun., Jul., Aug.), and Fall (Sep., Oct., Nov.). The wind speed categories
used with the WSPEED option may be defined using the ME WINDCATS keyword. If the
WINDCATS keyword is not used, the default wind speed categories are defined by the upper
bound of the first five categories as follows (the sixth category is assumed to have no upper
bound): 1.54, 3.09, 5.14, 8.23, and 10.8 m/s. The EMISFACT card may be repeated as many
times as necessary to input all of the factors, and repeat values may be used for the numerical
inputs. An example of each of these options is presented below, with column headers to indicate
the order in which values are to be to input:
-------
** WINTER SPRING SUMMER FALL
SO EMISFACT STACK1 SEASON 0.50 0.50 1.00 0.75
** JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
SO EMISFACT STACK1 MONTH 0.1 0.2 0.3 0.4 0.5 0.5 0.5 0.6 0.7 1.0 1.0 1.0
SO EMISFACT STACK1 HROFDY
** or, equivalently: 1-5 6 7-17 18 19-24
SO EMISFACT STACK1 HROFDY 5*0.0 0.5 11*1.0 0.5 6*0.0
SO EMISFACT STACK1 SEASHR enter 24 hourly scalars for each of the four
seasons (winter, spring, summer, fall), e.g.,
SO EMISFACT STACK1 SEASHR
Winter
24*0.50
Spring
24*0.50
Fall
24*0.75
SO EMISFACT STACK1 SHRDOW enter 24 hourly scalars for each of the four
seasons (winter, spring, summer, fall), first
for Weekdays (Monday-Friday), then for Saturdays,
and finally for Sundays, e.g.,
** Weekdays:
SO EMISFACT STACK1 SHRDOW
** Saturdays:
SO EMISFACT STACK1 SHRDOW
** Sundays:
SO EMISFACT STACK1 SHRDOW
SO EMISFACT STACK1 SHRDOW7 enter 24 hourly scalars for each of the four
seasons (winter, spring, summer, fall), first
for Mondays, then for Tuesdays, ..., then for Saturdays
and finally for Sundays, e.g.,
** Mondays: Winter
SO EMISFACT STACK1 SHRDOW7 24*1.0
** Tuesdays: Winter
Spring
Summer Fall
24*0.6 24*0.8
Summer Fall
** Saturdays:
SO EMISFACT STACK1 SHRDOW7 24*0.5 24*0.4 24*0.3 24*0.4
** Sundays:
SO EMISFACT STACK1 SHRDOW7 24*0.25 24*0.2 24*0.15 24*0.2
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3.3.6 Adjusting the Emission Rate Units for Output
The default emission rate units for the AERMOD model are grams per second for point
and volume sources, and grams per second per square meter for area sources. By default, the
model converts these input units to output units of micrograms per cubic meter for concentration
calculations. This is accomplished by applying a default emission rate unit factor of 1.0E06 for
concentration.
The EMISUNIT keyword on the SO pathway allows the user to specify a different unit
conversion factor, and to specify the appropriate label for the output units for either concentration
calculations. The syntax and type of the EMISUNIT keyword are summarized below:
Syntax:
SO EMISUNIT Emifac Emilbl Conlbl
Type:
Optional, Non-repeatable
where the parameter Emifac is the emission rate unit factor, Emilbl is the label for the emission
units (up to 40 characters), and Conlbl is the output unit label (up to 40 characters) for
concentration calculations. For example, to produce output concentrations in milligrams per
cubic meter, assuming input units of grams per sec, the following card could be input:
SO EMISUNIT 1.0E3 GRAMS/SEC MI L LI GRAMS/M** 3
since there are 1.0E3 milligrams per gram. The emission rate unit factor applies to all sources for
a given run. Since the model uses one or more spaces to separate different fields on the input
runstream images, it is important that there not be any spaces within the label fields on this card.
Thus, instead of entering 'GRAMS PER SECOND' for the emission label, a label of
'GRAMS/SECOND', or 'GRAMS-PER-SECOND' or an equivalent variation should be used.
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3.3.7 Specifying Variables for Settling. Removal and Deposition Calculations
The current version of the AERMOD model does not include algorithms to handle the
gravitational settling and removal by dry deposition of particulates.
3.3.8 Specifying Variables for Precipitation Scavenging and Wet Deposition Calculations
The current version of the AERMOD model does not include algorithms to handle the
scavenging and removal by wet deposition (i.e., precipitation scavenging) of gases and
particulates.
3.3.9 Specifying an Hourly Emission Rate File
The source (SO) pathway includes an option for inputting hourly emission rates for the
AERMOD model, controlled by the HOUREMIS keyword. AERMOD currently allows for a
single hourly emission file to be used with each model run. The syntax, type and order for this
keyword are summarized below:
Syntax:
SO HOUREMIS Emifil Srcid's (and/or Srcrng's)
Type:
Optional, Repeatable
Must follow the LOCATION card for each source input
where the Emifil parameter specifies the filename (up to 40 characters) for the hourly emission
file, and Srcid or Srcrng identify the source or sources for which hourly emission rates are
included. Source ranges, which are described in more detail in the description of the BUILDHGT
keyword (Section 3.3.3), are input as two source IDs separated by a dash, e.g.,
STACK1-STACK10. The user may include more than one HOUREMIS card in a runstream file,
if needed to specify additional sources, but there can be only one hourly emissions file, and
therefore the filename must be the same on all HOUREMIS cards.
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The format of each record of the hourly emissions file includes a pathway and keyword
(SO HOUREMIS), followed by the Year, Month, Day, Hour, Source ID, and emission rate (in the
appropriate units). For point sources, the stack gas exit temperature (K), and stack gas exit
velocity (m/s) are also specified. The hourly emissions file is processed using the same routines
used to process the runstream input file, therefore each of the parameters must be separated by at
least one space, but otherwise the format is flexible. It is also not necessary to include the SO
HOUREMIS on each line, as long as the parameters (Year, Month, etc.) do not begin before
column 13.
The data in the hourly emission file must include the exact same dates as are included in
the meteorological input files, and the source IDs must correspond to the source IDs defined on
the SO LOCATION cards and be in the same order. Multiple records are required to define the
emissions for one hour if more than one source is referenced. The model will check for a date
mismatch between the hourly emissions file and the meteorological data, and also for a source ID
mismatch. However, it is not necessary to process the entire hourly emissions file on each model
run, i.e., the correct emissions data will be read if the ME DAYRANGE or the ME STARTEND
cards (see Section 3.5.4) are used, as long as all the dates (including those that are processed and
those that are skipped) match the meteorological data files. An example of several lines from an
hourly emissions file for two point sources is provided below:
SO HOUREMIS
SO HOUREMIS
SO HOUREMIS
SO HOUREMIS
SO HOUREMIS
SO HOUREMIS
SO HOUREMIS
SO HOUREMIS
44
The model will use the stack release height and stack inside diameter defined on the SO
SRCPARAM card, but will use the emission rate, exit temperature and exit velocity from the
hourly emission file. If the emission rate, exit temperature and exit velocity are not included for a
particular hour, i.e, any or all of those fields are blank, the model will interpret emissions data for
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that hour as missing and will set the parameters to zero. Since the emission rate will be zero,
there will be no calculations made for that hour and that source.
3.3.10 Including Source Data From an External File
The user has the option of including source data from an external file by using the
INCLUDED keyword on the source (SO) pathway. An SO INCLUDED card may be placed
anywhere within the source pathway, after the STARTING card and before the FINISHED card
(i.e., the SO STARTING and SO FINISHED cards cannot be included in the external file). The
data in the included file will be processed as though it were part of the runstream file. The syntax
and type of the INCLUDED keyword are summarized below:
Syntax:
Type:
SO INCLUDED Incfil
Optional, Repeatable
where the Incfil parameter is a character field of up to 40 characters that identifies the filename
for the included file. The contents of the included file must be valid runstream images for the
source pathway. If an error is generated during processing of the included file, the error message
will report the line number of the included file (see Appendix C). If more than one INCLUDED
file is specified for the source pathway, the user will first need to determine which file the error
occurred in. If the starting column of the main runstream input file is shifted from column 1 (see
Section 2.4.8), then the runstream images in the included file must be offset by the same amount.
3.3.11 Using Source Groups
The AERMOD model allows the user to group contributions from particular sources
together. Several source groups may be setup in a single run, and they may, for example, be used
to model impacts from the source being permitted, the group of increment consuming PSD
sources, and the group of all sources for comparison to a NAAQS in a single run. There is always
at least one source group in a run, which may consist of all sources, so the SRCGROUP keyword
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has been made mandatory in the AERMOD model. The syntax, type and order of the
SRCGROUP keyword are summarized below:
Syntax:
Type:
Order* Must be the last keyword in the SO pathway before FINISHED
where the Grpid parameter is an alphanumeric string of up to eight characters that identifies the
group name. The Srcid's and Srcrng's are the individual source IDs and/or source ranges that
make up the group of sources. Source ranges, which are described in more detail in the
description of the BUILDHGT keyword (Section 3.3.3), are input as two source IDs separated by
a dash, e.g., STACK1-STACK10. Individual source IDs and source ranges may be used on the
same card. If more than one input card is needed to define the sources for a particular group, then
additional cards may be input, repeating the pathway, keyword and group ID.
A special group ID has been reserved for use in specifying the group of all sources. When
Grpid = ALL, the model will automatically setup a source group called ALL that includes all
sources modeled for that particular run. If desired, the user can setup a group of all sources with a
different group ID by explicitly specifying all sources on the input card(s).
As noted in Section 2.3, the number of source groups is allocated dynamically at the time
AERMOD is run. This value, in concert with the other dynamically allocated arrays and input
requirements, is limited only by the amount of available memory.
As discussed in Sections 1.2.4.6 and 3.2.9, it is sometimes important for a user to know
the contribution of a particular source to the total result for a group. These source contribution
analyses are facilitated for short term averages by the use the EVENT processing capabilities in
the AERMOD model. EVENT processing uses the same source groups that are identified by
AERMOD (when the input file is generated using the CO EVENTFIL option), but the model is
structured in a way that it retains individual source results for particular events. Refer to the
sections noted above for a more complete description of EVENT processing and its uses.
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3.4 RECEPTOR PATHWAY INPUTS AND OPTIONS
The REceptor pathway contains keywords that define the receptor information for a
particular model run. The RE pathway contains keywords that allow the user to define Cartesian
grid receptor networks and/or polar grid receptor networks, with either uniform or non-uniform
grid spacing, as well as discrete receptor locations referenced to a Cartesian or a polar system. As
noted in Section 2.3, the number of receptors and receptor networks are allocated dynamically at
the time AERMOD is run. This value, in combination with the other dynamically allocated
arrays and input requirements, is limited only by the amount of available memory.
All of the receptor options in AERMOD allow the user to input terrain elevations and hill
height scales for each receptor, both of which are needed when applying AERMOD in an elevated
terrain situation. To facilitate the generation of hill height scales for AERMOD, a terrain
preprocessor, called AERMAP, has been developed (EPA, 2004c). The AERMAP terrain
preprocessor, which uses U.S. Geological Survey (USGS) Digital Elevation Model (DEM) data
as an input, may also be used to generate the terrain elevations for the receptor locations. The
AERMAP program generates an output file that contains the receptor pathway data for AERMOD
in the format described below. This file may either be cut and pasted into the AERMOD
runstream file, or may be included as an external file using the RE INCLUDED card (see Section
3.4.4).
The default units for receptor elevations for the AERMOD model are in meters, however,
the user may specify receptor elevations to be in units of feet by adding the RE ELEVUNIT
FEET card immediately after the RE STARTING card. Since the AERMAP terrain preprocessor
outputs elevations in meters and includes the RE ELEVUNIT METERS card as the first record,
the AERMAP data must be placed at the beginning of the receptor pathway.
3.4.1 Defining Networks of Gridded Receptors
Two types of receptor networks are allowed by the AERMOD model. A Cartesian grid
network, defined through the GRIDCART keyword, includes an array of points identified by their
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x (east-west) and y (north-south) coordinates. A polar network, defined by the GRIDPOLR
keyword, is an array of points identified by direction and distance from a user-defined origin.
Each of these keywords has a series of secondary keywords associated with it that are used to
define the network, including any receptor elevations for elevated terrain and flagpole receptor
heights. The GRIDCART and GRIDPOLR keywords can be thought of as "sub-pathways," since
their secondary keywords include a STArt and an END card to define the start and end of inputs
for a particular network.
3.4.1.1 Cartesian Grid Receptor Networks.
Cartesian grid receptor networks are defined by use of the GRIDCART keyword. The
GRIDCART keyword may be thought of as a "sub-pathway," in that there are a series of
secondary keywords that are used to define the start and the end of the inputs for a particular
network, and to select the options for defining the receptor locations that make up the network.
The syntax and type of the GRIDCART keyword are summarized below:
Syntax:
RE GRIDCART Netid STA
XYINC Xinit Xnum Xdelta Yinit Ynum Ydelta
or XPNTS Gridxl Gridx2 Gridx3 .... Gridxn, and
YPNTS Gridyl Gridy2 Gridy3 .... Gridyn
ELEV Row Zelevl Zelev2 Zelev3 ... Zelevn
HILL Row Zhilll Zhill2 Zhill3 ... Zhilln
FLAG Row Zflagl Zflag2 Zflag3 ... Zflagn
END
Type:
Optional, Repeatable
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where the parameters are defined as follows:
Netid
STA
XYINC
Xinit
Xnum
Xdelta
Yinit
Ynum
Ydelta
XPNTS
Gridxl
Gridxn
YPNTS
Gridyl
Gridyn
ELEV
Row
Zelev
HILL
Row
Zelev
FLAG
Row
Zflag
END
Receptor network identification code (up to eight alphanumeric
characters )
Indicates the STArt of GRIDCART inputs for a particular network,
repeated for each new Netid
Keyword identifying uniform grid network generated from x and y
increments
Starting x-axis grid location in meters
Number of x-axis receptors
Spacing in meters between x-axis receptors
Starting y-axis grid location in meters
Number of y-axis receptors
Spacing in meters between y-axis receptors
Keyword identifying grid network defined by a series
of discrete x and y coordinates (used with YPNTS)
Value of first x-coordinate for Cartesian grid (m)
Value of 'nth' x-coordinate for Cartesian grid (m)
Keyword identifying grid network defined by a series
of discrete x and y coordinates (used with XPNTS)
Value of first y-coordinate for Cartesian grid (m)
Value of 'nth' y-coordinate for Cartesian grid (m)
Keyword to specify that receptor elevations follow (optional)
Indicates which row (y-coordinate fixed) is being
input (Row=l means first, i.e., southmost row)
An array of receptor terrain elevations (m) for a
particular Row (default units of meters may be changed to feet by
use of RE ELEVUNIT keyword) , number of entries per
row equals the number of x-coordinates for that network
Keyword to specify that hill height scales follow (optional)
Indicates which row (y-coordinate fixed) is being
input (Row=l means first, i.e., southmost row)
An array of hill height scales (m) for a
particular Row (default units of meters may be changed to feet by
use of RE ELEVUNIT keyword) , number of entries per
row equals the number of x-coordinates for that network
Keyword to specify that flagpole receptor heights
follow (optional)
Indicates which row (y-coordinate fixed) is being
input (Row=l means first, i.e., southmost row)
An array of receptor heights (m) above local terrain
elevation for a particular Row (flagpole receptors), number of
entries per row equals the number of x-coordinates for that
network
Indicates the END of GRIDCART inputs for a particular network,
repeated for each new Netid
The ELEV. HILL, and FLAG keywords are optional inputs, and are only needed if
elevated terrain or flagpole receptor heights are to be used. If elevated terrain is being used, then
both the ELEV and HILL inputs are needed for each receptor. If the ELEV and HILL keywords
are used and the model is being run with the flat terrain option (see Section 3.2.2), then the
elevated terrain height inputs will be ignored by the model, and a non-fatal warning message will
be generated. If the elevated terrain option is selected, and no elevated terrain heights are entered,
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the elevations will default to 0.0 meters, and warning messages will also be generated. The
model handles flagpole receptor height inputs in a similar manner.
The order of cards within the GRIDCART subpathway is not important, as long as all
inputs for a particular network are contiguous and start with the STA secondary keyword and end
with the END secondary keyword. It is not even required that all ELEV cards be contiguous,
although the input file will be more readable if a logical order is followed. The network ID is also
not required to appear on each runstream image (except for the STA card). The model will
assume the previous ID if none is entered, similar to the use of continuation cards for pathway
and keywords. Thus, the following two examples produce the same 8X4 Cartesian grid
network:
RE
RE
RE
RE
RE
RE
RE
RE
RE
RE
RE
RE
RE
RE
RE
RE
RE
RE
GRIDCART
GRIDCART
GRIDCART
GRIDCART
GRIDCART
GRIDCART
GRIDCART
GRIDCART
GRIDCART
GRIDCART
GRIDCART
GRIDCART
GRIDCART
GRIDCART
GRIDCART
GRIDCART
GRIDCART
GRIDCART
CAR1
CAR1
CAR1
CAR1
CAR1
CAR1
CAR1
CAR1
CAR1
CAR1
CAR1
CAR1
CAR1
CAR1
CAR1
CAR1
CAR1
CAR1
STA
XPNTS
YPNTS
ELEV
ELEV
ELEV
ELEV
HILL
HILL
HILL
HILL
FLAG
FLAG
FLAG
FLAG
END
STA
XPNTS
YPNTS
ELEV
HILL
FLAG
ELEV
HILL
FLAG
ELEV
HILL
FLAG
ELEV
HILL
FLAG
END
1
2
3
4
1
2
3
4
1
2
3
4
1
1
1
2
2
2
3
3
3
4
4
4
-500.
-500.
10.
20.
30.
40.
50.
60.
70.
80.
10.
20.
30.
40.
-500.
-500.
8*10
8*50
8*10
8*20
8*60
8*20
8*30
8*70
8*30
8*40
8*80
8*40
-400
-250
10.
20.
30.
40.
50.
60.
70.
80.
10.
20.
30.
40.
-400
-250
10
20
30
40
50
60
70
80
10
20
30
40
-200 .
250 .
. 10.
. 20.
. 30.
. 40.
50.
60.
70.
80.
. 10.
. 20.
. 30.
. 40.
-200 .
250 .
-100.
500.
10.
20.
30.
40.
50.
60.
70.
80.
10.
20.
30.
40.
-100.
500.
100
10.
20.
30.
40.
50.
60.
70.
80.
10.
20.
30.
40.
100
2
10.
20.
30.
40.
50.
60.
70.
80.
10.
20.
30.
40.
2
00. 400. 500.
10.
20.
30.
40.
50.
60.
70.
80.
10.
20.
30.
40.
00. 400. 500.
The Row parameter on the ELEV. HILL, and FLAG inputs may be entered as either the
row number, i.e., 1, 2, etc., or as the actual y-coordinate value, e.g., -500., -250., etc. in the
example above. The model sorts the inputs using Row as the index, so the result is the same. The
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above example could therefore be entered as follows, with the same result:
RE GRIDCART CAR1 STA
XPNTS -500
YPNTS -500
ELEV -500
FLAG -500
ELEV -250
FLAG -250
ELEV 250
FLAG 250
ELEV 500
FLAG 500
RE GRIDCART CAR1 END
Of course, one must use either the row number or y-coordinate value consistently within each
network to have the desired result.
The following simple example illustrates the use of the XYINC secondary keyword to
generate a uniformly spaced Cartesian grid network. The resulting grid is 11 x 11, with a uniform
spacing of 1 kilometer (1000. meters), and is centered on the origin (0., 0.). No elevated terrain
heights or flagpole receptor heights are included in this example.
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3.4.1.2 Polar Grid Receptor Networks.
Polar receptor networks are defined by use of the GRIDPOLR keyword. The GRIDPOLR
keyword may also be thought of as a "sub-pathway," in that there are a series of secondary
keywords that are used to define the start and the end of the inputs for a particular network, and to
select the options for defining the receptor locations that make up the network. The syntax and
type of the GRIDPOLR keyword are summarized below:
Syntax:
Type:
RE GRIDPOLR Netid STA
ORIG
or ORIG
DIST
DDIR
or GDIR
ELEV
HILL
FLAG
END
Optional, Repeatable
Xinit
Srcid
Ringl
Dirl
Dirnum
Dir Z
Dir Z
Dir Z
Yinit ,
Ring2
Dir2
Dirini
elevl
hilll
flagl
Ring3
Dir3 .
Dirinc
Zelev2
Zhill2
Zflag2
. . . Ringn
. . Dirn,
Zelev3 . . .
Zhill3 . . .
Zflag3 ...
Zelevn
Zhilln
Zf lagn
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where the parameters are defined as follows:
Netid
STA
ORIG
Xinit
Yinit
Srcid
DIST
Ringl
Ringn
DDIR
Dirl
Dirn
GDIR
Dirnum
Dirini
Dirinc
ELEV
Dir
Zelev
HILL
Dir
Zelev
FLAG
Dir
Zflag
END
Receptor network identification code (up to eight alphanumeric
characters )
Indicates STArt of GRIDPOLR inputs for a particular network,
repeat for each new Netid
Keyword to specify the origin of the polar network (optional)
x-coordinate for origin of polar network
y-coordinate for origin of polar network
Source ID of source used as origin of polar network
Keyword to specify distances for the polar network
Distance to the first ring of polar coordinates
Distance to the 'nth' ring of polar coordinates
Keyword to specify discrete direction radials for the
polar network
First direction radial in degrees (1 to 360)
The 'nth' direction radial in degrees (1 to 360)
Keyword to specify generated direction radials for
the polar network
Number of directions used to define the polar system
Starting direction of the polar system
Increment (in degrees) for defining directions
Keyword to specify that receptor elevations follow (optional)
Indicates which direction is being input
An array of receptor terrain elevations for a
particular direction radial (default units of meters may be
changed to feet by use of RE ELEVUNIT keyword) ,
number of entries per radial equals the number of distances for
that network
Keyword to specify that hill height scales follow (optional)
Indicates which direction is being input
An array of receptor hill height scales for a
particular direction radial (default units of meters may be
changed to feet by use of RE ELEVUNIT keyword) ,
number of entries per radial equals the number of distances for
that network
Keyword to specify that flagpole receptor heights
follow (optional)
Indicates which direction is being input
An array of receptor heights above local terrain
elevation for a particular direction (flagpole
receptors )
Indicates END of GRIDPOLR subpathway, repeat for each
new Netid
The ORIG secondary keyword is optional for the GRIDPOLR inputs. If omitted, the
model assumes a default origin of (0., 0.,) in x,y coordinates. The ELEV. HILL, and FLAG
keywords are also optional inputs, and are only needed if elevated terrain or flagpole receptor
heights are to be used. If elevated terrain is being used, then both the ELEV and HILL inputs are
needed for each receptor. If the ELEV and HILL keywords are used and the model is being run
with the flat terrain option (see Section 3.2.2), then the elevated terrain height inputs will be
ignored by the model, and a non-fatal warning message will be generated. If the elevated terrain
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option is selected, and no elevated terrain heights are entered, the elevations will default to 0.0
meters, and warning messages will also be generated. The model handles flagpole receptor height
inputs in a similar manner.
As with the GRIDCART keyword described above, the order of cards within the
GRIDPOLR subpathway is not important, as long as all inputs for a particular network are
contiguous and start with the STA secondary keyword and end with the END secondary keyword.
It is not even required that all ELEV cards be contiguous, although the input file will be more
readable if a logical order is followed. The network ID is also not required to appear on each
runstream image (except for the STA card). The model will assume the previous ID if none is
entered, similar to the use of continuation cards for pathway and keywords.
The following example of the GRIDPOLR keyword generates a receptor network
consisting of 180 receptor points on five concentric distance rings centered on an assumed default
origin of (O.,0.). The receptor locations are placed along 36 direction radials, beginning with 10.
degrees and incrementing by 10. degrees in a clockwise fashion.
RE GRIDPOLR POL1 STA
DIST 100. 300. 500. 1000. 2000.
GDIR 36 10. 10.
RE GRIDPOLR POL1 END
Another example is provided illustrating the use of a non-zero origin, discrete direction
radials and the specification of elevated terrain and flagpole receptor heights:
RE GRIDPOLR POL1 STA
ORIG 500.
DIST 100.
DDIR 90.
ELEV 90. 5
ELEV 180. 5
ELEV 270. 5
ELEV 360. 5
HILL 90. 50
HILL 180. 50
HILL 270. 50
HILL 360. 50
FLAG 90. 5
FLAG 180. 5
FLAG 270. 5
FLAG 360. 5
RE GRIDPOLR POL1 END
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The user has the option of specifying the radial number (e.g. 1, 2, 3, etc.) on the ELEV. HILL.
and FLAG inputs, or the actual direction associated with each radial.
For purposes of model calculations, all receptor locations, including those specified as
polar, are stored in the model arrays as x, y and z coordinates and flagpole heights. For the
purposes of reporting the results by receptor in the main print file, the tables are labeled with the
polar inputs, i.e., directions and distances.
3.4.2 Using Multiple Receptor Networks
For some modeling applications, the user may need a fairly coarsely spaced network
covering a large area to identify the area of significant impacts for a plant, and a denser network
covering a smaller area to identify the maximum impacts. To accommodate this modeling need,
the AERMOD model allows the user to specify multiple receptor networks in a single model run.
The user can define either Cartesian grid networks or polar networks, or both. With the use of the
ORIG option in the GRIDPOLR keyword, the user can easily place a receptor network centered
on the facility being permitted, and also place a network centered on another background source
known to be a significant contributor to high concentrations. Alternatively, the polar network
may be centered on a receptor location of special concern, such as a nearby Class I area.
As noted in the introduction to this section (3.4), the model dynamically allocates array
storage based on the number of receptors and receptor networks when the AERMOD model is
run, up to the maximum amount of memory available on the computer.
3.4.3 Specifying Discrete Receptor Locations
In addition to the receptor networks defined by the GRTDCART and GRIDPOLR
keywords described above, the user may also specify discrete receptor points for modeling
impacts at specific locations of interest. This may be used to model critical receptors, such as the
locations of schools or houses, nearby Class I areas, or locations identified as having high
concentrations by previous modeling analyses. The discrete receptors may be input as either
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Cartesian x,y points (DISCCART keyword) or as polar distance and direction coordinates
(DISCPOLR keyword). Both types of receptors may be identified in a single run. In addition, for
discrete polar receptor points the user specifies the source whose location is used as the origin for
the receptor.
3.4.3.1 Discrete Cartesian Receptors.
Discrete Cartesian receptors are defined by use of the DISCCART keyword. The syntax
and type of this keyword are summarized below:
Syntax:
Type:
where the Xcoord and Ycoord parameters are the x-coordinate and y-coordinate (m), respectively,
for the receptor location. The Zelev parameter is an optional terrain elevation (m) and Zhill is a
corresponding hill height scale for the receptor for use in elevated terrain modeling. Both the
Zelev and Zhill parameters must be specified for use with the elevated terrain algorithms, and are
referenced to the same reference elevation (e.g., mean sea level) used for source elevations. The
Zflag parameter is the optional receptor height above ground (m) for modeling flagpole receptors.
All of the parameters are in units of meters, except for Zelev and Zhill, which default to meters
but may be specified in feet by use of the RE ELEVUNIT keyword.
If neither the elevated terrain option (Section 3.2.2) nor the flagpole receptor height option
(Section 3.2.7) are used, then the optional parameters are ignored if present. If only the elevated
terrain height option is used (no flagpoles), then the third parameter (the field after the Ycoord) is
read as the Zelev parameter. If only the flagpole receptor height option is used (no elevated
terrain), then the third parameter is read as the Zflag parameter. If both options are used, then the
parameters are read in the order indicated for the syntax above. If the optional parameters are left
blank, then default values will be used. The default value for Zelev is 0.0, and the default value
for Zflag is defined by the CO FLAGPOLE card (see Section 3.2.7). Note: If both the elevated
terrain and flagpole receptor height options are used, then the third parameter will always be used
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as Zelev, and it is not possible to use a default value for Zelev while entering a specific value for
the Zflag parameter.
3.4.3.2 Discrete Polar Receptors.
Discrete polar receptors are defined by use of the DISCPOLR keyword. The syntax and
type of this keyword are summarized below:
Syntax:
Type:
Optional, Repeatable
where the Srcid is the alphanumeric source identification for one of the sources defined on the SO
pathway which will be used to define the origin for the polar receptor location. The Dist and
Direct parameters are the distance in meters and direction in degrees for the discrete receptor
location. Degrees are measured clockwise from north. The Zelev parameter is an optional terrain
elevation for the receptor and Zhill is the corresponding hill top elevation (m) for use in elevated
terrain modeling. Both the Zelev and Zhill parameters must be specified for use with the elevated
terrain algorithms, and are referenced to the same reference elevation (e.g., mean sea level) used
for source elevations. The units of Zelev and Zhill are in meters, unless specified as feet by the
RE ELEVUNIT keyword. The Zflag parameter is the optional receptor height above ground
(meters) for modeling flagpole receptors.
If neither the elevated terrain option (Section 3.2.2) nor the flagpole receptor height option
(Section 3.2.7) are used, then the optional parameters are ignored if present. If only the elevated
terrain height option is used (no flagpoles), then the third parameter (the field after the Ycoord) is
read as the Zelev parameter. If only the flagpole receptor height option is used (no elevated
terrain), then the third parameter is read as the Zflag parameter. If both options are used, then the
parameters are read in the order indicated for the syntax above. If the optional parameters are left
blank, then default values will be used. The default value for Zelev is 0.0, and the default value
for Zflag is defined by the CO FLAGPOLE card (see Section 3.2.7). Note: If both the elevated
terrain and flagpole receptor height options are used, then fourth parameter will always be used as
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Zelev, and it is not possible to use a default value for Zelev while entering a specific value for the
Zflag parameter.
3.4.3.3 Discrete Cartesian Receptors for EVALFILE Output.
The EVALCART keyword is used to define discrete Cartesian receptor locations, similar
to the DISCCART keyword, but it also allows for grouping of receptors, e.g., along arcs. It is
designed to be used with the EVALFILE option, described later for the output pathway, which
outputs arc maxima values to a separate file for evaluation purposes. The EVALCART keyword
can be used without the use of the EVALFILE option, in which case the receptor groupings are
ignored. The syntax and type for the modified EVALCART keyword are summarized below:
Syntax:
Type:
where the Xcoord and Ycoord parameters are the x-coordinate and y-coordinate (m), respectively,
for the receptor location. The Zelev parameter is the terrain elevation (m) for the receptor and
Zhill is the corresponding hill top elevation (m) for use in elevated terrain modeling. Both the
Zelev and Zhill parameters must be specified for use with the elevated terrain algorithms, and are
referenced to the same reference elevation (e.g., mean sea level) used for source elevations. The
Zflag parameter is the receptor height above ground (m) for modeling flagpole receptors. All of
the parameters are in units of meters, except for Zelev and Zhill, which default to meters but may
be specified in feet by use of the RE ELEVUNIT keyword. The Arcid parameter is the receptor
grouping identification, which may be up to eight characters long, and may be used to group
receptors by arc. The Name parameter is an optional name field that may be included to further
identify a particular receptor location. The Name parameter is ignored by the model. Unlike the
DISCCART keyword, all of the parameters (except for the Name) must be present on each card
with the EVALCART keyword. The terrain height and flagpole height inputs are ignored if the
appropriate options are not specified on the CO TERRHGHT and CO FLAGPOLE cards.
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3.4.4 Including Receptor Data From an External File
The user has the option of including receptor data from an external file by using the
INCLUDED keyword on the receptor pathway. An RE INCLUDED card may be placed
anywhere within the source pathway, after the STARTING card and before the FINISHED card
(i.e., the RE STARTING and RE FINISHED cards cannot be included in the external file). The
data in the included file will be processed as though it were part of the runstream file. The syntax
and type of the INCLUDED keyword are summarized below:
Syntax:
RE INCLUDED Incfil
Type:
Optional, Repeatable
where the Incfil parameter is a character field of up to 40 characters that identifies the filename
for the included file. The contents of the included file must be valid runstream images for the
receptor pathway. If an error is generated during processing of the included file, the error
message will report the line number of the included file (see Appendix C). If more than one
INCLUDED file is specified for the receptor pathway, the user will first need to determine which
file the error occurred in. If the starting column of the main runstream input file is shifted from
column 1 (see Section 2.4.8), then the runstream images in the included file must be offset by the
same amount. The INCLUDED option allows the user to include receptor data that have been
generated by the AERMOD Terrain Preprocessor, AERMAP, in the runstream file without having
to cut and paste the AERMAP output file. Since AERMAP generates terrain elevations in meters
and includes the RE ELEVUNIT METERS card as the first record, an AERMAP file must be
INCLUDED at the beginning of the receptor pathway, immediately following the RE STARTING
card. If more than one AERMAP output file is INCLUDED on the receptor pathway, the RE
ELEVUNIT METERS card must be deleted from all but the first one.
3.5 METEOROLOGY PATHWAY INPUTS AND OPTIONS
The MEteorology pathway contains keywords that define the input meteorological data
for a particular model run.
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3.5.1 Specifying the Input Data Files and Formats
The AERMOD model uses hourly meteorological data from separate surface and
profile data files as one of the basic model inputs. These input meteorological data filenames for
AERMOD are identified by the SURFFILE and PROFFILE keywords on the ME pathway. The
syntax and type of these keywords are summarized below:
Syntax:
ME SURFFILE Sfcfil (Format)
ME PROFFILE Profil (Format)
Type:
where the Srcfil and Profil parameters are character fields of up to 40 characters that identify the
filenames for the input meteorological data files. For running the model on an IBM-compatible
PC, the filename parameters may include the complete DOS pathname for the file, or will assume
the current directory if only the filename is given. The optional Format parameter specifies the
format of the meteorological data files. The default formats for the surface and profile data files
corresponds with the format of the files generated by the AERMET meteorological preprocessor
program. The user also has the option of specifying the Fortran read format for each of these
files. The contents of the meteorological data files are described below, and the file formats are
documented in Appendix D.
The surface meteorological data file consists of a header record containing information on
the meteorological station locations, and one record for each hour of data. These data are
delimited by at least one space between each element, i.e., the data may be read as free format.
The contents of the surface file are as follows:
Year
Month (1-12)
Day (1-31)
Julian day (1 - 366)
Hour (1-24)
Sensible heat flux (W m'2)
Surface friction velocity, u» (ms"1)
Convective velocity scale, w* (ms"1)
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Vertical potential temperature gradient in the 500 m layer above the planetary boundary
layer
Height of the convectively-generated boundary layer (m)
Height of the mechanically-generated boundary layer (m)
Monin-Obukhov length, L (m)
Surface roughness length, z0 (m)
Bowen ratio
Albedo
Wind speed (ms"1) used in the computations
Wind direction (degrees) corresponding to the wind speed above
Height at which the wind above was measured (m)
Temperature (K) used in the computations
Height at which the temperature above was measured (m)
The sensible heat flux, Bowen ratio and albedo are not used by the AERMOD model, but are
passed through by AERMET for information purposes only.
The profile meteorological data file consists of one or more records for each hour of data.
As with the surface data file, the data are delimited by at least one space between each element
and may be read as Fortran free format. The contents of the profile meteorological data file are as
follows:
Year
Month (1-12)
Day (1 -31)
Hour (1-24)
Measurement height (m)
Top flag = 1, if this is the last (highest) level for this hour,
0, otherwise
Wind direction for the current level (degrees)
Wind speed for the current level (ms"1)
Temperature at the current level (K)
Standard deviation of the wind direction, oe (degrees)
Standard deviation of the vertical wind speed, ow (ms"1)
The data in this file include the on-site meteorological data that are processed by
AERMET. Since AERMET was designed to be able to perform dispersion parameter calculations
with NWS data only, i.e., no on-site data, the profile data may consist of a one-level "profile"
based on the NWS winds and temperature.
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3.5.2 Specifying Station Information
Three keywords are used to specify information about the meteorological stations,
SUKFDATA for the surface meteorological station, UAIRDATA for the upper air station, and the
optional SITED ATA for any on-site meteorological data that may be used. The syntax and type
of these keywords are summarized below:
Syntax:
Syntax:
Syntax:
Type:
ME
ME
ME
SURFDATA
UAIRDATA
SITEDATA
Stanum
Stanum
Stanum
Y
Y
ear
ear
Year
Mandatory, Non-repeatable
Optional, Non-repeatable f
(Name )
(Name )
(Name)
(Xco
(Xco
ord)
ord)
(Xcoord)
for SURFDATA
or SITEDATA
and
(Yco
(Yco
ord)
ord)
(Ycoord)
UAIRDATA
where Stanum is the station number, e.g. the 5-digit WB AN number for NWS stations, Year is the
year of data being processed (either 2 or 4 digits), Name is an optional character field (up to 40
characters with no blanks) specifying the name of the station, and Xcoord and Ycoord are
optional parameters for specifying the x and y coordinates for the location of the stations. At the
present time, the station locations are not utilized in the model. Therefore, no units are specified
for Xcoord and Ycoord at this time, although meters are suggested in order to be consistent with
the source and receptor coordinates. The AERMOD model compares the station numbers input
using these keywords with the numbers included in the header record of the surface
meteorological data file, and issues non-fatal warning messages if there are any mismatches.
3.5.3 Specifying the Base Elevation for Potential Temperature Profile
The AERMOD model generates a gridded vertical profile of potential temperatures for use
in the plume rise calculations. Since potential temperature is dependent on the elevation above
mean sea level (MSL), the user must define the base elevation for the profile with the
PROFBASE keyword. The syntax and type for the PROFBASE keyword are summarized below:
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Syntax:
ME PROFBASE BaseElev (Units)
Type:
Mandatory, Non-repeatable
where the BaseElev parameter specifies the base elevation above MSL for the potential
temperature profile, and the optional Units parameter specifies the units of BaseElev. Valid
inputs of Units are the secondary keywords METERS or FEET. The default units for BaseElev
are in meters if Units is left blank. The base elevation should correspond with the base elevation
of the primary meteorological tower.
3.5.4 Specifying a Data Period to Process
There are two keywords that allow the user to specify particular days or ranges of days to
process from the sequential meteorological file input for the AERMOD model. The STARTEND
keyword controls which period within the meteorological data file is read by the model, while the
DAYRANGE keyword controls which days or ranges of days (of those that are read) for the
model to process. The default for the model is to read the entire meteorological data file (up to a
full year) and to process all days within that period.
The syntax and type for the STARTEND keyword are summarized below:
Syntax:
. ME STARTEND Strtyr Strtmn Strtdy (Strthr) Endyr Endmn Enddy (Endhr;
Type:
Optional, Non-repeatable
where the Strtyr Strtmn Strtdy parameters specify the year, month and day of the first record to be
read (e.g., 87 01 31 for January 31, 1987), and the parameters Endyr Endmn Enddy specify the
year, month and day of the last record to be read. The Strthr and Endhr are optional parameters
that may be used to specify the start and end hours for the data period to be read. If either Strthr
or Endhr is to be specified, then both must be specified. Any records in the data file that occur
before the start date are ignored, as are any records in the data file that occur after the end date.
In fact, once the end date has been reached, the model does not read any more data from the
meteorological file. If Strthr and Endhr are not specified, then processing begins with hour 1 of
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the start date, and ends with hour 24 of the end date, unless specific days are selected by the
DAYRANGE card described below.
Any PERIOD averages calculated by the model will apply only to the period of data
actually processed. Therefore, if someone wanted to calculate a six-month average, they could
select PERIOD averages on the CO AVERTIME card, and then specify the period as follows:
for the period January 1, 1987 through June 30, 1987.
The syntax and type for the DAYRANGE keyword are summarized below:
Syntax:
Type:
where the Range parameters specify particular days or ranges of days to process. The days may
be specified as individual days (e.g. 1 2 3 4 5) or as a range of days (e.g. 1-5). The user also has
the option of specifying Julian day numbers, from 1 to 365 (366 for leap years), or specifying
month and day (e.g., 1/31 for January 31). Any combination of these may also be used. For
example the following card will tell the model to process the days from January 1 (Julian day 1)
through January 31 (1/31):
ME DAYRANGE 1-1/31
The DAYRANGE keyword is also repeatable, so that as many cards as needed may be included
in the ME pathway.
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As with the STARTEND keyword, any PERIOD averages calculated by the model will
apply only to the period of data actually processed. If the STARTEND keyword is also used,
then only those days selected on the DAYRANGE cards that fall within the period from the start
date to the end date will be processed. Thus, if the ME pathway included the following two
cards:
ME STARTEND 87 02 01 87 12 31
ME DAYRANGE 1-31
then no data would be processed, since the days 1 through 31 fall outside the period 2/1 to 12/31.
3.5.5 Correcting Wind Direction Alignment Problems
The WDROTATE keyword allows the user to correct the input meteorological data for
wind direction alignment problems. All input wind directions or flow vectors are rotated by a
user-specified amount. Since the model results at particular receptor locations are often quite
sensitive to the transport wind direction, this optional keyword should be used only with extreme
caution and with clear justification.
The syntax and type of this keyword are summarized below:
Syntax:
ME WDROTATE Rotang
Type:
Optional, Non-repeatable
where the Rotang parameter specifies the angle in degrees to rotate the input wind direction
measurements. The value of Rotang is subtracted from the wind direction measurements. It may
be used to correct for known (and documented) calibration errors, or to adjust for the alignment of
a valley if the meteorological station is located in a valley with a different alignment than the
source location.
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3.5.6 Specifying Wind Speed Categories
Variable emission rate factors may be input to the model that vary by wind speed
category. The model uses six wind speed categories, and these are defined by the upper bound
wind speed for the first five categories (the sixth category is assumed to have no upper bound).
The default values for the wind speed categories are as follows: 1.54, 3.09, 5.14, 8.23, and 10.8
m/s. The syntax and type of the WINDCATS keyword, which may be used to specify different
category boundaries, are summarized below:
Syntax:
Type:
Optional, Non-repeatable
where the Wsl through Ws5 parameters are the upper bound wind speeds of the first through fifth
categories in meters per second. The upper bound values are inclusive, i.e., a wind speed equal to
the value of Wsl will be placed in the first wind speed category.
3.5.7 Specifying SCIM Parameters
The SCIM parameters on the SCIMBYHR card specify the starting hour and sampling
interval for the regular sample and an optional file name. The syntax and type of the
SCIMBYHR keyword are summarized below:
Syntax:
ME SCIMBYHR NRegStart NReglnt NwetStart Nwetlnt (SfcFilnam PflFilnam)
Type:
where the NRegStart and NReglnt parameters specify the first hour to be sampled and the
sampling interval, respectively, when performing the regular sampling. The NWetStart and
NWetlnt parameters are used to specify the first wet hour (i.e., with non-zero precipitation) and
the wet sampling interval for wet sampling. However, since the AERMOD model currently does
not include wet deposition algorithms, the wet sampling option is not operational, and the user
should enter a value of zero (0) for bot NWetStart and NWetlnt. Optionally, the user can create
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output files containing the surface and profile meteorological data for the sampled hours by
specifying the SfcFilnam and PflFilnam parameters. These output files are in the same format
used in the summary of the first 24 hours of data included in the main output file.
In order to use the SCIM option, the user must specify the non-DFAULT TOXICS option
on the CO MODELOPT card, and also specify SCIM on the MODELOPT card. Although the
ME SCIMBYHR is an optional card, it is required when using the SCIM option. NRegStart is
required to have a value from 1 through 24, i.e., the first sampled hour must be on the first day in
the meteorological data file. There are no restrictions for NReglnt; however, NReglnt would
generally be greater than 1. For example, NReglnt could be based on the formula (24n+l), where
"n" is the number of days to skip between samples, in order to ensure a regular diurnal cycle to
the sampled hours (e.g., 25 or 49).
3.6 EVENT PATHWAY INPUTS AND OPTIONS
EVENT processing is specifically designed to facilitate analysis of source contributions to
specific events for short term averages (less than or equal to 24 hours). These events may be
design concentrations generated by the AERMOD model, occurrences of violations of an air
quality standard, or user-specified events. These events are input to the AERMOD model
through the EVent pathway. Each event is defined by an averaging period and specific data
period, a source group, and a receptor location. Since the locations are only of interest in
combination with particular averaging and data periods, the REceptor pathway is not used with
EVENT processing.
There are two keywords that are used to define the events on the EV pathway. The
EVENTPER keyword defines the averaging period, data period and source group, while the
EVENTLOC keyword defines the receptor location for the event. Each event is also given an
alphanumeric name that links the two input cards for that event.
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The syntax and type of the EVENTPER and EVENTLOC keywords are summarized
below:
Syntax: EV EVENTPER Evname Aveper Grpid Date
Syntax:
EV EVENTLOC Evname XR= Xr YR= Yr (Zelev)
or Evname RNG= Rng DIR= Dir (Zelev)
Type:
Mandatory, Repeatable
where the parameters are as follows:
Evname - event name (an alphanumeric string of up to 8 characters),
Aveper - averaging period for the event (e.g. J_,3., .8, 24 hr)
Grpid - source group ID for the event (must be defined on SO pathway),
Date - date for the event, input as an eight digit integer for the ending hour of the
data period (YYMMDDHH), e.g. 84030324 defines a data period ending at
hour 24 on March 3, 1984. The length of the period corresponds to Aveper.
XR= - X-coordinate (m) for the event location, referenced to a Cartesian coordinate
system
YR= - Y-coordinate (m) for the event location, referenced to a Cartesian coordinate
system
RNG= - distance range (m) for the event location, referenced to a polar coordinate
system with an origin of (0., 0.)
DIR= - radial direction (deg.) for the event location, referenced to a polar coordinate
system with an origin of (0., 0.)
Zelev - optional terrain elevation for the event location (m)
Zflag - optional receptor height above ground (flagpole receptor) for the event
location (m)
Each event is defined by the two input cards EVENTPER and EVENTLOC, and these inputs are
linked by the event name, which must be unique among the events being processed in a given run.
There is no particular requirement for the order of cards on the EV pathway. Note that the
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location for the event may be specified by either Cartesian coordinates or by polar coordinates,
however, the polar coordinates must be relative to an origin of (0,0).
3.6.1 Using Events Generated by the AERMOD Model
The AERMOD model has an option (CO EVENTFIL described in Section 3.2.9) to
generate an input file for the AERMOD EVENT processing. When this option is used, the
AERMOD model copies relevant inputs from the AERMOD runstream input file to the Event
processing input file, and generates the inputs for the EVent pathway from the results of the
modeling run. These events are the design concentrations identified by the OU RECTABLE
keyword (see Section 3.8.1.1), such as the highest and high-second-high 24-hour averages, etc.,
and any threshold violations identified by the OU MAXIFILE keyword (see Section 3.8.1.2). The
inputs generated by the AERMOD model correspond to the syntax described above for the
EVENTPER and EVENTLOC keywords. The locations for events generated by the AERMOD
model are always provided as Cartesian coordinates.
To easily identify the events generated by the AERMOD model, and to provide a
mechanism for the AERMOD model to manage the events generated from the model run, a
naming convention is used for the EVNAME parameter. The following examples illustrate the
event names used by the AERMOD model:
H1H01001 - High-first-high 1-hour average for source group number 1
H2H24003 - High-second-high 24-hour average for source group number 3
TH030010 - Threshold violation number 10 for 3-hour averages
TH240019 - Threshold violation number 19 for 24-hour averages
The high value design concentrations are listed first in the EVENT processing input file, followed
by the threshold violations (grouped by averaging period). To make it easier for the user to
review the EVENT processing input file generated by the AERMOD model, and determine which
events are of most concern, the actual concentration value associated with the event is included as
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the last field on the EVENTPER card. This field is ignored by the AERMOD model, and is
included only for informational purposes. The user should be aware that the same event may
appear in the AERMOD model input file as both a design value and as a threshold violation,
depending on the options selected and the actual results. Since the model processes the events by
date sequence and outputs the results for each event as it is processed, the order of events in the
output file will generally not follow the order of events in the input file, unless all of the events
were generated by the MAXIFILE option.
3.6.2 Specifying Discrete Events
The user can specify discrete events by entering the EVENTPER and EVENTLOC cards
as described above. The averaging period and source group selected for the event must be among
those specified on the CO AVERTEVIE and SO SRC GROUP cards. If the EVENT processing
input file was generated by the AERMOD model, the user may include additional events for those
averaging periods and source groups used in the original AERMOD model run. They may also
add averaging periods or define new source groups in the Event processing input file in order to
define additional events.
3.6.3 Including Event Data From an External File
The user has the option of including event data from an external file by using the
INCLUDED keyword on the source (EV) pathway. An EV INCLUDED card may be placed
anywhere within the event pathway, after the STARTING card and before the FINISHED card
(i.e., the EV STARTING and EV FINISHED cards cannot be included in the external file). The
data in the included file will be processed as though it were part of the runstream file. The syntax
and type of the INCLUDED keyword are summarized below:
Syntax:
EV INCLUDED Incfil
Type:
Optional, Repeatable
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where the Incfil parameter is a character field of up to 40 characters that identifies the filename
for the included file. The contents of the included file must be valid runstream images for the
event pathway. If an error is generated during processing of the included file, the error message
will report the line number of the included file (see Appendix C). If more than one INCLUDED
file is specified for the event pathway, the user will first need to determine which file the error
occurred in. If the starting column of the main runstream input file is shifted from column 1 (see
Section 2.4.8), then the runstream images in the included file must be offset by the same amount.
3.7 OUTPUT PATHWAY INPUTS AND OPTIONS
The OUtput pathway contains keywords that define the output options for the model
runs. The AERMOD model has three keywords that control different types of tabular output for
the main output file of the model, and seven keywords that control separate output file options for
specialized purposes. The user may select any combination of output option for a particular
application.
3.7.1 Selecting Options for Tabular Printed Outputs.
The three tabular printed output options are controlled by the following keywords:
RECTABLE - Controls output option for high value summary tables by receptor;
MAXTABLE - Controls output option for overall maximum value summary tables; and
DAYTABLE - Controls output option for tables of concurrent values summarized by
receptor for each day processed.
The keywords are described in more detail in the order listed above.
The syntax and type for the RECTABLE keyword are summarized below:
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Syntax:
OU RECTABLE Aveper FIRST SECOND ... SIXTH or 1ST 2ND ... 6TH
Type:
Optional, Repeatable
where the Aveper parameter is the short term averaging period (e.g. 1, 3_, £ or 24 hr or MONTH)
for which the receptor table is selected, and the secondary keywords, FIRST. SECOND, etc.,
indicate which high values are to be summarized by receptor for that averaging period. The
RECTABLE card may be repeated for each averaging period. For cases where the user wants the
same RECTABLE options for all short term averaging periods being modeled, the input may be
simplified by entering the secondary keyword ALLAVE for the Aveper parameter. The
following example will select summaries of the highest, second highest and third highest values
by receptor for all averaging periods:
OU RECTABLE ALLAVE FIRST SECOND THIRD
The model will also recognize a range of high values on the RECTABLE input card, and
therefore the following card will have the effect:
OU RECTABLE ALLAVE FIRST-THIRD
The output file will include tables for only the high values selected. Tables for all source
groups for a particular averaging period are grouped together, and the averaging periods are
output in the order that they appear the CO AVERTEVIE card. For each averaging period and
source group combination, the tables of high values for the receptor networks (if any) are printed
first, followed by any discrete Cartesian receptors, and any discrete polar receptors.
If the CO EVENTFIL keyword has been used to generate an input file for EVENT
processing, then the design values identified by the RECTABLE options, e.g., the
high-second-high 24-hour average, are included in the events that are defined in the EVENT
processing input file.
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The syntax and type for the MAXTABLE keyword are summarized below:
Syntax:
OU MAXTABLE Aveper Maxnum
Type:
Optional, Repeatable
where the Aveper parameter is the short term averaging period (e.g. 1, 3_, £ or 24 hr or MONTH)
for which the receptor table is selected, and the Maxnum parameter specifies the number of
overall maximum values to be summarized for each averaging period. The MAXTABLE card
may be repeated for each averaging period. As with the RECTABLE keyword, for cases where
the user wants the same MAXTABLE options for all short term averaging periods being modeled,
the input may be simplified by entering the secondary keyword ALLAVE for the Aveper
parameter. The following example will select the maximum 50 table for all averaging periods:
OU MAXTABLE ALLAVE 50
A separate maximum overall value table is produced for each source group. The
maximum value tables follow the RECTABLE outputs in the main print file. All source group
tables for a particular averaging period are grouped together, and the averaging periods are output
in the order that they appear on the CO AVERTIME card.
The syntax and type for the DAYTABLE keyword are summarized below:
Syntax:
OU DAYTABLE Avperl Avper2 Avper3
Type:
Optional, Non-repeatable
where the Avpern parameters are the short term averaging periods (e.g. J_,1, 8 or 24 hr or
MONTH) for which the daily tables are selected. The DAYTABLE card is non-repeatable, but as
with the RECTABLE and MAXTABLE keywords, for cases where the user wants daily tables for
all short term averaging periods being modeled, the input may be simplified by entering the
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secondary keyword ALLAVE for the first parameter. The following example will select the daily
tables for all averaging periods:
OU DAY TABLE ALLAVE
For each averaging period for which the DAYTABLE option is selected, the model will
print the concurrent averages for all receptors for each day of data processed. The receptor
networks (if any) are printed first, followed by any discrete Cartesian receptors, and any discrete
polar receptors. Results for each source group are output. For example, if 1, 3, and 24-hour
averages are calculated, and the OU DAYTABLE ALLAVE option is used, then for the first day
of data processed, there will be 24 sets of tables of hourly averages (one for each hour in the day),
eight sets of 3-hour averages (one for each 3-hour period in the day), and one set of 24-hour
averages. The averages are printed as they are calculated by the model, but for hours where more
than one averaging period is calculated (e.g., hour 24 is the end of an hourly average, a 3-hour
average, and a 24-hour average), the order in which the averages are output will follow the order
used on the CO AVERTIME card. Note: This option can produce very large output files,
especially when used with a full year of data and very short period averages, such 1-hour and
3-hour. It should therefore be used with CAUTION.
3.7.2 Selecting Options for Special Purpose Output Files.
The AERMOD model provides options for seven types of output files for specialized
purposes. These options are controlled by the following keywords:
MAXIFILE - Produces file with occurrences of violations of user-specified threshold
value;
POSTFILE - Produces file of concurrent (raw) results at each receptor suitable for
post-processing;
PLOTFILE - Produces file of design values that can be imported into graphics software
for plotting contours;
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TOXXFILE - Produces unformatted files of raw results above a threshold value with a
special structure for use with the TOXX model component of TOXST;
RANKFILE - Produces file of output values by rank for use in Q-Q (quantile) plots;
EVALFILE - Produces file of output values, including arc-maximum normalized
concentrations, suitable for model evaluation studies; and
SEASONHR - Produces file of output values by season and hour-of-day.
The keywords are described in more detail in the order listed above.
The syntax and type for the MAXIFILE keyword are summarized below:
Syntax:
OU MAXIFILE Aveper Grpid Thresh Filnam (Funit)
Type:
Optional, Repeatable
where the Aveper parameter is the short term averaging period (e.g. 3_, 8, 24 for 3, 8 and 24-hour
averages, or MONTH for monthly averages) and Grpid is the source group ID for which the
MAXIFILE option is selected. The Thresh parameter is the user-specified threshold value, and
Filnam is the name of the file where the MAXIFILE results are to be written. The optional Funit
parameter allows the user the option of specifying the Fortran logical file unit for the output file.
The user-specified file unit must be in the range of 26-100, inclusive. By specifying the same
filename and unit for more than one MAXIFILE card, results for different source groups and/or
averaging periods may be combined into a single file. If the Funit parameter is omitted, then the
model will dynamically allocate a unique file unit for this file (see Section 3.7.2).
The MAXIFILE card may be repeated for each combination of averaging period and
source group, and a different filename should be used for each file. The resulting maximum value
file will include several header records identifying the averaging period, source group and the
threshold value for that file, and a listing of every occurrence where the result for that averaging
period/source group equals or exceeds the threshold value. Each of these records includes the
averaging period, source group ID, date for the threshold violation (ending hour of the averaging
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period), the x, y, z and flagpole receptor height for the receptor location where the violation
occurred, and the concentration value.
Each of the threshold violations, except for monthly averages, identify events that may be
modeled for source contribution information with EVENT processing by selecting the CO
EVENTFIL option (see Sections 3.2.9 and 3.8). Each of the threshold violations is included as an
event on the EV pathway, and is given a name of the form THxxyyyy, where xx is the averaging
period, and yyyy is the violation number for that averaging period. For example, an event name
of TH240019 identifies the 19th threshold violation for 24-hour averages. Monthly average
threshold violations are included in the file specified on the MAXIFILE card, but are not included
in the EVENT processing input file since the AERMOD model currently handles only averaging
periods of up to 24 hours.
The following examples illustrate the use of the MAXIFILE option:
OU MAXIFILE 24 ALL 364.0 MAX24ALL.OUT
OU MAXIFILE 24 PSD 91.0 MAXPSD.OUT 50
OU MAXIFILE 3 PSD 365.0 MAXPSD.OUT 50
OU MAXIFILE 3 PLANT 25.0 C:\OUTPUT\MAXI3HR.FIL
OU MAXIFILE MONTH ALL 10.0 MAXMONTH.OUT
where the 3-hour example illustrates the use of a DOS pathname for the PC, and the last example
illustrates the use of monthly averages. The FILNAM parameter may be up to 40 characters in
length. It should also be noted that only one MAXIFILE card may be used for each averaging
period/source group combination. Note: The MAXIFILE option may produce very large files for
runs involving a large number of receptors if a significant percentage of the results exceed the
threshold value.
The syntax and type for the POSTFILE keyword are summarized below:
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Syntax:
OU POSTFILE Aveper Grpid Format Filnam (Funit)
Type:
Optional, Repeatable
where the Aveper parameter is the averaging period (e.g. 3_, .8, 24 for 3, 8 and 24-hour averages,
MONTH for monthly averages, PERIOD for period averages, or ANNUAL for annual averages)
and Grpid is the source group ID for which the POSTFILE option is selected. The Format
parameter specifies the format of the POSTFILE output, and may either be the secondary
keyword UNIFORM for unformatted concentration files, or the secondary keyword PLOT to
obtain formatted files of receptor locations (x- and y-coordinates) and concentrations suitable for
plotting contours of concurrent values. The Filnam parameter is the name of the file where the
POSTFILE results are to be written. The optional Funit parameter allows the user the option of
specifying the Fortran logical file unit for the output file. The user-specified file unit must be in
the range of 26-100, inclusive. By specifying the same filename and unit for more than one
POSTFILE card, results for different source groups and/or averaging periods may be combined
into a single file. If the Funit parameter is omitted, then the model will dynamically allocate a
unique file unit for this file (see Section 3.8.2).
The POSTFILE card may be repeated for each combination of averaging period and
source group, and a different filename should be used for each file. IfUNFORM is specified for
the Format parameter, then the resulting unformatted file includes a constant-length record for
each of the selected averaging periods calculated during the model run. The first variable of each
record is an integer variable (4 bytes) containing the ending date (YYMMDDHH) for the
averages on that record. The second variable for each record is an integer variable (4 bytes) for
the number of hours in the averaging period. The third variable for each record is a character
variable of length eight containing the source group ID. The remaining variables of each record
contain the calculated average concentration values for all receptors, in the order in which they
were defined in the input runstream.
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The following examples illustrate the use of the POSTFILE option:
OU POSTFILE 24 ALL UNFORM PST24ALL.BIN
OU POSTFILE 24 PSD UNFORM PST24PSD.BIN
OU POSTFILE 3 PLANT UNFORM C:\BINOUT\PST3HR.FIL
OU POSTFILE MONTH ALL PLOT PSTMONTH.PLT
OU POSTFILE PERIOD ALL PLOT PSTANN.PLT
where the 3-hour example illustrates the use of a DOS pathname for the PC, and the last example
illustrates the use of monthly averages. The Filnam parameter may be up to 40 characters in
length. The use of separate files for each averaging period/source group combination allows the
user flexibility to select only those results that are needed for post-processing for a particular run,
and also makes the resulting unformatted files manageable. Note: The POSTFILE option can
produce very large files, and should be used with some caution. For a file of hourly values for a
full year (8760 records) and 400 receptors, the resulting file will use about 14 megabytes of disk
space. To estimate the size of the file (in bytes), use the following equation:
(# of Hrs/Yr)
File Size (bytes) = * (# of Rec + 4) * 4
(# of Hrs/Ave)
Divide the result by 1000 to estimate the number of kilobytes (KB) and divide by 1.0E6 to
estimate the number of megabytes (MB).
The syntax and type for the PLOTFILE keyword are summarized below:
OU PLOTFILE Aveper Grpid Hivalu Filnam (Funit), or
OU PLOTFILE PERIOD Grpid Filnam (Funit)
OU PLOTFILE ANNUAL Grpid Filnam (Funit)
Type:
Optional, Repeatable
where the Aveper parameter is the averaging period (e.g. 3_, 8, 24 for 3, 8 and 24-hour averages,
MONTH for monthly averages, PERIOD for period averages, or ANNUAL for annual averages),
Grpid is the source group ID for which the PLOTFILE option is selected, and Hivalu specifies
which short term high values are to be output (FIRST for the first highest at each receptor,
SECOND for the second highest at each receptor, etc.) Note that the Hivalu parameter is not
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specified for PERIOD or ANNUAL averages, since there is only one period or annual average for
each receptor. The Filnam parameter is the name of the file where the PLOTFILE results are to
be written. The optional Funit parameter allows the user the option of specifying the Fortran
logical file unit for the output file. The user-specified file unit must be in the range of 26-100,
inclusive. By specifying the same filename and unit for more than one PLOTFILE card, results
for different source groups and/or averaging periods may be combined into a single file. If the
Funit parameter is omitted, then the model will dynamically allocate a unique file unit for this file
(see Section 3.8.2).
The PLOTFILE card may be repeated for each combination of averaging period, source
group, and high value, and a different filename should be used for each file. The resulting
formatted file includes several records with header information identifying the averaging period,
source group and high value number of the results, and then a record for each receptor which
contains the x and y coordinates for the receptor location, the appropriate high value at that
location, and the averaging period, source group and high value number. The data are written to
the file in the order of x-coord, y-coord, concentration so that the file can easily be imported into
a graphics package designed to generate contour plots. Many such programs will read the
PLOTFILEs directly without any modification, ignoring the header records, and produce the
desired plots.
The following examples illustrate the use of the PLOTFILE option:
OU PLOTFILE 24 ALL FIRST PLT24ALL.FST
OU PLOTFILE 24 ALL SECOND PLT24ALL.SEC
OU PLOTFILE 24 PSD 2ND PLTPSD.OUT 75
OU PLOTFILE 3 PSD 2ND PLTPSD.OUT 75
OU PLOTFILE 3 PLANT 1ST C:\PLOTS\PLT3HR.FIL
OU PLOTFILE MONTH ALL THIRD PLTMONTH.OUT
OU PLOTFILE PERIOD ALL PSTANN.PLT
where the 3-hour example illustrates the use of a DOS pathname for the PC, and the last example
illustrates the use of monthly averages. As illustrated by the second and third examples, the high
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value parameter may also be input as secondary keywords using the standard abbreviations of
1ST. 2ND. 3RD. . . . 10TH. The Filnam parameter may be up to 40 characters in length. The
use of separate files for each averaging period, source group, high value combination allows the
user flexibility to select only those results that are needed for plotting from a particular run.
The syntax and type for the TOXXFILE keyword are summarized below:
Syntax:
Type:
OU TOXXFILE Aveper Cutoff Filnam
Optional, Repeatable
(Funit)
where the Aveper parameter is the short term averaging period (e.g. 1, 3_, 8, 24 for 1, 3, 8 and
24-hour averages, or MONTH for monthly averages) for which the TOXXFILE option has been
selected. The Cutoff (threshold) parameter is the user-specified threshold cutoff value in g/m3,
and Filnam is the name of the file where the TOXXFILE results are to be written. It is important
to note that the units of the Cutoff parameter are g/m3, regardless of the input and output units
selected with the SO EMISUNIT card. The optional Funit parameter allows the user the option of
specifying the Fortran logical file unit for the output file. The user-specified file unit must be in
the range of 26-100, inclusive. If the Funit parameter is omitted, then the model will dynamically
allocate a unique file unit for this file (see Section 3.8.2). While the TOXXFILE option may be
specified for any of the short term averaging periods that are identified on the CO AVERTIME
card for a particular run, a non-fatal warning message will be generated if other than 1-hour
averages are specified. This is because the TOXST model currently supports only 1-hour
averages.
The TOXXFILE card may be repeated for each averaging period, but a different filename
should be used for each file since the structure of the output file generated by the TOXXFILE
option does not allow for a clear way to distinguish between results for different averaging
periods. The resulting output file for the AERMOD model is an unformatted file with several
header records identifying the title, averaging period, receptor information, and the threshold
value for that file, followed by records listing every occurrence where the result for any source
group for that averaging period equals or exceeds the threshold value. When one of the source
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groups exceeds the threshold value, the results for all source groups for that averaging period and
receptor location are output. Each concentration that is output through the TOXXFILE option is
paired with an integer ID variable that identifies the averaging period (hour number of the year),
the source group number, and the receptor number corresponding to that value. The
concentration values and corresponding ID variables are stored in buffer arrays, and the arrays are
then written to the unformatted output file when full. The size of the arrays is controlled by the
NPAIR PARAMETER defined in MODULE MAIN1, and is initially set at 100. At the end of the
modeling run, any values remaining in the buffer arrays are written to the file, padded to the right
with zeroes. The structure of the output file generated by the TOXXFILE option is described in
more detail in Section 3.8.2 and in Appendix D. When using the TOXXFILE option, the user will
normally place a single source in each source group. The user should refer to the user's guide for
TOXST for further instructions on the application of the TOXXFILE option of the AERMOD
model.
The following examples illustrate the use of the TOXXFILE option:
OU TOXXFILE 1 l.OE-5 TOXX1HR.BIN
OU TOXXFILE 24 2.5E-3 TOXX24HR.BIN
The Filnam parameter may be up to 40 characters in length. It should be noted that only one
TOXXFILE card may be used for each averaging period. Note: The TOXXFILE option may
produce very large files for runs involving a large number of receptors if a significant percentage
of the results exceed the threshold value.
The RANKFILE keyword outputs values by rank for use in Q-Q (quantile) plots. The
MAXTABLE option must be specified first in order to use the RANKFILE option for a particular
averaging period. However, the RANKFILE output differs from the results in the MAXTABLE
output in that duplicate date/hour occurrences are removed. The syntax and type for the
RANKFILE keyword are summarized below:
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Syntax:
OU RANKFILE Aveper Hinum Filnam (Funit)
Type:
Optional, Repeatable
where the Aveper parameter is the averaging period (e.g., 3_, £, 24 for 3, 8, and 24-hour averages,
or MONTH for monthly averages), and Hinum is the number of high values to be ranked. The
RANKFILE keyword cannot be used with PERIOD averages. As noted above, the MAXTABLE
option must be specified first for the particular Aveper, and the Hinum parameter on the
RANKFILE card must be less than or equal to the Maxnum parameter on the corresponding
MAXTABLE card. Since duplicate dates are removed from the RANKFILE output, the output
file may contain less than the number of requested high values. The NMAX parameter, which
controls the maximum number of values that can be stored, has been set initially to 400. The
Filnam parameter is the name of the file (up to 40 characters) where the RANKFILE results are to
be written. The optional Funit parameter allows the user the option of specifying the Fortran
logical file unit for the output file. The user-specified file unit must be in the range of 26-100,
inclusive. By specifying the same filename and unit for more than one RANKFILE card, results
for different averaging periods may be combined into a single file. If the Funit parameter is
omitted, the model will dynamically allocate a unique file unit for this file according to the
following formula:
IRKUNT= 100 + IAVE
where IRKUNT is the Fortran unit number and IAVE is the averaging period number (the order
of the averaging period as specified on the CO AVERTIME card).
The EVALFILE option is specifically designed for use in generating residuals for model
evaluation studies. The EVALFILE output consists of the arc-maximum normalized
concentration values for each hour of meteorology and for each source specified. The arc
groupings of the receptors must be specified using the RE EVALCART keyword described
above. The syntax and type for the EVALFILE keyword are summarized below:
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Syntax:
OU EVALFILE Srcid Filnam (Funit)
Type:
Optional, Repeatable
where the Srcid parameter is the source ID for which EVALFILE results are requested, the
Filnam parameter is the name of the file (up to 40 characters) where the EVALFILE results are to
be written, and the optional Funit parameter allows the user the option of specifying the Fortran
logical file unit for the output file. The user-specified file unit must be in the range of 26-100,
inclusive. By specifying the same filename and unit for more than one EVALFILE card, results
for different sources may be combined into a single file. If the Funit parameter is omitted, the
model will dynamically allocate a unique file unit for this file according to the following formula:
IELUNT = 400 + ISRC*5
where IELUNT is the Fortran unit number and ISRC is the source number (the order of the source
as specified on the SO pathway).
For each hour of meteorological data processed and for each receptor grouping (e.g., arc),
the EVALFILE option outputs five records containing the source ID, date, arc ID, arc-maximum
normalized concentration (x/Q), emission rate, and other plume dispersion and meteorological
variables associated with the arc-maximum. Since the EVALFILE option looks at receptor
groupings, it must be used in conjunction with the EVALCART keyword described above for the
RE pathway, and a fatal error is generated if no receptor groups are identified.
The SEASONHR option is used to output a file containing the average results by season
and hour-of-day. To select this option, the user must include the SEASONHR keyword on the
OU pathway. The syntax, type, and order for the SEASONHR keyword are summarized below:
Syntax:
OU SEASONHR GroupID Filenam (FUnit)
Optional, Repeatable
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where the GroupID parameter specifies the source group to be output, FileName specifies the
name of the output file, and the optional FileUnit parameter specifies an optional file unit and
must be in the range 26-100, inclusive. If FileUnit is left blank, then the model will dynamically
assign a file unit based on the formula 302+IGRP* 10, where IGRP is the group index number. A
sample from a SEASONHR output file is shown below:
* AERMOD (02222): Example of SEASONHR Output File Option
* MODELING OPTIONS USED:
* CONG WDEP RURAL FLAT TOXICS
* FILE OF SEASON/HOUR VALUES FOR SOURCE GROUP: ALL
* FOR A TOTAL OF 216 RECEPTORS.
* FORMAT: (4(IX,F13.5),IX,F8.2,2X,A8,2X,14,2X,14,2X,14,2X,A8)
* X Y AVERAGE CONG ZELEV GRP NHRS SEAS
0.00000
0.00000
0.18098
2.52520
2.07470
0.93252
0.00000
0.00000
0.15772
2.48554
6.09119
4.49830
0.00000
0.00000
0.10114
2.12970
2.79993
1. 97200
HOUR NET ID
POL1
POL1
POL1
POL1
POL1
POL1
POL1
POL1
POL1
POL1
POL1
POL1
POL1
POL1
POL1
POL1
POL1
POL1
The NHRS column in the output file contains the number of non-calm and non-missing hours
used to calculate the season-by-hour-of-day averages. The SEAS column is the season index, and
is 1 for winter, 2 for spring, 3 for summer and 4 for fall. The records loop through hour-of-day
first, and then through the seasons.
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3.7.3 EVENT Processing Options
EVENT processing in the AERMOD model is designed specifically to perform source
contribution analyses for short term average (less than or equal to 24-hour) events. The events
may either be generated by the AERMOD model, or they may be user-specified events, or both.
Because of this rather narrow focus of applications, the output options are limited to a single
keyword. The EVENTOUT keyword controls the level of detail in the source contribution output
from the EVENT model. The syntax and type of the EVENTOUT keyword are summarized
below:
Syntax:
OU EVENTOUT SOCONT DETAIL
Type:
Mandatory, Non-repeatable
where the SOCONT secondary keyword specifies the option to produce only the source
contribution information in the output file, and the DETAIL secondary keyword specifies the
option to produce more detailed summaries in the output file. The SOCONT option provides the
average concentration (or total deposition) value (i.e., the contribution) from each source for the
period corresponding to the event for the source group. The basic source contribution
information is also provided with the DETAIL option. In addition, the DETAIL option provides
the hourly average concentration (or total deposition) values for each source for every hour in the
averaging period, and a summary of the hourly meteorological data for the event period. In
general, the DETAIL option produces a larger output file than the SOCONT file, especially if
there are a large number of sources. There is no default setting for the EVENTOUT options.
3.8 CONTROLLING INPUT AND OUTPUT FILES
This section describes the various input and output files used by the AERMOD model,
and discusses control of input and output (I/O) on the IBM-compatible PC environment. Much of
this discussion also applies to operating the model in other environments.
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3.8.1 Description of AERMOD Input Files
The two basic types of input files needed to run all of the AERMOD model are the input
runstream file containing the modeling options, source data and receptor data, and the two input
meteorological data files. Each of these is discussed below, as well as a special file that may be
used to initialize the AERMOD model with intermediate results from a previous run.
3.8.1.1 Input Runstream File.
The input runstream file contains the user-specified options for running the various
AERMOD model (called AERMOD.INP), includes the source parameter data and source group
information, defines the receptor locations, specifies the location and parameters regarding the
meteorological data, and specifies the output options. Details regarding the keywords and
parameters used in the input runstream file are provided in Section 3, and Appendix B.
For the PC-executable version of the model available on the SCRAM website, the
runstream file is explicitly opened by the model using a Fortran OPEN statement, and the integer
variable, INUNIT, specifies the unit number for the file. The variable INUNIT is initialized to a
value of 7 in a DATA statement in MODULE MAIN1, and is therefore available to all of the
necessary subroutines.
3.8.1.2 Meteorological Data Files.
The input meteorological data is read into the AERMOD model from two separate data
files, one corresponding to surface (scalar) parameters, and the other corresponding to multi-level
profiles of data. The meteorological data filenames and format are specified within the input
runstream file using the ME SURFFILE and PROFFILE keywords. The AERMOD model
accepts meteorological data that has been preprocessed by the AERMET meteorological
preprocessor program (EPA, 2004b). The data are read from formatted ASCII files of hourly
sequential records.
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The meteorological data files are explicitly opened by the model using Fortran OPEN
statements, and the integer variables MFUNIT for the surface/scalar file and MPUNIT for the
profile file are used to specify the unit numbers for the files. The variable MFUNIT is initialized
to a value of 19 and MPUNIT is initialized to a value of 16 in a DATA statement in MODULE
MAIN1, and are therefore available to all of the necessary subroutines.
3.8.1.3 Initialization File for Model Re-start.
The AERMOD model has an optional capability to store intermediate results to an
unformatted (sometimes called binary) file for later re-starting of the model in the event of a
power failure or user interrupt. This unformatted file may therefore be used as an input file to
initialize the model. This option is controlled by the SAVEFILE (saves intermediate results to a
file) and the INITFILE (initialize result arrays from a previously saved file) keywords on the CO
pathway.
When initializing the model for the re-start option, the user specifies the name of the
unformatted results file on the INITFILE keyword. The default filename used if no parameter is
provided is TMP.FIL. The initialization file is explicitly opened by the AERMOD model, and the
integer variable, IRSUNT, specifies the unit number for the file. The variable IRSUNT is
initialized to a value of 15 in a DATA statement in MODULE MAIN1, and is therefore available
to all of the necessary subroutines.
3.8.2 Description of AERMOD Output Files
The AERMOD model produce a variety of output files, including the main print file of
model results, an unformatted file of intermediate results for later re-start of the model
(AERMOD only), and several output data files for specialized purposes. These files are described
in detail below.
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3.8.2.1 Output Print File.
The AERMOD model produces a main output print file of model results called
AERMOD.OUT. The contents and organization of this file were shown in Figure 2-5. This file
includes an echo of the input runstream images at the beginning of the file (up until a NO ECHO
input is encountered). A summary of runstream setup messages and a summary of the inputs
follow the echo of inputs. The input summary includes a summary of modeling options, source
data, receptor data, and meteorological data, following the same order as the pathways in the
runstream file. If model calculations are performed, then the model results are summarized next.
The content and order of the model result summaries depend on the output options selected and
on the particular model being run. Following the detailed model results are summary tables of the
high values for each averaging period and source group. The final portion of the main output
print file is the summary of messages for the complete model run.
For the PC-executable version of the model available on the SCRAM website, the main
print output file is explicitly opened by the model using a Fortran OPEN statement, and the
integer variable, IOUNIT, specifies the unit number for the file. The variable IOUNIT is
initialized to a value of 8 in a DATA statement in MODULE MAIN1, and is therefore available
to all of the necessary subroutines.
By opening the printed output file explicitly, the outputs are not automatically formatted
for the printer. This formatting is accomplished using the CARRIAGECONTROL specifier in
the OPEN statement for the output file.
3.8.2.2 Detailed Error Message File.
The user may select an option for the model to save a separate file of detailed error and
other messages, through use of the CO ERRORFIL keyword. The format and syntax of these
messages is described in Appendix C. The order of messages within the file is the order in which
they were generated by the model. The file includes all types of messages that were generated.
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The error message file is explicitly opened by the model using a Fortran OPEN statement,
and the integer variable, IERUNT, specifies the unit number for the file. The variable IERUNT is
initialized to a value of 10 in a DATA statement in MODULE MAIN1, and is therefore available
to all of the necessary subroutines.
3.8.2.3 Intermediate Results File for Model Re-start.
The AERMOD model has an optional capability to store intermediate results to an
unformatted (sometimes called binary) file for later re-starting of the model in the event of a
power failure or user interrupt. This unformatted file may therefore be used as an input file to
initialize the model. This option is controlled by the SAVEFILE (saves intermediate results to a
file) and the INITFILE (initialize result arrays from a previously saved file) keywords on the CO
pathway.
When saving the intermediate results for the re-start option, the user specifies the name of
the unformatted results file on the SAVEFILE keyword. The user has the option of specifying a
single filename, two filenames (for alternate saves), or specifying no filename. The default
filename used if no parameter is provided is TMP.FIL. If a single file is used, then the
intermediate results file is overwritten on each successive dump, with the chance that the file will
be lost if the interrupt occurs during the time that the file is opened. If two filenames are provided,
then the model also saves to the second file on alternate dumps, so that the next most recent
dump will always be available. The main save file is explicitly opened by the AERMOD model,
and the integer variable, IDPUNT, specifies the unit number for the file. The variable IDPUNT is
initialized to a value of 12 in a BLOCK DATA subprogram of the model. If a second save file is
used, then it is also opened explicitly, and the integer variable IDPUN2, initialized to a value of
14, specifies the unit number.
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3.8.2.4 Maximum Value/Threshold File.
The user may select an option for the AERMOD model to generate a file or files of concentration
values exceeding a user-specified threshold. The OU MAXIFILE keyword controls this option.
The user may select separate files for each averaging period and source group combination for
which a list of threshold violations may be needed. Each file includes several records with header
information identifying the averaging period, source group and threshold value, and then a record
for every occurrence where the result for that averaging period/source group equals or exceeds
the threshold value. Each of these records includes the averaging period, source group ID, date
for the threshold violation (ending hour of the averaging period), the x, y, z and flagpole receptor
height for the receptor location where the violation occurred, and the concentration value.
The structure of the threshold violation file is described in more detail in Appendix D.
Each of the files selected by the user is opened explicitly by the model as an formatted file. The
filenames are provided on the input runstream image. The user may specify the file unit on the
MAXIFILE card through the optional FUNIT parameter. User-specified units must be greater
than or equal to 26, and are recommended to be less than or equal to 100. If no file unit is
specified, then the file unit is determined internally according to the following formula:
IMXUNT = 100 + IGRP*10 + IAVE
where EVIXUNT is the Fortran unit number, IGRP is the source group number (the order in which
the group is defined in the runstream file), and IAVE is the averaging period number (the order of
the averaging period as specified on the CO AVERTIME card). This formula will not cause any
conflict with other file units used by the model for up to 9 source groups and up to 9 short term
averaging periods.
3.8.2.5 Sequential Results File for Postprocessing.
The user may select an option for the AERMOD model to generate a file or files of
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concentration values suitable for postprocessing. The OU POSTFILE keyword controls this
option. The user may select separate files for each averaging period and source group
combination for which postprocessing may be needed. For each file requested, the user has the
option of specifying whether to use unformatted files suitable for postprocessing or to use a plot
format which could allow for importing the x,y,conc files into a graphics package for plotting.
For the unformatted file option, each file consists of sequential unformatted records of values at
each receptor location for every averaging period calculated. For the plot file format option, each
file consists of formatted records listing the x-coordinate, y-coordinate and concurrent
concentration values for each receptor and for all averaging periods calculated. For certain
applications, these files may become quite large, and should only be used when needed,
especially when using the plot format.
The structure of both types of postprocessing file is described in more detail in Appendix
D. Each of the postprocessing files selected by the user is opened explicitly by the model as
either an unformatted or a formatted file, depending on the option selected. The filenames are
provided on the input runstream image. The user may specify the file unit on the POSTFILE card
through the optional FUNIT parameter. User-specified units must be greater than or equal to 26,
and are recommended to be less than or equal to 100. If no file unit is specified, then the file unit
is determined internally according to the following formulas:
IPSUNT = 200 + IGRP* 10 + IAVE for short term averages
IAPUNT = 300 + IGRP* 10 - 5 for PERIOD averages
where IPSUNT and IAPUNT are the Fortran unit numbers, IGRP is the source group number (the
order in which the group is defined in the runstream file), and IAVE is the averaging period
number (the order of the averaging period as specified on the CO AVERTIME card). This
formula will not cause any conflict with other file units used by the model for up to 9 source
groups and up to 9 short term averaging periods.
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3.8.2.6 High Value Summary File for Plotting.
The user may select an option for the AERMOD model to generate a file or files of the highest
concentration values at each receptor suitable for importing into a graphics package in order to
generate contour plots. The OU PLOTFILE keyword controls this option. The user may select
separate files for each averaging period, source group and high value combination for which a
plot file may be needed. Each file includes several records with header information identifying
the averaging period, source group and high value number of the results, and then a record for
each receptor which contains the x and y coordinates for the receptor location, the appropriate
high value at that location, and the averaging period, source group and high value number.
The structure of the plot file is described in more detail in Appendix D. Each of the plot
files selected by the user is opened explicitly by the model as an formatted file. The filenames are
provided on the input runstream image. The user may specify the file unit on the PLOTFILE card
through the optional FUNIT parameter. User-specified units must be greater than or equal to 26,
and are recommended to be less than or equal to 100. If no file unit is specified, then the file unit
is determined internally according to the following formulas:
IPLUNT = (IVAL+3)* 100 + IGRP* 10 + IAVE for short term averages
IPPUNT = 300 + IGRP* 10 for PERIOD averages
where IPLUNT and IPPUNT are the Fortran unit numbers, IVAL is the high value number (1 for
FIRST highest, 2 for SECOND highest, etc.), IGRP is the source group number (the order in
which the group is defined in the runstream file), and IAVE is the averaging period number (the
order of the averaging period as specified on the CO AVERTIME card). This formula will not
cause any conflict with other file units used by the model for up to 9 source groups and up to 9
short term averaging periods.
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3.8.2.7 TOXX Model Input Files
The user may select an option for the AERMOD model to generate an unformatted file or
files of concentration values exceeding a user-specified threshold for use with the TOXX model
component of TOXST. The OU TOXXFILE keyword controls this option. The user may select
separate files for each averaging period for which a threshold violation file may be needed. Each
file includes several records with header information identifying the title, averaging period,
threshold value, and receptor network information, and then records including every occurrence
where the result of any source group for that averaging period equals or exceeds the threshold
value. Records are also output that identify the averaging period (hour number of the year),
source group number and receptor number corresponding to the concentration values.
The structure of the threshold exceedance file for use with the TOXX model component of
TOXST is described in more detail in Appendix D. Each of the files selected by the user is
opened explicitly by the model as an unformatted file. The filenames are provided on the input
runstream image. The user may specify the file unit on the TOXXFILE card through the optional
Funit parameter. User-specified units must be greater than or equal to 26, and are recommended
to be less than or equal to 100. If no file unit is specified, then the file unit is determined
internally according to the following formula:
ITXUNT = 300 + IAVE
where ITXUNT is the Fortran unit number, and IAVE is the averaging period number (the order
of the averaging period as specified on the CO AVERTIME card). This formula will not cause
any conflict with other file units used by the model for up to 4 short term averaging periods.
The user may also select an option for the AERMOD model to generate an output for use
with the RISK model component of TOXLT. The OU TOXXFILE keyword also controls this
option. The user can specify a separate TOXXFILE for each long term averaging period and
source group combination. The TOXXFILE option may also be used for PERIOD averages with
3-87
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the AERMOD model. The structure of the TOXXFILE output for AERMOD is very similar to
the long term PLOTFILE output, except that results are output for each individual source in the
specified source group. The structure of the long term TOXXFILE is described in more detail in
Appendix D. Each of the files selected by the user is opened explicitly by the model as a
formatted file. The filenames are provided on the input runstream image. The user may specify
the file unit on the TOXXFILE card through the optional Funit parameter. User-specified units
must be greater than or equal to 26, and are recommended to be less than or equal to 100. If no
file unit is specified, then the file unit is determined internally according to the following
formulas:
ITXUNT = 500 + IAVE* 10 + IGRP for long term averages
IPXUNT = 700 + IGRP* 10 for PERIOD averages
where ITXUNT and IPXUNT are the Fortran unit numbers, IAVE is the averaging period number
(in the order of months, seasons or quarters, and annual), and IGRP is the source group number
(in the order is which the groups are defined in the SO pathway). This formula will not cause any
conflict with other file units used by the model for up to 9 source groups.
3.8.3 Control of File Inputs and Outputs (I/O)
3.8.3.1 Control of I/O on PCs.
The main input runstream file and the main output print file are specified internally by
AERMOD as AERMOD.INP and AERMOD.OUT, respectively. Therefore, a standard command
line to execute the AERMOD model might look something like this:
C:\>AERMOD
where the "DOS prompt" has been given as "C:\>", but may look different on different systems,
or may include a subdirectory specification. The output file generated by the DOS version
3-88
-------
includes page feeds that are written directly to the file as part of the header for each page, rather
than using the Fortran carriage control of T. This is accomplished by including a compiler-
specific parameter to set CARRIAGECONTROL = 'Fortran' on the OPEN statement for the
output file.
3.8.3.2 Controlling I/O on Other Computer Systems.
Since the main input runstream file and the main output print file are specified internally
by AERMOD, control of I/O on other computer systems will be the same, with the possible
exception of the compiler-specific option to set CARRIAGECONTROL = 'Fortran' on the OPEN
statement for the output file.
3-89
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4.0 REFERENCES
Environmental Protection Agency, 1995: Industrial Source Complex (ISC3) Dispersion Model
User's Guide - Volumes I and II. EPA-454/B-95-003a and b, U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina 27711.
Environmental Protection Agency, 2004a: AERMOD: Description of Model Formulation. EPA-
454/R-03-004. U.S. Environmental Protection Agency, Research Triangle Park, North
Carolina 27711.
Environmental Protection Agency, 2004b: User's Guide for the AERMOD Meteorological
Preprocessor (AERMET). EPA-454/B-03-002. U.S. Environmental Protection Agency,
Research Triangle Park, North Carolina 27711.
Environmental Protection Agency, 2004c: User's Guide for the AERMOD Terrain Preprocessor
(AERMAP). EPA-454/B-03-003. U.S. Environmental Protection Agency, Research
Triangle Park, North Carolina 27711.
Environmental Protection Agency, 2000: Meteorological Monitoring Guidance for Regulatory
Modeling Applications. EPA-454/R-99-005. U.S. Environmental Protection Agency,
Research Triangle Park, North Carolina 27711.
Schulman, L.L., D.G. Strimaitis, and J.S. Scire, 2000: Development and Evaluation of the
PRIME Plume Rise and Building Downwash Model. Journal of the Air & Waste
Management Association, Vol. 50, pp 378-390.
4-1
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APPENDIX A. ALPHABETICAL KEYWORD REFERENCE
This appendix provides an alphabetical listing of all of the keywords used by the
AERMOD model. Each keyword is identified as to the pathway for which it applies, the keyword
type (either mandatory or optional, and either repeatable or non-repeatable), and with a brief
description of the function of the keyword. For a more complete description of the keywords,
including a list of associated parameters, refer to the Detailed Keyword Reference in Section 3 or
the Functional Keyword/Parameter Reference in Appendix B.
A-l
-------
Keyword
AREAVERT
AVERTIME
BUILDHGT
BUILDWID
DAYRANGE
DAYTABLE
DCAYCOEF
DEBUGOPT
DISCCART
DISCPOLR
ELEVUNIT
EMISFACT
EMISUNIT
Path
SO
CO
SO
SO
ME
OU
CO
CO
RE
RE
SO
RE
SO
SO
Type
M-R
M-N
O-R
O-R
O-R
O-N
O-N
O-N
O-R
O-R
O-N
O-N
O-R
O-N
Keyword Description
Specifies location of vertices for an AREAPOLY source
type (mandatory if AREAPOLY source is used)
Averaging time(s) to process (up to NAVE short term plus
PERIOD or ANNUAL averages)
Building height values for each wind sector
Building width values for each wind sector
Specifies days or ranges of days to process (default is to
process all data read in)
Option to provide summaries for each averaging period for
each day processed.
Optional decay coefficient for exponential decay
Option to generate detailed result and meteorology files for
debugging purposes
Defines the discretely placed receptor locations referenced
to a Cartesian system
Defines the discretely placed receptor locations referenced
to a polar system
Defines input units for receptor elevations (RE path), or
source elevations (SO path) (defaults to meters)
Optional input for variable emission rate factors
Optional conversion factors for emission units and
concentration units
Type: M - Mandatory
O - Optional
N - Non-repeatable
R - Repeatable
A-2
-------
Keyword
ERRORFIL
EVALCART
EVALFILE
EVENTFIL
EVENTLOC
EVENTOUT
EVENTPER
FINISHED
FLAGPOLE
GRIDCART
GRIDPOLR
HALFLIFE
HOUREMIS
INCLUDED
INITFILE
LOCATION
Path
CO
RE
OU
CO
EV
OU
EV
ALL
CO
RE
RE
CO
SO
SO, RE
CO
SO
Type
O-N
O-R
O-R
O-N
M-R
M-N
M-R
M-N
O-N
O-R
O-R
O-N
O-R
O-R
O-N
M-R
Keyword Description
Option to generate detailed error listing file (error file is
mandatory for CO RUNORNOT NOT case)
Defines discretely placed receptor locations referenced to
a Cartesian system, grouped by arc for use with the
EVALFILE output option
Option to output file of normalized arc maxima for model
evaluation studies
Specifies whether to generate an input file for EVENT
model
Describes receptor location for an event
Specifies the level of output information provided by the
EVENT model
Describes data and averaging period for an event
Identifies the end of inputs for a particular pathway
Specifies whether to accept receptor heights above local
terrain (m) for use with flagpole receptors, and allows for
a default flagpole height to be specified
Defines a Cartesian grid receptor network
Defines a polar receptor network
Optional half life used for exponential decay
Option for specifying hourly emission rates in a separate
file
Option to include input data from a separate file in the
runstream for the SO and/or RE pathways
Option to initialize model from file of intermediate
results generated by SAVEFILE option
Identifies coordinates for particular source location
A-3
-------
Keyword
MAXIFILE
MAXTABLE
MODELOPT
MULTYEAR
PLOTFILE
POLLUTID
POSTFILE
PROFBASE
PROFFILE
RANKFILE
Path
OU
ou
CO
CO
ou
CO
ou
ME
ME
OU
Type
O-R
O-R
M-N
O-N
O-R
M-N
O-R
M-N
M-N
O-R
Keyword Description
Option to list events exceeding a threshold value to file
(if CO EVENTFIL option is used, these events are
included in the input file generated for the EVENT
model)
Option to summarize the overall maximum values
Job control and dispersion options
Specifies that run is part of a multi-year run, e.g., for
PM-10 H6H in five years
Option to write certain results to a storage file suitable
for input to plotting routines
Identifies pollutant being modeled
Option to write results to a mass storage file for
postprocessing
Specifies the base elevation (above MSL) for the
potential temperature profile
Describes input profile meteorological data file
Option to produce output file of ranked values for Q-Q
plots
A-4
-------
Keyword
RECTABLE
RUNORNOT
SAVEFILE
SCIMBYHR
SITEDATA
SRCGROUP
SRCPARAM
STARTEND
STARTING
SURFDATA
SURFFILE
TITLEONE
TITLETWO
TOXXFILE
UAIRDATA
WDROTATE
WINDCATS
Path
OU
CO
CO
ME
ME
SO
SO
ME
ALL
ME
ME
CO
CO
OU
ME
ME
ME
Type
O-R
M-N
O-N
O-N
O-N
M-R
M-R
O-N
M-N
M-N
M-N
M-N
O-N
O-R
M-N
O-N
O-N
Keyword Description
Option to output value(s) by receptor
Identifies whether to run model or process setup
information only
Option to store intermediate results for later restart of the
model after user or system interrupt
Specifies sampling parameters for the SCIM option
Describes on-site meteorological station
Identification of source groups
Identifies source parameters for a particular source
Specifies start and end dates to be read from input
meteorological data file (default is to read entire file)
Identifies the start of inputs for a particular pathway
Surface meteorological station
Describes input surface meteorological data file
First line of title for output
Optional second line of output title
Creates output file formatted for use with TOXX model
component of TOXST
Upper air meteorological station
Wind direction rotation adjustment
Upper bound of wind speed categories
A-5
-------
APPENDIX B. FUNCTIONAL KEYWORD/PARAMETER REFERENCE
This appendix provides a functional reference for the keywords and parameters used by
the input runstream files for the AERMOD model. The keywords are organized by functional
pathway, and within each pathway the order of the keywords is based on the function of the
keyword within the model. The pathways used by the model are as follows, in the order in which
they appear in the runstream file and in the tables that follow:
CO - for specifying overall job COntrol options;
SO - for specifying SOurce information;
RE - for specifying REceptor information;
ME - for specifying MEteorology information and options;
EV - for specifying EVent information and options;
OU - for specifying OUtput options.
The pathways and keywords are presented in the same order as in the Detailed Keyword
Reference in Section 3, and in the Quick Reference at the end of the manual.
Two types of tables are provided for each pathway. The first table lists all of the
keywords for that pathway, identifies each keyword as to its type (either mandatory or optional
and either repeatable or non-repeatable), and provides a brief description of the function of the
keyword. The second type of table, which takes up more than one page for most pathways,
presents the parameters for each keyword, in the order in which they should appear in the
runstream file where order is important, and describes each parameter in detail.
The following convention is used for identifying the different types of input parameters.
Parameters corresponding to secondary keywords which should be input "as is" are listed on the
tables with all capital letters and are underlined. Other parameter names are given with an initial
capital letter and are not input "as is." In all cases, the parameter names are intended to be
descriptive of the input variable being represented, and they often correspond to the Fortran
variable names used in the model code. Parentheses around a parameter indicate that the
parameter is optional for that keyword. The default that is taken when an optional parameter is
left blank is explained in the discussion for that parameter.
B-l
-------
TABLE B-l
DESCRIPTION OF CONTROL PATHWAY KEYWORDS
CO Keywords
STARTING
TITLEONE
TITLE TWO
MODE LOP T
AVERT IME
URBANOPT
POLLUTID
HAL EL I FE
DCAYCOEF
FLAGPOLE
RUNORNOT
EVENTFIL2
SAVEFILE3
INITFILE3
MULT YEAR3
DEBUGOPT
ERRORFIL
FINISHED
T
M
M
o
M
M
0
M
0
0
0
M
0
0
0
o
0
0
M
ype
- N
- N
- N
- N
- N
- N
- N
- N1
- N1
- N
- N
- N
- N
- N
- N
- N
- N
- N
Keyword Description
Identifies the start of CONTROL pathway inputs
First line of title for output
Optional second line of title for output
Job control and dispersion options
Averaging time(s) to process
Specifies parameters for urban dispersion option
Identifies type of pollutant being modeled
Optional half life used for exponential decay
Optional decay coefficient
Specifies whether to accept receptor heights above local terrain (m)
for use with flagpole receptors, and allows for default flagpole
height to be specified
Identifies whether to run model or process setup information only
Specifies whether to generate an input file for EVENT model
Option to store intermediate results for later restart of the model
after user or system interrupt
Option to initialize model from file of intermediate results
generated by SAVEFILE option
Option to process multiple years of meteorological data (one year
per run) and accumulate high short term values across years
Option to generate detailed result and meteorology files for
debugging purposes
Option to generate detailed error listing file
Identifies the end of CONTROL pathway inputs
N - Non-Repeatable
R - Repeatable
1) Either HALFLIFE or DCAYCOEF may be specified. If both cards appear a warning message
will be issued and the first value entered will be used in calculations. Default assumes
a half life of 4 hours for S02 modeled in urban mode.
2) The EVENTFIL keyword controls whether or not to generate an input file for EVENT
processing. The primary difference between AERMOD regular processing and EVENT
processing by AERMOD is in the treatment of source group contributions. The AERMOD model
treats the source groups independently, whereas EVENT processing determines individual
source contributions to particular events, such as the design concentrations determined
from AERMOD, or user-specified events. By specifying the EVENTFIL keyword, an input
runstream file will be generated that can be used directly for EVENT processing. The
events included in the generated EVENT processing input file are defined by the RECTABLE
and MAXIFILE keywords on the OU pathway, and are placed in the EVent pathway.
3) The SAVEFILE and INITFILE keywords work together to implement the model's re-start
capabilities. Since the MULTYEAR option utilizes the re-start features in a special way
to accumulate high short term values from year to year, it cannot be used together with
the SAVEFILE or INITFILE keyword in the same model run.
B-2
-------
TABLE B-2
DESCRIPTION OF CONTROL PATHWAY KEYWORDS AND PARAMETERS
Keyword
TITLEONE
where :
TITLE TWO
where :
MODELOPT
where :
AVERT IME
where :
Parameters
Titlel
Titlel
Title2
Title2
First line of title for output, character string of up
to 68 characters
Optional second line of title for output, character
string of up to 68 characters
DFAULT CONG FLAT NOSTD NOCHKD NOWARN SCREEN TOXICS SCIM
DFAULT
CONG
FLAT
NOSTD
NOCHKD
NOWARN
SCREEN
TOXICS
SCIM
Specifies use of regulatory default options (stack tip
downwash, elevated terrain effects), overrides the
presence of FLAT, NOSTD, NOCHKD, and SCREEN keywords
Specifies calculation of concentration values (deposition
algorithm has not been implemented yet)
Option to assume flat terrain
Option to use no stack-tip downwash
Option to by-pass date checking for non-sequential
meteorological data file (for evaluation and screening
purposes only)
Option to suppress printing of warning messages in the
main output file
Option to run AERMOD in a screening mode (makes
centerline calculations, sets NOCHKD option on,
limits averaging period to 1-hour)
Option to use air toxics option (s) : SCIM
Sampled Chronological Input Model; parameters must be
specified on the ME pathway
Timel Time2 Time3 Time4 MONTH PERIOD
TimeN
MONTH
PERIOD
Nth optional averaging time (1^, 2_, 3_, 4_, 6_, 8_, 12,
2A_-hr ; number of periods limited by NAVE parameter)
Option to calculate MONTHly averages (counts toward
NAVE limit)
Option to calculate averages for the entire data
PERIOD
B-3
-------
TABLE B-2 (CONT.)
DESCRIPTION OF CONTROL PATHWAY KEYWORDS AND PARAMETERS
URBANOPT
whe re :
POLLUTID
whe re :
HALFLIFE
whe re :
DCAYCOEF
whe re :
FLAGPOLE
whe re :
Urbpop (Urbname) (UrbRoughness )
UrbPop
UrbName
UrbRoughness
Pollut
Pollut
Haflif
Haflif
Specifies the population of the urban area
Specifies the name of the urban area (optional)
Specifies the urban surface roughness length, meters (optional,
defaults to 1.0m)
Identifies type of pollutant being modeled. Any name
of up to eight characters may be used, e.g., S02,
NOX, CO, PM10, TSP or OTHER. Use of PM10, PM-10 or OTHER
allows for the use of the MULTYEAR option.
Half life used for exponential decay (s)
Decay
Decay
(Flagdf )
Flagdf
Decay coefficient for exponential decay (s"1) = 0.693/HAFLIF
Default value for height of (flagpole) receptors
above local ground level, a default value of 0.0m
is used if this optional parameter is omitted
B-4
-------
TABLE B-2 (CONT.)
DESCRIPTION OF CONTROL PATHWAY KEYWORDS AND PARAMETERS
RUNORNOT
where :
EVENTFIL
where :
SAVEFILE
where :
INITFILE
where :
MULT YEAR
where :
DEBUGOPT
where :
ERRORFIL
where :
RUN or NOT
RUN
NOT
(Evfile) (E-
Evfile
Evopt
Indicates to run full model calculations
Indicates to process setup data and report errors,
but to not run full model calculations
/opt)
Identifies the filename to be used to generate a file
for input to EVENT model (Def ault=EVENTFIL . INP)
Optional parameter to specify the level of output
detail selected for the EVENT model: either
SOCONT or DETAIL (default is DETAIL if this para-
meter is omitted)
(Savfil) (Dayinc) (Savfl2)
Savfil
Dayinc
Savfl2
(Inifil)
Inifil
H6H Savfil
H6H
Savfil
Inifil
Specifies name of disk file to be used for storing
intermediate results (default = TMP.FIL) file is
overwritten after each dump)
Number of days between dumps (optional: default is 1)
Optional second disk filename to be used on alternate
dumps - eliminates risk of system crash during the
dump. If blank, file is overwritten each time.
Specifies name of disk file of intermediate results
to be used for initializing run (default = TMP.FIL)
(Inifil)
Specifies the High-Sixth-High is being calculated for use in
pre-1997 PM10 processing
Specifies name of disk file to be used for storing
results at end of the year
Optional name of disk file used for initializing the
parameter is not used for the first year in the
multi-year run.
MODEL (Dbgfil) and/or METEOR (Dbmfil)
MODEL
(Dbgfil)
METEOR
(Dbmfil)
(Errfil)
Errfil
Specifies that MODEL debugging output will be generated
Optional filename for the model calculation debug file
Specifies that METEORological profile data file will be generated
Optional filename for the meteorological profile data file
Specifies name of detailed error listing file
(default = ERRORS. LSI)
B-5
-------
TABLE B-3
DESCRIPTION OF SOURCE PATHWAY KEYWORDS
SO Keywords
STARTING
ELEVUNIT
LOCATION
SRCPARAM
BUILDHGT
BUILDWID
XBADJ
YBADJ
AREAVERT
URBANSRC
EMI S FACT
EMI SUN IT
HOUREMI S
INCLUDED
SRCGROUP1
FINISHED
T
M
0
M
M
Q
Q
0
0
M
Q
Q
0
0
0
M
M
ype
- N
- N
- R
- R
- R
- R
- R
- R
- R
- R
- R
- N
- R
- R
- R
- N
Keyword Description
Identifies the start of SOURCE pathway inputs
Defines input units for source elevations (defaults to meters), must
be first keyword after SO STARTING if used.
Identifies coordinates for particular source
Identifies source parameters for a particular source
Building height values for each wind sector
Building width values for each wind sector
Along-flow distances from the stack to the center of the upwind face
of the projected building
Across-flow distances from the stack to the center of the upwind face
of the projected building
Specifies location of vertices for an AREAPOLY source type (mandatory
if AREAPOLY source is used)
Identifies which sources to model with urban effects
Optional input for variable emission rate factors
Optional unit conversion factors for emissions, concentrations
Option for specifying hourly emission rates in a separate file
Option to include data from a separate file in the runstream
Identification of source groups
Identifies the end of SOURCE pathway inputs
Source groups are treated independently for AERMOD.
B-6
-------
TABLE B-4
DESCRIPTION OF SOURCE PATHWAY KEYWORDS AND PARAMETERS
Keyword
ELEVUNIT
where :
LOCATION
where :
SRCPARAM
where :
BUILDHGT
where :
BUILDWID
where :
Parameters
METERS or FEET
METERS
FEET
Specifies input units for source elevations of meters
Specifies input units for source elevations of feet
Note: This keyword applies to source elevations only.
Srcid Srctyp Xs Ys (Zs)
Srcid
Srctyp
Xs
Ys
Source identification code (alphanumeric string
of up to eight characters)
Source tvpe : POINT, VOLUME, AREA, AREAPOLY, AREACIRC
x-coord of source location, SW corner for AREA (in m)
y-coord of source location, SW corner for AREA (in m)
Optional z-coord of source location (elevation above
mean sea level, defaults to 0.0 if omitted)
Srcid Ptemis Stkhqt Stktmp Stkvel Stkdia (POINT source)
Vlemi
3 Relhgt Syinit Szinit (VOLUME source)
Aremis Relhgt Xinit (Yinit) (Angle) (Szinit) (AREA source)
Aremis Relhgt Nverts (Szinit) (AREAPOLY source)
Aremis Relhgt Radius (Nverts) (Szinit) (AREACIRC source)
Srcid
Emis
Hgt
Stktmp
Stkvel
Stkdia
Syinit
Szinit
Xinit
Yinit
Angle
Nverts
Radius
Source identification code
Source emission rate: in g/s for Ptemis or Vlemis,
g/(s-m2) for Aremis for concentration
Source physical release height above ground (center
of height for VOLUME)
Stack gas exit temperature (K)
Stack gas exit velocity (m/s)
Stack inside diameter (m)
Initial lateral dimension of VOLUME source (m)
Initial vertical dimension of VOLUME or AREA source (m)
Length of side of AREA source in X-direction (m)
Length of side of AREA source in Y-direction (m) (optional
parameter, assumed to be equal to Xinit if omitted)
Orientation angle of AREA source relative to North (degrees),
measured positive clockwise, rotated around the source location,
(Xs,Ys) (optional parameter, assumed to be 0.0 if omitted)
Number of vertices used for AREAPOLY or AREACIRC source (between 3
and 20, optional for AREACIRC sources)
Radius of circular area for AREACIRC source (m)
Srcid (or Srcrng) Dsbh(i), i=l,36
Srcid
Srcrng
Dsbh
Source identification code
Range of sources (inclusive) for which building
dimensions apply, entered as two alphanumeric
strings separated by a '-'
Array of direction-specific building heights (m)
beginning with 10 degree flow vector and increment-
ing by 10 degrees clockwise
Srcid (or Srcrng) Dsbw(i), i=l,36
Srcid
Srcrng
Dsbw
Source identification code
Range of sources (inclusive) for which building
dimensions apply
Array of direction-specific building widths (m)
beginning with 10 degree flow vector and increment-
ing by 10 degrees clockwise
B-7
-------
TABLE B-4 (CONT.)
DESCRIPTION OF SOURCE PATHWAY KEYWORDS AND PARAMETERS
XBADJ
where :
YBADJ
where :
AREAVERT
where :
URBANSRC
where :
EMI S FACT
where :
EMISUNIT
where :
Srcid (or Srcrng) Xbadj(i), i=l,36
Srcid
Srcrng
Xbadj ( i)
Source identification code
Range of sources (inclusive) for which XBADJ distances apply
Array of direction-specific along-wind distances beginning with
10 degree flow vector and incrementing by 10 degrees clockwise
Srcid (or Srcrng) Ybadj(i), i=l,36
Srcid
Srcrng
Ybadj (i)
Srcid Xv(l)
Srcid
Xv(l)
Yv(l)
Xv(i)
Yv(i)
Source identification code
Range of sources (inclusive) for which YBADJ distances apply
Array of direction-specific across-wind distances beginning with
10 degree flow vector and incrementing by 10 degrees clockwise
Yv(l) Xv(2) Yv(2) ... Xv(i) Yv(i)
Source identification code
X-coordinate of the first vertex of an AREAPOLY source (must be
the same as the value of Xs for that source defined on the SO
LOCATION card)
Y-coordinate of the first vertex of an AREAPOLY source (must be
the same as the value of Ys for that source defined on the SO
LOCATION card)
X-coordinate for the ith vertex of an AREAPOLY source
Y-coordinate for the ith vertex of an AREAPOLY source
Srcid' s and/or Srcrng' s
Srcid
Srcrng
Specifies which source (s) will be modeled with urban effects
Specifies a range of sources that will be modeled with urban
effects
Srcid (or Srcrng) Qflag Qfact(i), i=l,n
Srcid
Srcrng
Qflag
Qfact
Source identification code
Range of sources (inclusive) for which emission rate factors
apply
Variable emission rate flag:
SEASON for seasona; MONTH for monthly; HROFDY for hour-of-day;
WSPEED for wind speed category; SEASHR for season-by-hour;
SHRDOW for season by hour-of-day by day-of-week (M-F, Sat, Sun) ;
and SHRDOW7 for season by hour-of-day by day-of-week (M, Tu,W,
Th, F, Sat, Sun)
Array of scalar emission rate factors, for:
SEASON, n=4; MONTH, n=12; HROFDY, n=24;
WSPEED, n=6; SEASHR, n=96; SHRDOW, n=288;
SHRDOW7, n=672
Emifac Emilbl Conlbl
Emif ac
Emilbl
Conlbl
Emission rate factor used to adjust units of output
(default value is 1.0 E06 for CONG for grams to micrograms)
Label to use for emission units (default is grams/sec)
Label to use for concentrations (default is micrograms /m3)
B-8
-------
TABLE B-4 (CONT.)
DESCRIPTION OF SOURCE PATHWAY KEYWORDS AND PARAMETERS
HOUREMI S
where :
INCLUDED
where :
SRCGROUP
where :
Emifil Srcid's Srcrng's
Emif il
Srcid' s
Srcrng ' s
Specifies name of the hourly emission rate file
Discrete source IDs that are included in the hourly emission
file
Source ID ranges that are included in the hourly emission
file
Incfil
Incfil
Specifies name of the file to be included in the runstream
data
Grpid Srcid's Srcrng's
Grpid
Srcid' s
Srcrng ' s
Group ID (Grpid = ALL specifies group including all
sources), number of source groups limited by NGRP
parameter in the computer code
Discrete source IDs to be included in group
Source ID ranges to be included in group
Note: Card may be repeated with same Grpid if
more space is needed to specify sources
B-9
-------
TABLE B-5
DESCRIPTION OF RECEPTOR PATHWAY KEYWORDS
RE Keywords
STARTING
ELEVUNIT
GRIDCART
GRIDPOLR
DISCCART
DISCPOLR
EVALCART
INCLUDED
FINISHED
Type
M
0
o
o
o
0
0
o
M
- N
- N
- R1
- R1
- R1
- R1
- R1
- R
- N
Keyword Description
Identifies the start of RECEPTOR pathway inputs
Defines input units for receptor elevations (defaults to meters),
must be first keyword after RE STARTING if used.
Defines a Cartesian grid receptor network
Defines a polar receptor network
Defines the discretely placed receptor locations referenced to a
Cartesian system
Defines the discretely placed receptor locations referenced to a
polar system
Defines discrete Cartesian receptor locations for use with
EVALFILE output option
Option to include data from a separate file in the runstream
Identifies the end of RECEPTOR pathway inputs
At least one of the following must be present: GRIDCART, GRIDPOLR, DISCCART,
DISCPOLR, or EVALCART. Multiple receptor networks can be specified in a single run,
including both Cartesian and polar, up to an overall maximum controlled by the NREC
parameter.
B-10
-------
TABLE B-6
DESCRIPTION OF RECEPTOR PATHWAY KEYWORDS AND PARAMETERS
Keyword
ELEVUNIT
where :
GRIDCART
where :
Parameters
METERS or FEET
METERS
FEET
Netid STA
XYINC
or XPNTS
YPNTS
ELEV
HILL
FLAG
Specifies input units for receptor elevations of
meters
Specifies input units for receptor elevations of feet
Note: This keyword applies to receptor elevations
only.
Xinit Xnum Xdelta Yinit Ynum Ydelta
Gridxl Gridx2 Gridx3 .... GridxN, and
Gridyl Gridy2 Gridy3 .... GridyN
Row Zelevl Zelev2 Zelev3 . . . ZelevN
Row Zhilll Zhill2 ZhillS . . . ZhillN
Row Zflaql Zflaq2 Zflaq3 . . . ZflaqN
END
Netid
STA
XYINC
Xinit
Xnum
Xdelta
Yinit
Ynum
Ydelta
XPNTS
Gridxl
GridxN
YPNTS
Gridyl
GridyN
ELEV
Row
Zelev
HILL
Row
Zhill
FLAG
Row
Zflag
END
Receptor network identification code (up to eiqht
alphanumeric characters)
Indicates STArt of GRIDCART subpathway, repeat for
each new Netid
Keyword identifyinq qrid network qenerated from
x and y increments
Startinq x-axis qrid location in meters
Number of x-axis receptors
Spacinq in meters between x-axis receptors
Startinq y-axis qrid location in meters
Number of y-axis receptors
Spacinq in meters between y-axis receptors
Keyword identifyinq qrid network defined by a series
of x and y coordinates
Value of first x-coordinate for Cartesian qrid
Value of 'nth' x-coordinate for Cartesian qrid
Keyword identifyinq qrid network defined by a series
of x and y coordinates
Value of first y-coordinate for Cartesian qrid
Value of 'nth' y-coordinate for Cartesian qrid
Keyword to specify that receptor elevations follow
Indicates which row (y-coordinate fixed) is beinq
input
An array of receptor terrain elevations for
a particular Row
Keyword to specify that hill heiqht scales follow
Indicates which row (y-coordinate fixed) is beinq
input
An array of receptor hill heiqht scales for
a particular Row
Keyword to specify that flaqpole receptor heiqhts
follow
Indicates which row (y-coordinate fixed) is beinq
input
An array of receptor heiqhts above local terrain
elevation for a particular Row (flaqpole receptors)
Indicates END of GRIDCART subpathway, repeat for each
new Netid
B-ll
-------
TABLE B-6 (CONT.)
DESCRIPTION OF RECEPTOR PATHWAY KEYWORDS AND PARAMETERS
GRIDPOLR
where :
Netid STA
ORIG
or ORIG
DIST
DDIR
or GDIR
ELEV
HILL
FLAG
END
Netid
STA
ORIG
Xinit
Yinit
Srcid
DIST
Ringl
RingN
DDIR
Dirl
DirN
GDIR
Dirnum
Dirini
Dirinc
ELEV
Dir
Zelev
HILL
Dir
Zhill
FLAG
Dir
Zflag
END
Xinit Yinit,
Srcid
Ringl Ring2 Ring3 . . . RingN
Dirl Dir2 Dir3 . . . DirN,
Dirnum Dirini Dirinc
Dir Zelevl Zelev2 Zelev3 . . . ZelevN
Dir Zhilll Zhill2 ZhillS . . . ZhillN
Dir Zflagl Zflag2 Zflag3 . . . ZflagN
Receptor network identification code (up to eight
alphanumeric characters)
Indicates STArt of GRIDPOLR subpathway, repeat for
each new Netid
Optional keyword to specify the origin of the polar
network (assumed to be at x=0, y=0 if omitted)
x-coordinate for origin of polar network
y-coordinate for origin of polar network
Source ID of source used as origin of polar network
Keyword to specify distances for the polar network
Distance to the first ring of polar coordinates
Distance to the 'nth' ring of polar coordinates
Keyword to specify discrete direction radials for the
polar network
First direction radial in degrees (1 to 360)
The 'nth' direction radial in degrees (1 to 360)
Keyword to specify generated direction radials for
the polar network
Number of directions used to define the polar system
Starting direction of the polar system
Increment (in degrees) for defining directions
Keyword to specify that receptor elevations follow
Indicates which direction is being input
An array of receptor terrain elevations for a
particular direction radial
Keyword to specify that hill height scales follow
Indicates which direction is being input
An array of receptor hill height scales for a
particular direction radial
Keyword to specify that flagpole receptor heights
follow
Indicates which direction is being input
An array of receptor heights above local terrain
elevation for a particular direction (flagpole
receptors )
Indicates END of GRIDPOLR subpathway, repeat for each
new Netid
B-12
-------
TABLE B-6 (CONT.)
DESCRIPTION OF RECEPTOR PATHWAY KEYWORDS AND PARAMETERS
DISCCART
where :
DISCPOLR
where :
EVALCART
where :
INCLUDED
where :
Xcoord Ycoord (Zelev Zhill) (Zflag)
Xcoord
Ycoord
Zelev
Zhill
Zflag
Srcid Dist
Srcid
Dist
Direct
Zelev
Zhill
Zflag
x-coordinate for discrete receptor location
y-coordinate for discrete receptor location
Elevation above sea level for discrete receptor
location (optional), used only for ELEV terrain
Hill height scale corresponding with a discrete
receptor location (optional), used only for ELEV terrain
Receptor height (flagpole) above local terrain
(optional), used only with FLAGPOLE keyword
Direct (Zelev Zhill) (Zflag)
Specifies source identification for which discrete
polar receptor locations apply (used to define the
origin for the discrete polar receptor)
Downwind distance to receptor location
Direction to receptor location, in degrees clockwise
from North
Elevation above sea level for receptor location
(optional), used only for ELEV terrain
Hill height scale corresponding with a discrete
receptor location (optional), used only for ELEV terrain
Receptor height (flagpole) above local terrain
(optional), used only with FLAGPOLE keyword
Xcoord Ycoord Zelev Zhill Zflag Arcid (Name)
Xcoord
Ycoord
Zelev
Zhill
Zflag
Arcid
(Name)
x-coordinate for discrete receptor location
y-coordinate for discrete receptor location
Elevation above sea level for discrete receptor
location (optional) , used only for ELEV terrain
Hill height scale corresponding with a discrete
receptor location (optional), used only for ELEV terrain
Receptor height (flagpole) above local terrain
(optional), used only with FLAGPOLE keyword
Receptor arc ID used to group receptors along
an arc or other grouping (up to eight characters)
Optional name for receptor (up to eight characters)
Incfil
Incfil
Specifies name of the file to be included in the runstream data
B-13
-------
TABLE B-7
DESCRIPTION OF METEOROLOGY PATHWAY KEYWORDS
ME Keywords
STARTING
Identifies the start of METEOROLOGY pathway inputs
SURFFILE
Describes input meteorological surface data file
PROFFILE
SURFDATA
UAIRDATA
SITEDATA
PROFBASE
Specifies the base elevation for the potential temperature profile
3TARTEND
Specifies start and end dates to be read from input meteorological
data file (default is to read entire file)
DAYRANGE
Specifies days or ranges of days to process (default is to process
all data read in)
3CIMBYHR
Specifies the parameters for the SCIM (Sampled Chronological Input
Model) option (see CO MODELOPT)
WDROTATE
WINDCATS
FINISHED
Identifies the end of METEOROLOGY pathway inputs
B-14
-------
TABLE B-8
DESCRIPTION OF METEOROLOGY PATHWAY KEYWORDS AND PARAMETERS
Keyword
SURFFILE
where :
PROFFILE
where :
SURFDATA
where :
UAIRDATA
where :
SITEDATA
where :
PROFBASE
where :
STARTEND
where :
Parameters
Sfcfil (Format)
Sfcfil
Format
Specify filename for surface meteorological input file
Specify format for input file
Profil (Format)
Profil
Format
Stanum Year
Stanum
Year
Name
Xcoord
Ycoord
Stanum Year
Stanum
Year
Name
Xcoord
Ycoord
Stanum Year
Stanum
Year
Name
Xcoord
Ycoord
Specify filename for profile meteorological input file
Specify format for input file
(Name) (Xcoord Ycoord)
Station number, e.g. 5-digit WBAN number for NWS
surface station
Year of data being processed (four digits)
Station name (optional)
x-coordinate of station location (m) (optional)
y-coordinate of station location (m) (optional)
(Name) (Xcoord Ycoord)
Station number, e.g. 5-digit WBAN number for NWS
upper air station
Year of data being processed (four digits)
Station name (optional)
x-coordinate of station location (m) (optional)
y-coordinate of station location (m) (optional)
(Name) (Xcoord Ycoord)
Station number for on-site meteorological data
station
Year of data being processed (four digits)
Station name (optional)
x-coordinate of station location (m) (optional)
y-coordinate of station location (m) (optional)
BaseElev (Units)
BaseElev
Units
Base elevation (above MSL) for the potential temperature profile
Units of BaseElev: METERS or FEET (default is METERS)
Strtyr Strtmn Strtdy (Strthr) Endyr Endmn Enddy (Endhr)
Strtyr
Strtmn
Strtdy
Strthr
Endyr
Endmn
Enddy
Endhr
Year of first record to be read
Month of first record to be read
Day of first record to be read
Hour of first record to be read (optional)
Year of last record to be read
Month of last record to be read
Day of last record to be read
Hour of last record to be read (optional)
Note: File read begins with hour 1 of the start
date and ends with hour 24 of the end date
if Stahr and Endhr are omitted.
B-15
-------
TABLE B-8 (CONT.)
DESCRIPTION OF METEOROLOGY PATHWAY KEYWORDS AND PARAMETERS
DAY RANGE
where :
SCIMBYHR
where :
WDROTATE
where :
WINDCATS
where :
Rangel Range2 Range3 . . . RangeN
Range 1
RangeN
First range of days to process, either as individual
day (XXX) or as range (XXX-YYY) ; days may be input
as Julian dates (XXX) or as month and day (XX/YY)
The 'nth' range of days to process
NRegStart NReglnt NWetStart NWetlnt (SfcFilnam PflFilnam)
NRegStart
Nreglnt
NWetStart
NWetlnt
SfcFilnam
PflFilnam
Specifies the first hour to be sampled with the SCIM option;
required to have a value from 1 to 24
Specifies the sampling interval, in hours
Specifies the first wet hour to be sampled with the SCIM option
(not currently used in AERMOD, should set to 0)
Specifies the wet sampling interval, in hours (not currently
used in AERMOD, should be set to 0)
Optional output file name to list the surface meteorological
data for the sampled hours
Optional output file name to list the profile meteorological
data for the sampled hours
Rotang
Rotang
Specifies angle (in degrees) to rotate wind direction
measurements to correct for alignment problems;
value of Rotang is subtracted from WD measurements,
i.e., rotation is counterclockwise
Wsl Ws2 Ws3 Ws4 Ws5
Wsl
Ws2
Ws3
Ws4
Ws5
Upper bound of first wind speed category (m/s)
Upper bound of second wind speed category (m/s)
Upper bound of third wind speed category (m/s)
Upper bound of fourth wind speed category (m/s)
Upper bound of fifth wind speed category (m/s)
(sixth category is assumed to have no upper bound)
B-16
-------
TABLE B-9
DESCRIPTION OF EVENT PATHWAY KEYWORDS
EV Keywords
STARTING
EVENTPER
EVENTLOC
FINISHED
Type
M - N
M - R
M - R
M - N
Keyword Description
Identifies the start of EVENT pathway inputs
Describes data and averaging period for an event
Describes receptor location for an event
Identifies the end of EVENT pathway inputs
B-17
-------
TABLE B-10
DESCRIPTION OF EVENT PATHWAY KEYWORDS AND PARAMETERS
Keyword
EVENTPER
where:
EVENTLOC
where:
Parameters
Evname Aveper Grpid Date
Name
Grpid
Aveper
Date
Specify name of event to be processed (e.g. H2H24ALL) ,
(up to eight alphanumeric characters)
Specify source group ID for event
Specify averaging period for event
Specify data period for event (ending YYMMDDHH for
averaging period)
Evname XR= Xr YR= Yr (Zelev) (Zflag)
or
RNG= Rncr DIR= Dir (Zelev) (Zflag)
Evname
XR=
YR=
RNG=
DIR=
Zelev
Zflag
Specify name of event to be processed (e.g. H2H24ALL) ,
(up to eight alphanumeric characters)
X-coordinate for event (discrete Cartesian receptor)
Y-coordinate for event (discrete Cartesian receptor)
Distance range for event (discrete polar receptor)
Radial direction for event (discrete polar receptor)
Terrain elevation for event (optional)
Receptor height above ground for event (optional)
EVENT locations can be input as either discrete Cartesian receptors (XR=, YR=)
or as discrete polar receptors (RNG=, DIR=). Events that are specified in the
file generated by the AERMOD model (CO EVENTFIL card) are always given as
discrete Cartesian coordinates. Discrete polar receptors are assumed to be
relative to an origin of (0,0).
B-18
-------
TABLE B-11
DESCRIPTION OF OUTPUT PATHWAY KEYWORDS
OU Keywords
STARTING
RECTABLE
MAXTABLE
DAY TABLE
MAXIFILE
POSTFILE1
PLOTFILE1
TOXXFILE
RANKFILE
EVALFILE
EVENTOUT
FINISHED
Type
M -
0 -
0 -
0 -
0 -
0 -
0 -
0 -
0 -
0 -
M -
M -
N
R
R
N
R
R
R
R
R
R
N
N
Keyword Description
Identifies the start of OUTPUT pathway inputs
Option to specify value (s) by receptor for output
Option to summarize the overall maximum values
Option to print summaries for each averaging period for each day
processed.
Option to list events exceeding a threshold value to file (if CO
EVENTFIL option is used, these events are included in the input
file generated for the EVENT model) .
Option to write results to a mass storage file for postprocessing.
Option to write certain results to a storage file suitable for
input to plotting routines
Option to write results to a storage file suitable for input to the
TOXX model component of TOXST or the RISK
Option to output file of ranked values for Q-Q plots (must be used
with the MAXTABLE keyword)
Option to output file of normalized arc maxima from EVALCART
receptors for model evaluation studies
Specifies the level of output information provided for EVENT
processing
Identifies the end of OUTPUT pathway inputs
POSTFILE is used to output concurrent concentration values for particular source
groups and averaging times across the receptor network, suitable for postprocessing,
such as might be done for implementing the intermediate terrain policy. PLOTFILE is
used to output specific design values, such as second high concentrations, across
the receptor network, suitable for plotting concentration contours.
B-19
-------
TABLE B-12
DESCRIPTION OF OUTPUT PATHWAY KEYWORDS AND PARAMETERS
Keyword
RECTABLE
where :
MAXTABLE
where :
DAY TABLE
where :
Parameters
Aveper FIRST SECOND . . . SIXTH or
Aveper 1ST 2ND . . . 6TH
Aveper
FIRST
SECOND
SIXTH
1ST
2ND
6TH
Averaging period to summarize with high values
(keyword ALLAVE specifies all averaging periods)
Select summaries of FIRST highest values by receptor
Select summaries of SECOND highest values by receptor
Select summaries of SIXTH highest values by receptor
Select summaries of 1ST highest values by receptor
Select summaries of 2ND highest values by receptor
Select summaries of 6TH highest values by receptor
Note: If two keywords are input separated by a
dash (e.g. FIRST-THIRD) , then summaries of
all high values in that range are provided.
The number of high values allowed is con-
trolled by the NVAL parameter in the computer
code (initially set at 3) . Also, if the
CO EVENTFIL keyword is exercised, then the
events generated by the RECTABLE keyword are
included in the input file for EVENT model.
Aveper Maxnum
Aveper
Maxnum
Averaging period to summarize with maximum values
(keyword ALLAVE specifies all averaging periods)
Specifies number of overall maximum values to
summarize (number of maximum values permitted is
limited by the NMAX parameter in the computer code,
initially set at 50)
Avperl Avper2 Avper3 . . .
Avperl
Averaging period to summarize with values by receptor
for each day of data processed (keyword ALLAVE for
first parameter specifies all averaging periods)
Averaging period to summarize with maximum values
(keyword AL LAVE specifies all averaging periods)
Specifies number of overall maximum values to
summarize (number of maximum values permitted is
limited by the NMAX parameter in the computer code,
initially set at 50)
B-20
-------
TABLE B-12(CONT.)
DESCRIPTION OF OUTPUT PATHWAY KEYWORDS AND PARAMETERS
MAXIFILE
where :
POSTFILE
where :
PLOTFILE
where :
TOXXFILE
where :
RANKFILE
where :
EVALFILE
where :
EVENTOUT
where :
Aveper Grpid Thresh Filnam (Funit)
Aveper
Grpid
Thresh
Filnam
Funit
Specifies averaging period for list of values equal to
or exceeding a threshold value
Specifies source group to be output to file
Threshold value (e.g. NAAQS) for list of exceedances
Name of disk file to store maximum values
Optional parameter to specify the file unit
Note: If the CO EVENTFIL keyword is exercised, then the
events generated by the MAXIFILE keyword are included
in the input file for EVENT processing.
Aveper Grpid Format Filnam (Funit)
Aveper
Grpid
Format
Filnam
Funit
Specifies averaging period to be output to file,
e.g., 24 for 24-hr averages, PERIOD for period averages
Specifies source group to be output to file
Specifies format of file, either UNFORM for
unformatted files or PLOT for formatted files for plotting
Specifies filename for output file
Optional parameter to specify the file unit
Aveper Grpid Hivalu Filnam (Funit) (Short Term values)
Aveper Grpid Filnam (Funit) (PERIOD or ANNUAL averages)
Aveper
Grpid
Hivalu
Filnam
Funit
Specifies averaging period to be output to file, e.g., 24 for
24-hr averages,
PERIOD for period averages, WINTER for winter averages, etc.
Specifies source group to be output to file
Specifies high value summary (e.g. FIRST, SECOND, 1ST, 2ND, etc.)
to be output to file (must be selected on a RECTABLE card)
Specifies filename for output file
Optional parameter to specify the file unit
Aveper Cutoff Filnam (Funit)
Aveper
Cutoff
Filnam
Funit
Specifies averaging period to be output to file,
e.g., ]__ for 1-hr averages.
Specifies cutoff (threshold) value in g/m3 for outputting
results for AERMOD model
Specifies filename for output file
Optional parameter to specify the file unit
Aveper Hinum Filnam (Funit)
Aveper
Hinum
Filnam
Funit
Specifies averaging period to be output to file,
e.g., 24 for 24-hr averages
Specifies the number of high values to be ranked
Specifies filename for output file
Optional parameter to specify the file unit
Srcid Filnam (Funit)
Srcid
Filnam
Funit
Specifies the source ID to be output to file
Specifies filename for output file
Optional parameter to specify the file unit
SOCONT or DETAIL
SOCONT
DETAIL
Provide source contribution information only in the event output
Include hourly concentrations for each source and hourly
meteorological data in the event output
B-21
-------
APPENDIX C. EXPLANATION OF ERROR MESSAGE CODES
C.I INTRODUCTION
The AERMOD input runstream is checked to identify parameters that are missing or
potentially in error, and the input source and meteorological data are checked and flagged for
possible erroneous values.
The AERMOD model uses a "defensive programming" approach to eliminate as much
as possible of the user's work in debugging the input runstream file. Also, a great deal of effort
has been made to eliminate the possibility of run time errors, such as "divide by zero," and to
point out questionable input data. Error messages are reported to the user in two ways. A
summary of messages is provided in the main output result file, and the user can also request a
detailed message listing file.
Message Summary: Whether the user selects a detailed error listing file or not, the
AERMOD model output a summary of messages within the output result file. This message
table gives the number of messages of each type, together with a detailed list of all the fatal
errors and warning messages. During setup processing, if no errors or warnings are generated,
then the model simply reports to the user that "SETUP Finishes Successfully."
Detailed Message Listing File: The AERMOD model provide the option of saving a
detailed list of all messages generated by the model in a separate output file. The user can
select this option by specifying the keyword "ERRORFIL" followed by a filename inside the
COntrol pathway. For example, the following statements will save all the error messages to an
ASCII text file named "errormsg.out":
CO STARTING
ERRORFIL errormsg.out
CO FINISHED
C-l
-------
C.2 THE OUTPUT MESSAGE SUMMARY
There are two message summaries provided in the standard output file of the
AERMOD model. The first one is located after the echo of input runstream file images and
before the input data summary. This summary will take one of two forms, depending on
whether any fatal error or non-fatal warning messages were generated, and also depending on
whether the option to RUN or NOT to run was selected on the CO RUNORNOT card. If there
are no errors or warnings generated during the setup processing, and the RUN option was
selected, then the model simply reports that "SETUP Finishes Successfully." If any fatal
errors or warning messages were generated during the setup processing, or if the option NOT
to run was selected, then a more detailed summary is provided. This summary provides a
message count for each type of message, and a detailed listing of each fatal error and warning
message generated. The second message summary table is located at the very end of the
standard output result file, and it sums up the messages generated by the complete model run -
both setup processing and run-time processing.
An example of a setup processing message summary is shown in Figure C-l.
C-2
-------
A Total of
A Total of
A Total of
******** FATAL ERROR MESSAGES ********
* * * NONE * * *
WARNING MESSAGES
* * * NONE * * *
FIGURE C-l. EXAMPLE OF AN AERMOD MESSAGE SUMMARY
C.3 DESCRIPTION OF THE MESSAGE LAYOUT
Three types of messages can be produced by the model during the processing of input
runstream images and during model calculations. These are described briefly below:
Errors that will halt any further processing, except to identify additional error
conditions (type E);
• Warnings that do not halt processing but indicate possible errors or suspect
conditions (type W); and
• Informational messages that may be of interest to the user but have no direct
bearing on the validity of the results (type I).
The messages have a consistent structure which contains the pathway ID, indicating
which pathway the messages are generated from; the message type followed by a three-digit
message number; the line number of the input runstream image file for setup messages (or the
meteorology hour number for runtime messages); the name of the module (e.g. the subroutine
name) from which the message is generated; a detailed message corresponding to the message
code; and an 8-character simple hint to help the user spot the possible source of the problem.
C-3
-------
The following is an example of a detailed message generated from the CO pathway:
CO E100 8 EXPATH: Invalid Pathway Specified. The Troubled Pathway is FF
The message syntax is explained in more detail below (values in parentheses give the column
numbers within the message line for each element):
PW Txxx LLLL mmittmittm: MESSAGE Hints
Hints to help you determine the
nature of errors (keyword, pathway
where the error occurs, ... etc.)
(73:80)
Detailed message for this code (22:71)
Name of the code module from which the
message is generated (14:19)
The line number of the input runstrearn
image file where the message occurs; If
message occurs in runtime operation, the
hour number of the meteorology file is
given (9:12)
Numeric message code (a 3-digit number) (5:7)
Message type (E, W, I) (4:4)
Pathway ID (CO, SO, RE, ME, EV, or OU) (1:2) or
MX for meteorological data extraction, or CN
for calculation messages
If an error occurs during processing of an included file (either SO INCLUDED or RE
INCLUDED), the line number will represent the line number of the included file. The line
number of the runstream file is saved before processing the included data, and then restored
when processing returns to the main runstream file.
C-4
-------
The three message types are identified with the letters E (for errors), W (for warnings),
and I (for informational messages). The 3-digit message codes are grouped into general
categories corresponding to the different stages of the processing. Theses categories are:
100 - 199 Input Runstream Image Structure Processing
200 - 299 Parameter Setup Processing
300-399 Data and Quality Assurance Processing
400 - 499 Run Time Message Processing
500-599 Input/Output Message Processing
A detailed description of each of the message codes currently used in the model is provided in
the next section.
C.4 DETAILED DESCRIPTION OF THE ERROR/MESSAGE CODES
INPUT RUNSTREAM IMAGE STRUCTURE PROCESSING, 100-199
This type of message indicates problems with the basic syntax and/or structure of the
input runstream image. Typical messages include errors like "Missing mandatory keyword",
"Illegal Keyword", ..., etc. If a fatal error of this kind is detected in a runstream image, a fatal
error message is written to the message file and any attempt to process data is prohibited,
although the remainder of the runstream file is examined for other possible errors. If a
warning occurs, data may still be processed, although the inputs should be checked carefully to
be sure that the condition causing the warning does not indicate an error.
100 Invalid Pathway Specified. The pathway ID should be a 2 character string. It should
be one of the following: CO for control pathway, SO for source pathway, RE for
receptor pathway (or EV for event pathway for EVENT processing), ME for
meteorology data setting pathway, and OU for output format pathway. Its position is
normally confined to columns 1 and 2 (1:2) of the input runstream file. However, the
model does allow for a shift of the entire input runstream file of up to 3 columns. If the
inputs are shifted, then all input records must be shifted by the same amount. The
invalid pathway is repeated at the end of the message.
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105 Invalid Keyword Specified. The keyword ID should be an 8-character string. Its
position is normally confined to columns 4 to 11 (4:11) of the input runstream file.
However, the model does allow for a shift of the entire input runstream file of up to 3
columns. If the inputs are shifted, then all input records must be shifted by the same
amount. There should be a space between keyword ID and any other data fields. For a
list of valid keywords, refer to Appendix A or Appendix B. The invalid keyword is
repeated at the end of the message.
110 Keyword is Not Valid for This Pathway. The input keyword is a valid 8-character
string, but it is not valid for the particular pathway. Refer to Appendix A, Appendix B
or Section 3 for the correct usage of the keyword. The invalid keyword is repeated at
the end of the message.
115 Starting and Finishing Statements do not match. Only One STARTING and one
FINISHED statement,respectively, is allowed at the very beginning and the very end of
each pathway block. Check the position and frequency to make sure the input
runstream file meets the format requirement. The pathway during which the error
occurs is included at the end of the message.
120 Pathway is Out of Sequence. The pathways are not input in the correct order. The
correct order is CO, SO, RE, ME, and OU for the AERMOD and AERMOD model,
and CO, SO, ME, EV, and OU for EVENT processing. The offending pathway is
given as a hint.
125 Missing FINISHED Statement - Runstream file is incomplete. One or more FINISHED
statements are missing. A 5-digit status variable is given as a hint. Each digit
corresponds to a pathway in the appropriate order, and is a T if the pathway is
complete and a '0' if the FINISHED is missing. For example, a status of'10111'
indicates that the SO pathway was missing a FINISHED statement. Normally such an
error will generate additional messages as well.
130 Missing Mandatory Keyword. To run the model, certain mandatory keywords must
present in the input runstream file. For a list of mandatory keywords, see Appendix A
or Appendix B. For more detailed information on keyword setup, see the description
of message code 105. The missing keyword is included with the message.
135 Duplicate Non-repeatable Keyword Encountered. More than one instance of a
non-repeatable keyword is encountered. For a list of non-repeatable keywords, see
Appendix A or Appendix B. The repeated keyword is included with the message.
140 Invalid Placement of Keyword. A keyword has been placed out of the acceptable
order, or a STARTING or FINISHED keyword has been placed in an INCLUDED file.
The order for most keywords is not critical, but the relative order of a few keywords is
important for the proper interpretation of the input data. The keyword reference in
Section 3 identifies any requirements for the order of keywords. The keyword that was
improperly placed is included with the message.
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145 Conflicting Options: MULTYEAR and Re-Start Option. The multiple year option for
processing PM-10 values makes use of the re-start routines in the model with some
slight changes to handle the period averages from year to year. As a result, the
MULTYEAR keyword cannot be specified with either the SAVEFILE or INITFILE
keywords.
150 Conflicting Options: MULTYEAR for Wrong Pollutant. The multiple year option is
provided specifically for the processing of PM-10 values to obtain the "high-sixth-high
in five years" design value. Its treatment of the high short term values for multiple year
periods is not consistent with existing air quality standards for other pollutants. To use
the MULTYEAR option, the user must specify a pollutant type (on the CO POLLUTID
card) of PM-10, PM10, or OTHER.
152 ELEVUNIT card must be first for this pathway. The ELEVUNIT card must be the first
non-commented card after STARTING when used on the SO or RE pathway. This
requirement is made in order to simplify reviewing runstream files to determine the
elevation units used for sources and receptors.
154 Conflicting Options: SCIM option cannot be used with the specified option, causing a
fatal error.
155 Conflicting Decay Keyword. The AERMOD model allows for the user to specify the
rate of exponential decay either in terms of the half-life (HALFLIFE keyword) or the
decay coefficient (DCAYCOEF keyword). If both keywords are specified, then only
the first one will be used, and inputs for the second one will be ignored.
156 Option ignored - not valid with SCIM. The specified option is not valid with the SCIM
option and is ignored. This is not a fatal error.
157 Wet SCIM option is not operational yet and the input is ignored. Since the model does
not include wet deposition algorithms yet, the wet SCIM option is not operational.
158 Wet SCIM option is not operational yet and the input is ignored. Since the model does
not include wet deposition algorithms yet, the wet SCIM option is not operational.
160 Duplicate ORIG Secondary Keyword for GRIDPOLR. Only one origin card may be
specified for each grid of polar receptors. The network ID for the effected grid is
included with the message.
170 Invalid Secondary Key for Receptor GRID. The network ID for the effected grid is
included with this message. Refer to Appendix B for the correct syntax of secondary
keywords.
175 Missing Secondary Keyword END for Receptor Grid. The END secondary keyword is
required for each grid of receptors input by the user (keywords GRIDCART and
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GRIDPOLR). It signals the end of inputs and triggers the processing of data for that
particular network.
180 Conflicting Secondary Keyword for Receptor Grid. Two incompatible secondary
keywords have been input for the same grid of receptors, e.g. GDIR and DDIR for the
keyword GRIDPOLR, where GDIR specifies to generate directions with uniform
spacing, and DDIR specifies that discrete, non-uniform directions are being specified.
185 Missing Receptor Keywords. No Receptors Specified. Since none of the RE pathway
keywords are mandatory, a separate error check is made to determine if any of the RE
keywords are specified. At least one of the following keywords must be present:
GRIDCART, GRIDPOLR, DISCCART, DISCPOLR, or EVALCART.
190 No Keywords for OU Pathway and No PERIOD or ANNUAL Averages. All of the
OU pathway keywords are optional, and in fact the model will run if no keywords are
specified on the OU pathway as long as PERIOD or ANNUAL averages are being
calculated. However, if there are no OU keywords and no PERIOD or ANNUAL
averages, then there will be no output generated by the model, and this fatal error
message will be generated.
195 Incompatible Option Used With SAVEFILE or INITFILE. Either a non-fatal message
to warn the user that DAYTABLE results will be overwritten if the model run is
re-started, or a fatal error message generated if the TOXXFILE option is selected with
either the SAVEFILE or INITFILE options.
197 Post-1997 PM10 processing option without the MAXIFILE option is incompatible with
the EVENTFIL option. Threshold violations generated through the MAXIFILE option
are the only events that are compatible with post-1997 PM10 processing for EVENT
processing.
198 The non-default TOXICS option is required in order to use the specified option, such as
the SCIM option.
PARAMETER SETUP PROCESSING, 200-299
This type of message indicates problems with processing of the parameter fields for the
runstream images. Some messages are specific to certain keywords, while others indicate
general problems, such as an invalid numeric data field. If a fatal error of this kind is detected
in a runstream image, a fatal error message is written to the message file and any attempt to
process data is prohibited, although the remainder of the runstream file is examined for other
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possible errors. If a warning occurs, data may still be processed, although the inputs should be
checked carefully to be sure that the condition causing the warning does not indicate an error.
200 Missing Parameter(s). No options were selected for the indicated keyword. Check
Appendix B for the list of parameters for the keyword in question.
201 Not Enough Parameters Specified For The Keyword. Check if there are any missing
parameters following the indicated keyword. See Appendix B for the required
keyword parameters.
202 Too Many Parameters Specified For The Keyword. Refer to Appendix B or Section 3
for the list of acceptable parameters.
203 Invalid Parameter Specified. The inputs for a particular parameter are not valid for
some reason. Refer to Appendix B or Section 3. The invalid parameter is included
with the message.
204 Option Parameters Conflict. Forced by Default to: Some parameters under the
indicated keyword conflict with the other model parameters setting. Refer to Appendix
B or Section 3 for the correct parameter usage. The default setting is specified with the
message.
205 No Option Parameter Setting. Forced by Default to: No setting was specified for a
particular parameter. Refer to Appendix B or Section 3 for the correct parameter
usage. The default setting is specified with the message.
206 Regulatory DFAULT Specified With Non-default Option. The DFAULT option on the
CO MODELOPT card always overrides the specified non-default option, and a
warning message is generated.
207 No Parameters Specified. Default Values Used For. The keyword for which no
parameters are specified is included with the message. Refer to Appendix B or Section
3 for a discussion of the default condition.
208 Illegal Numerical Field Encountered. The model may have encountered a
non-numerical character for a numerical input, or the numerical value may exceed the
limit on the size of the exponent, which could potentially cause an underflow or an
overflow error.
209 Negative Value Appears For A Non-negative Variable. The effected variable name is
provided with the message.
210 Number of Short Term Averages Exceeds Maximum. The user has specified more
short term averages on the CO AVERTIME card than the model array limits allow.
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This array limit is dynamically allocated at model runtime based on model inputs, and
is stored in the NAVE variable. While the model still performs this test, this message
should never occur.
211 Duplicate Parameter(s) Specified for Keyword. A duplicate parameter or set of
parameters has been specified for the indicated keyword. For example, if more than
one POSTFILE keyword is included for the same averaging period and source group,
then this error message will be generated.
212 END Encountered Without (X,Y) Points Properly Set. This error occurs during setting
up the grid of receptors for a Cartesian Network. This message may occur for example
if X-coordinate points have been specified without any Y-coordinate points for a
particular network ID.
213 ELEV Inputs Inconsistent With Option: Input Ignored. This happens when the user
inputs elevated terrain heights for receptors when the FLAT option is specified. The
input terrain heights are ignored and the model proceeds with FLAT terrain modeling.
214 ELEV Inputs Inconsistent With Option: Defaults Used. This happens when the user
does not input elevated terrain heights for receptors when the default option of
incorporating elevated terrain effects is used. The model assumes that the missing
terrain heights are at 0.0 meters for those receptors and proceeds with ELEV terrain
modeling.
215 FLAG Inputs Inconsistent With Option: Input Ignored. This happens when the user
inputs receptor heights above ground for flagpole receptors when the FLAGPOLE
keyword option has not been specified. The input flagpole heights are ignored in the
model calculations.
216 FLAG Inputs Inconsistent With Option: Defaults Used. This happens when the user
does not input receptor heights above ground for flagpole receptors when the
FLAGPOLE keyword option has been specified. The model assumes that the missing
flagpole heights are equal to the default value specified on the CO FLAGPOLE card.
If no default height is specified on the FLAGPOLE card, then a default of 0.0 meters is
assumed.
217 More Than One Delimiter In A Field. For example, 12//34 is an illegal input data item
for the DAYRANGE card, and STACK1--STACK-20 is an illegal specification for a
range of sources.
218 Number of (X, Y) Points Not Match With Number Of ELEV Or FLAG. Check the
number of elevated terrain heights or flagpole receptor heights for the gridded network
associated with the indicated line number in the runstream file.
219 Number Of Receptors Specified Exceeds Maximum. The user has specified more
receptors on the RE pathway than the model array limits allow. This array limit is
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dynamically allocated at model runtime based on model inputs, and is stored in the
NREC variable. While the model still performs this test, this message should never
occur.
220 Missing Origin (Use Default = 0,0) In GRIDPOLR. This is a non-fatal warning
message to indicate that the ORIG secondary keyword has not been specified for a
particular grid of polar receptors. The model will assume a default origin of (X=0,
Y=0).
221 Missing Distance Setting In Polar Network. No distances have been provided
(secondary keyword DIST) for the specified grid of polar receptors.
222 Missing Degree Or Distance Setting In Polar Network. Missing a secondary keyword
for the specified grid of polar receptors.
223 Missing Distance or Degree Field. No data fields have been specified for the indicated
secondary keyword.
224 Number of Receptor Networks Exceeds Maximum. The user has specified more
receptor networks of gridded receptors on the RE pathway than the model array limits
allow. This array limit is dynamically allocated at model runtime based on model
inputs, and is stored in the NNET variable. While the model still performs this test,
this message should never occur.
225 Number of X-Coords Specified Exceeds Maximum. The user has specified more
X-coordinate values for a particular grid of receptors than the model array limits allow.
This array limit is dynamically allocated at model runtime based on model inputs, and
is stored in the IXM variable. While the model still performs this test, this message
should never occur.
226 Number of Y-Coords Specified Exceeds Maximum. The user has specified more
Y-coordinate values for a particular grid of receptors than the model array limits allow.
This array limit is dynamically allocated at model runtime based on model inputs, and
is stored in the IYM variable. While the model still performs this test, this message
should never occur.
227 No Receptors Were Defined on the RE Pathway. Either through lack of inputs or
through errors on the inputs, no receptors have been defined.
228 Default(s) Used for Missing Parameters on Keyword. Either an elevated terrain height
or a flagpole receptor height or both are missing for a discrete receptor location.
Default value(s) will be used for the missing parameter(s).
229 Too Many Parameters - Inputs Ignored on Keyword. Either an elevated terrain height
or a flagpole receptor height or both are provided when the corresponding option has
not been specified. The unneeded inputs are ignored.
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231 Too Many Numerical Values Specified. Too many values have been specified for the
type of input indicated.
232 Number Of Specified Sources Exceeds Maximum. The user has specified more
sources than the model array limits allow. This array limit is dynamically allocated at
model runtime based on model inputs, and is stored in the NSRC variable. While the
model still performs this test, this message should never occur.
233 Building Dimensions Specified for a Non-POINT Source. Building dimensions can
only be specified for a POINT source, since the VOLUME and AREA source
algorithms do not include building downwash.
234 Too Many Sectors Input. For example, the user may have input too many building
heights or widths for a particular source.
235 Number of Source Groups Specified Exceeds Maximum. The user has specified more
source groups than the model array limits allow. This array limit is dynamically
allocated at model runtime based on model inputs, and is stored in the NGRP variable.
While the model still performs this test, this message should never occur.
236 Not Enough BUILDHGTs Specified for a Source ID. There should be 36 building
heights.
237 Not Enough BUILDWIDs Specified for a Source ID. There should be 36 building
widths.
239 Not Enough QFACTs Specified for a Source ID. The number of variable emission rate
factors specified for a particular source is less than the model expects based on the
variable emission rate flag. Check the EMISFACT keyword on the SO pathway in
Appendix B of Section 3 for the appropriate number.
241 Not Enough BUILDLENs Specified for a Source ID. There should be 36 building
lengths specified.
246 Not Enough XBADJs Specified for a Source ID. There should be 36 along-flow
distances from the stack to the center of the upwind face of building specified.
247 Not Enough YBADJs Specified for a Source ID. There should be 36 across-flow
distances from the stack to the center of the upwind face of building specified.
248 No Sources Were Defined on the SO Pathway. There must be at least one LOCATION
card and one SRCPARAM card to define at least one source on the SO pathway.
Either no cards were input or there were errors on the inputs.
250 Duplicate XPNT/DIST or YPNT/DIR Specified for GRID. One of the grid inputs,
either an X-coordinate, Y-coordinate, polar distance range or polar direction, has been
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specified more than once for the same grid of receptors. This generates a non-fatal
warning message.
252 Duplicate Receptor Network ID Specified. A network ID for a grid of receptors
(GRIDCART or GRIDPOLR keyword) has been used for more that one network.
254 Number of Receptor Arcs Exceeds Maximum. This array limit is dynamically
allocated at model runtime based on model inputs, and is stored in the NARC variable.
While the model still performs this test, this message should never occur.
256 EVALFILE Option Used Without EVALCART Receptors. The EVALFILE output
option provides model results designed for model evaluation purposes based on
receptors grouped by arc. Such receptors must be identified using the EVALCART
keyword. If EVALFILE is selected without any EVALCART receptors, this fatal error
message will be generated.
260 Number of Emission Factors Exceeds Maximum. The user has selected an option for
variable emission rate factors that exceeds the array storage limit for emission rate
factors. This array limit is dynamically allocated at model runtime based on model
inputs, and is stored in the NQF variable. While the model still performs this test, this
message should never occur.
262 First Vertex Does Not Match LOCATION for AREAPOLY Source. The coordinates
of the first vertex defined for an AREAPOLY source must match the source location
coordinates provided on the SO LOCATION card.
264 Too Many Vertices Specified for an AREAPOLY Source. The number of vertices
specified on the AREA VERT cards must match the number given on the SRCPARAM
card for that source.
265 Not Enough Vertices Specified for an AREAPOLY Source. The number of vertices
specified on the AREA VERT cards must match the number given on the SRCPARAM
card for that source.
270 Number of High Values Specified Exceeds Maximum. The user has selected a high
short term value on the OU RECTABLE card that exceeds the array storage limit for
high values by receptor. This array limit is dynamically allocated at model runtime
based on model inputs, and is stored in the NVAL variable. While the model still
performs this test, this message should never occur.
280 Number of Maximum Values Specified Exceeds Maximum. The user has selected a
value for the number of overall maximum values on the OU MAXTABLE card that
exceeds the array storage limit for overall maximum values. This array limit is
dynamically allocated at model runtime based on model inputs, and is stored in the
NMAX variable. While the model still performs this test, this message should never
occur.
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294 PERIOD and ANNUAL averages are both selected on the AVERTIME card. The user
can only specify one long-term averaging option, either PERIOD or ANNUAL
average.
295 Invalid Averaging Period Specified for the SCREEN Mode. The SCREEN mode of
AERMOD can only be used with 1-hour averages.
298 Error Allocating Storage for Setup Arrays. An error occurred while allocating storage
for the setup arrays, indicating that there is insufficient memory available on the
computer for the model to run. Try closing other applications and/or reducing the size
of the run. An estimate of memory requirements is provided on the first page of the
output file.
299 Error Allocating Storage for Result Arrays. An error occurred while allocating storage
for the result arrays, indicating that there is insufficient memory available on the
computer for the model to run. Try closing other applications and/or reducing the size
of the run. An estimate of memory requirements is provided on the first page of the
output file.
SETUP DATA AND QUALITY ASSURANCE PROCESSING, 300-399
This type of message indicates problems with the actual values of the parameter data
on the input runstream image. The basic structure and syntax of the input card is correct, but
one or more of the inputs is invalid or suspicious. These messages include quality assurance
checks on various model inputs. Typical messages will tell the consistency of parameters and
data for the setup and run of the model. If a fatal error of this kind is detected in a runstream
image, a fatal error message is written to the message file and any attempt to process data is
prohibited. If a warning occurs, data may or may not be processed, depending on the
processing requirements specified within the run stream input data.
300 Specified Source ID Has Not Been Defined Yet. The message indicates that the user
attempts to use a source ID on a keyword before defining this source ID on a SO
LOCATION card. It could indicate an error in specifying the source ID, an omission
of a LOCATION card, or an error in the order of inputs.
310 Attempt to Define Duplicate LOCATION Card for Source. There can be only one
LOCATION card for each source ID specified. The source ID is included with the
message.
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313 Attempt to Define Duplicate EVENTPER Card for the specified EVENT. There can be
only one EVENTPER card for each EVENT specified. The EVENT name is included
with the message.
315 Attempt to Define Duplicate SRCPARAM Card for Source. There can be only one
SRCPARAM card for each source ID specified. The source ID is included with the
message.
319 No Sources Included in the Specified Source Group. This is a non-fatal warning
message indicating that a source group has been defined that does not include any
sources. The source group ID is provided.
320 Source Parameter May Be Out-of-Range for Parameter. The value of one of the source
parameters may be either too large or too small. The name of the parameter is provided
with the message. Use the line number provided to locate the card in question.
325 Negative Exit Velocity (Set=l .OE-5) for Source ID. The exit velocity for the specified
source ID was input as a negative value. Since the model currently cannot handle
sources with downward momentum, the exit velocity is set to a very small value
(l.OE-5 m/s) and modeling proceeds. This non-fatal message is generated to warn the
user that the input may be in error.
330 Mass Fraction Parameters Do Not Sum to 1. (within +/- 2 percent) for a particular
source.
332 Mass Fraction Parameter Out-of-Range for a particular source. Must be between 0.0
and 1.0, inclusive.
334 Particle Density Out-of-Range for a particular source. Must be greater than 0.0.
340 Possible error in the PROFBASE input. The value input as the base elevation (above
MSL) for the potential temperature file is less than zero.
342 Source ID Mismatch in the Hourly Emissions File. The source ID read from the hourly
emissions file does not match what is expected based on the SO HOUREMIS card. A
source ID and/or date may be out of order or missing in the hourly emissions file. The
source ID read from the file is provided with the error message.
344 Hourly Emission Rate is Zero. The emission rate read from the hourly emission file is
zero for the specified date. This is written as an informational message, and does not
halt processing of the data.
350 Julian Day Out Of Range. This error occurs if the Julian Day selected is less than zero
or greater than 366. Check ME setup to ensure the Julian Day selection.
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352 Missing Field on MULTYEAR Card for Pre-1997 PM10. When using the
MULTYEAR card for pre-1997 PM10 processing, the keyword 'H6H' must be
specified.
353 MULTYEAR Card for PM10 Processing Applies Only for Pre-1997 Applications. Use
High-Fourth-High for Post-1997 PM10 Processing.
354 High-Fourth-High Only Required for Post-1997 PM10 Processing with the
RECTABLE Card.
360 2-digit Year Specified. Valid for the range 1950-2049. Four-digit years are valid for
the entire range of Gregorian dates, but two digit years are accepted.
363 24-Hr and ANNUAL Averages Only are Allowed for Post-1997 PM10 Processing on
the AVERTIME Card.
365 Year Input is Greater than 2147. A four-digit year greater than 2147 has been input to
the model, which will cause an integer overflow.
370 Invalid Date: 2/29 In a Non-leap Year. The year has been identified as a non-leap year,
and a date of 2/29 (February 29) has been specified on the DAYRANGE card. Check
the year and/or the date specification.
380 This Input Variable is Out-of-Range. The indicated value may be too large or too
small. Use the line number to locate the card in question, and check the variable for a
possible error.
381 Latitude in the Surface File is Not Valid. The latitude is read from the header record of
the surface/scalar meteorological data file. If the value is not within the valid range of
0 to 90 degrees, then this error message is generated.
382 Error Decoding Latitude in the Surface File. The latitude is read from the header
record of the surface/scalar meteorological data file. An error occurred trying to
decode the latitude indicating a potential problem with the surface file.
385 Averaging period does not equal 1-hour averages for the TOXXFILE option for the
AERMOD model. The AERMOD model will generate TOXXFILE outputs for other
averaging periods, but the TOXX model component of TOXST currently supports only
the 1-hour averages. This is a non-fatal warning message.
390 Averaging period specified on the EVENTPER card for EVENT processing must be
less than or equal to 24.
391 Aspect ratio (length/width) of an area source is greater than 10. The area source
algorithm in the AERMOD model allows for specifying area sources as elongated
rectangles, however, if the aspect ratio exceeds 10 a warning message will be printed
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out. The user should subdivide the area so that each subarea has an aspect ratio of less
than 10.
392 Error Decoding Latitude. The latitude is read from the header record of the
surface/scalar meteorological data file. The value of the latitude should be followed by
an 'N or an 'S' for the northern or southern hemispheres. If the value cannot be
decoded properly, then this error message is generate.
395 Met. Data Error; Incompatible Version of AERMET. Based on the version date given
in the header record of the surface meteorological data file, the meteorological data
were generated by an older, incompatible version of AERMET.
396 Met. Data Generated by Older Version of AERMET. Based on the version date given
in the header record of the surface meteorological data file, the meteorological data
were generated by an older version of AERMET. The data may be compatible with the
current version of AERMOD, but should be updated with the current version of
AERMET.
RUNTIME MESSAGE PROCESSING, 400-499
This type of message is generated during the model run. Setup processing has been
completed successfully, and the message is generated during the performance of model
calculations. Typical messages will tell the information and error during the model run. If a
fatal error of this kind is detected during model execution, a fatal error message is written to
the message file and any further processing of the data is prohibited. The rest of the
meteorological data file will be read and quality assurance checked to identify additional
errors. If a warning occurs, data may or may not be processed, depending on the processing
requirements specified within the run stream input data.
405 The Value of PHEE Exceeds 1.0. If the value of PHEE, the fraction of the plume
material below Hcrit, is greater than 1.0, then this informational message is generated.
The value of PHEE is then set to 1.0 for the specified date.
406 Increase NVMAX for complex AREAPOLY source. The number of vertices for an
AREAPOLY source exceeds the value of NVMAX, initially set to 20.
410 Flow Vector Out-of-Range. The flow vector must be between 0 and 360 degrees,
inclusive. The date of occurrence is provided with the message (in the form of year,
month, day, hour as YYMMDDHH)
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413 Number of Threshold Violation Events > 9999 for the Specified Averaging Period.
This will result in duplicate event names being written to the EVENTFIL file. The
duplicate events will have to be segregated before running the model in the EVENT
processing mode.
420 Wind Speed Out-of-Range. The wind speed value may be either too large or too small.
An error is generated if the speed is less than 0.0, and a warning is generated if the
speed is greater than 30.0 m/s. The date of occurrence is provided with the message (in
the form of year, month, day, hour as YYMMDDHH).
430 Ambient Temperature Data Out-of-Range. The ambient temperature value may be
either too large or too small. A warning is generated if the temperature is less than
220.0 K or greater than 330 K. The date of occurrence is provided with the message
(in the form of year, month, day, hour as YYMMDDHH).
432 Surface Friction Velocity Out-of-Range. The surface friction velocity may by too
large. A warning is generated if the surface friction velocity is greater than 1.5 m/s.
The date of occurrence is provided with the message (in the form of year, month, day,
hour as YYMMDDHH).
435 Surface Roughness Length Out-of-Range. A warning is generated if the surface
friction velocity is less than 0.001 meters, and the value is set to 0.001 meters to avoid
a divide by zero. The date of occurrence is provided with the message (in the form of
year, month, day, hour as YYMMDDHH).
438 Convective Velocity Scale Out-of-Range. The convective velocity scale may by too
large. A warning is generated if the convective velocity scale is greater than 3.0 m/s.
The date of occurrence is provided with the message (in the form of year, month, day,
hour as YYMMDDHH).
440 Calm Hour Identified in Meteorology Data File. This message is generated if a calm
hour is identified, and provides the date of occurrence (in the form of year, month, day,
hour as YYMMDDHH). A calm hour is identified by a reference wind speed of 0.0
m/s in the surface meteorological data file.
450 Error in Meteorology File - Record Out of Sequence. There is an error in the sequence
of the hourly meteorological data file. The message also provides the date of
occurrence (in the form of year, month, day, hour as YYMMDDHH).
455 Date/Time Mismatch on Hourly Emission File. There is mismatch in the date/time
field between the meteorological data file and the hourly emission file. The message
also provides the date of the occurrence from the surface/scalar file (in the form of
year, month, day, hour as YYMMDDHH).
456 Date/Time Mismatch on Scalar and Profile Data. There is mismatch in the date/time
field between the surface/scalar and the profile meteorological data files. The message
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also provides the date of the occurrence from the surface/scalar file (in the form of
year, month, day, hour as YYMMDDHH).
460 Missing Hour Identified in Meteorology Data File. At least one of the meteorological
variables is missing or invalid for the hour specified (in the form of year, month, day,
hour as YYMMDDHH). If the missing data processing option is not used, then this
message will be generated and any further calculations with the data will be aborted.
The model will continue to read through the meteorological data file and check the
data.
465 Number of Profile Levels Exceeds the Maximum. The profile meteorological data file
includes more than the maximum number of levels, specified by the MXPLVL
PARAMETER in MODULE MAIN1. The value of MXPLVL is provided with the
message.
470 Mixing Height Value is Less Than or Equal to 0.0. This is an informational message
that may indicate an error in the meteorological data file. The message includes the
hour of occurrence (in the form of year, month, day, hour as YYMMDDHH).
475 The Reference Height is Higher than 100 m. The reference height is read from the
surface/scalar meteorological data file. This warning message is generated if the
reference height is higher than 100 meters. Since data for the reference height are used
in surface layer similarity profiles, the reference height should be within the surface
layer (between about 7 and 100 times the surface roughness length).
480 Less Than 1 Year Found for ANNUAL Averages. The input meteorological data file
consists of less than a full year of data. The ANNUAL average requires that a full year
of data or multiple years be available.
485 Data Remaining After End of Year. The ANNUAL average requires full years of input
data (not necessarily calendar years), and there are data remaining after the end of the
year. The number of hours remaining is specified.
487 User-specified Start Date on STARTEND card is Earlier Than Start Date of Data File
with the ANNUAL average or post-1997 PM10 processing option.
INPUT/OUTPUT MESSAGE PROCESSING, 500-599
This type of message is generated during the model input and output. Typical messages
will tell the type of I/O operation (e.g., opening, reading or writing to a file), and the type of
file. If a fatal error of this kind is detected in a runstream image, a fatal error message is
written to the message file and any attempt to process data is prohibited. If a warning occurs,
C-19
-------
data may or may not be processed, depending on the processing requirements specified within
the run stream input data.
500 Fatal Error Occurs During Opening of the Data File. The file specified can not be
opened properly. This may be the runstream file itself, the meteorological data file, or
one of the special purpose output files. This may happen when the file called is not in
the specified path, or an illegal filename is specified. If no errors are found in the
filename specification, then this message may also indicate that there is not enough
memory available to run the program, since opening a file causes a buffer to be opened
which takes up additional memory in RAM. For the special purpose output files, the
hint field includes character string identifying the type of file and the file unit number,
e.g., 'PLTFL312'.
510 Fatal Error Occurs During Reading of the File. File is missing, incorrect file type, or
illegal data field encountered. Check the indicated file for possible problems. As with
error number 500, this message may also indicate that there is not enough memory
available to run the program if no other source of the problem can be identified.
520 Fatal Error Occurs During Writing to the File. Similar to message 510, except that it
occurs during a write operation.
530 CAUTION! Met. Station ID Mismatch with SURFFILE for SURFDATA,
UAIRDATA or SITED ATA. The surface, upper air, or optional on-site station ID
numbers specified on the ME pathway do not agree with the values on the first record
of the surface meteorological data file. This is a non-fatal warning message, but the
input data should be checked carefully to ensure that the correct data file has been used.
540 No RECTABLE/MAXTABLE/DAYTABLE for Averaging Period. No printed output
options selected for a particular averaging period. This is a non-fatal warning
condition for the AERMOD model.
550 File Unit/Name Conflict for the Output Option. This error indicates that a problem
exists with the filename and file unit specification for one of the special purpose output
files. The associated keyword is provided as a hint. The same filename may have been
used for more than one file unit, or vice versa.
560 User Specified File Unit Less Than or Equal to 25 for OU Keyword. A file unit of less
than or equal to 25 has been specified for the indicated special purpose output files.
This is a fatal error condition. File units of less than or equal to 25 are reserved for
system files. Specify a unit number in the range of 26 to 100.
565 Possible conflict With Dynamically Allocated FUNIT. A file unit specified for the
indicated special purpose output files is in the range > 100, and may therefore conflict
C-20
-------
with file units dynamically allocated for special purpose files by the model. This is
typically a non-fatal warning condition.
570 Problem Reading Temporary Event File for Event. The AERMOD model stores high
value events in a temporary file that is used to create the input file for EVENT
processing, if requested, and also to store the high values for the summary tables at the
end of the printed output file. A problem has been encountered reading this file,
possibly because the concentration value was too large and overflowed the fixed format
field of F14.5.
580 End-of-File Reached Trying to Read a Data File. The AERMOD model has
encountered an end-of-file trying the read the indicated file. This may appear when
trying to "re-start" a model run with the CO INITFILE card if there is an error with the
initialization file. Check the data file for the correct filename.
C-21
-------
APPENDIX D. DESCRIPTION OF FILE FORMATS
D.I AERMET METEOROLOGICAL DATA
Two files are produced for input to the AERMOD dispersion model by the AERMET
meteorological preprocessor. The surface OUTPUT contains observed and calculated surface
variables, one record per hour. The PROFILE file contains the observations made at each level of
an on-site tower, or the one level observations taken from NWS data, one record per level per
hour. The contents and format of each of these files is described below:
SURFACE OUTPUT
Header record:
READ( ) latitude, longitude, UA identifier, SF identifier, OS identifier, Version
FORMAT (2(2X,A8),8X,' UA_ID: ',A8,' SF_ID: ',A8,' OS_ID: ',A8,
5X,'VERSION: ',15)
where latitude = latitude specified in Stage 3 of AERMET
longitude = longitude specified in Stage 3 of AERMET
UA identifier = station identifier for upper air data; usually the WBAN
number used to extract the data from an archive data set
SF identifier = station identifier for hourly surface observations; usually the
WBAN number used in extracting the data
OS identifier = on-site identifier
Version = version date of AERMET used to generate file
Data records:
READ( ) year, month, day, j day, hour, H, u*, w*, VPTG, Zlc, Zim, L, z0, B0, r, Ws, Wd, zref
temp, ztemp
FORMAT (3(I2,1X), 13,IX, I2,1X, F6.1,1X, 2(F6.3,1X), F5.0,1X, F8.1,1X, F5.2,1X,
2(F6.2,1X), F7.2,1X, F5.0, 3(1X,F6.1))
where j day = Julian date
D-l
-------
H = sensible heat flux (W/m2)
M* = surface friction velocity (m/s)
w*. = convective velocity scale (m/s)
VPTG = vertical potential temperature gradient in the 500 m layer above
PEL
Zic = height of convectively-generated boundary layer (m)
Zim = height of mechanically-generated boundary layer (m)
L = Monin-Obukhov length (m)
z0 = surface roughness length (m)
B0 = Bowen ratio
r = Albedo
Ws = wind speed (m/s)
Wd = wind direction (degrees)
zref = reference height for Ws and Wd (m)
temp = temperature (K)
ztemp = reference height for temp (m)
The sensible heat flux, Bowen ratio and albedo are not used by AERMOD, but are passed through
by AERMET for information purposes only.
PROFILE
READ( ) year, month, day, hour, height, top, WDnn, WSnn, TTnn, SAnn, SWnn
FORMAT (4(12,IX), F6.1,1X, II,IX, F5.0,1X, F7.2,1X, F7.1, 1X,F6.1, 1X,F7.2)
where height = measurement height (m)
top = 1, if this is the last (highest) level for this hour, or 0 otherwise
WDnn = wind direction at the current level (degrees)
WSnn = wind speed at the current level (m/s)
TTww = temperature at the current level (°C)
SAnn = oe (degrees)
SWww = ow (m/s)
D-2
-------
D.2 THRESHOLD VIOLATION FILES (MAXIFILE OPTION)
The OU MAXIFILE card for the AERMOD model allows the user the option to generate a
file or files of threshold violations for specific source group and averaging period combinations.
The file consists of several header records, each identified with an asterisk (*) in column one.
The header information includes the model name and version number, the first line of the title
information for the run, the list of modeling option keywords applicable to the results, the
averaging period and source group included in the file, and the threshold value. Any value equal
to or exceeding the threshold value will be included in the file. The header also includes the
format used for writing the data records, and column headers for the variables included in the file.
The variables provided on each data record include the averaging period, the source group ID, the
date (YYMMDDHH) for the end of averaging period, the X and Y coordinates of the receptor
location, receptor terrain elevation, hill height scale, flagpole receptor height, and the
concentration value that violated the threshold. The following example from a threshold file
identifies the contents of the MAXIFILE:
AERMOD (02222): A Simple Example Problem for
MODELING OPTIONS USED:
CONG FLAT
MAXI-FILE FOR 3-HR VALUES >= A THRES
the AERMOD Model with
HOLD OF 50.00
PRIME
FOR SOURCE GROUP: ALL
FORMAT: (IX, 13,
AVE GRP DATE
3 ALL 88030112
3 ALL 88030112
3 ALL 88030112
IX, A8,
x
344 .
492.
164 .
IX, 18
68271
40387
44621
8,2 (1X,F13
Y
-60.77
-86.82
-59.85
.5),
3 (IX,
F7.2
ZELEV
686
408
352
0.
0.
0.
00
00
00
,1X,F13
ZHILL
0. 00
0. 00
0. 00
5)
ZFLAG
0
0
0
00
00
00
AVERAGE
67 .
68.
114 .
CONG
83944
92943
30801
D.3 POSTPROCESSOR FILES (POSTFILE OPTION)
The OU POSTFILE card for the AERMOD model allows the user the option of creating
output files of concurrent concentration values suitable for postprocessing. The model offers two
options for the type of file generated - one is an unformatted file, and the other is a formatted file
of X, Y, CONC values suitable for inputting to plotting programs.
D-3
-------
The unformatted POSTFILE option generates a separate unformatted data record of
concurrent values for each averaging period and source group specified. The averaging period
and source group combinations may be written to separate files, or combined into a single file.
Each record begins with the date variable for the end of the averaging period (an integer variable
of the form YYMMDDHH), the averaging period (e.g., an integer value of 3 for 3-hour averages),
and the source group ID (eight characters). Following these three header variables, the record
includes the concentration values for each receptor location, in the order in which the receptors
are defined on the RE pathway. The results are output to the unformatted file or files as they are
calculated by the model.
The formatted plot file option for the POSTFILE keyword includes several lines of header
information, each identified with an asterisk (*) in column one. The header information includes
the model name and version number, the first line of the title information for the run, the list of
modeling option keywords applicable to the results, the averaging period and source group
included in the file, and the number of receptors included. The header also includes the format
used for writing the data records, and column headers for the variables included in the file. The
variables provided on each data record include the X and Y coordinates of the receptor location,
the concentration value for that location, receptor terrain elevation, hill height scale, flagpole
receptor height, the averaging period, the source group ID, and the either the date variable for the
end of the averaging period (in the form of YYMMDDHH) for short term averages or the number
of hours in the period for PERIOD averages. The following example from a formatted
postprocessor file for PERIOD averages identifies the contents of the POSTFILE:
AERMOD (02222) : A Simple Example Problem for the AERMOD Model with PRIME
MODELING OPTIONS USED:
CONC FLAT
POST/PLOT FILE OF PERIOD VALUES FOR SOURCE GROUP: ALL
FOR A TOTAL OF 144 RECEPTORS.
FORMAT: (3 (1X,F13 . 5) , 3 (IX, F8 . 2) , 2X, A6 , 2X, AS , 2X, 18 . 8 , 2X, AS )
30
60
86
173
59
119
171
342
87
175
X
38843
77686
82409
64818
85352
70705
01007
02014
50000
00000
Y AVERAGE CONC
172
344
492
984
164
328
469
939
151
303
34135
68271
40387
80774
44621
89243
84631
69263
55444
10889
0.12122
0.40298
0.72628
1.19873
0.12341
0.54534
1.15766
2.35508
0.12574
0.51807
ZELEV
0
0
0
0
0
0
0
0
0
0
00
00
00
00
00
00
00
00
00
00
ZHILL
0
0
0
0
0
0
0
0
0
0
00
00
00
00
00
00
00
00
00
00
ZFLAG
0
0
0
0
0
0
0
0
0
0
00
00
00
00
00
00
00
00
00
00
AVE
PERIOD
PERIOD
PERIOD
PERIOD
PERIOD
PERIOD
PERIOD
PERIOD
PERIOD
PERIOD
GRP
ALL
ALL
ALL
ALL
ALL
ALL
ALL
ALL
ALL
ALL
NUM HRS
00000096
00000096
00000096
00000096
00000096
00000096
00000096
00000096
00000096
00000096
NET ID
POL1
POL1
POL1
POL1
POL1
POL1
POL1
POL1
POL1
POL1
D-4
-------
D.4 HIGH VALUE RESULTS FOR PLOTTING (PLOTFILE OPTION)
The OU PLOTFILE card for the AERMOD model allows the user the option of creating
output files of highest concentration values suitable for importing into graphics software to
generate contour plots. The formatted plot files generated by the PLOTFILE include several lines
of header information, each identified with an asterisk (*) in column one. The header information
includes the model name and version number, the first line of the title information for the run, the
list of modeling option keywords applicable to the results, the averaging period and source group
included in the file, the high value (e.g. 2ND highest) included for plotting, and the number of
receptors included. The header also includes the format used for writing the data records, and
column headers for the variables included in the file. The variables provided on each data record
include the X and Y coordinates of the receptor location, the concentration value for that location,
receptor terrain elevation, hill height scale, flagpole receptor height, averaging period, the source
group ID, and either the high value included for short term averages or the number of hours in the
period for PERIOD averages. For short term averages, the PLOTFILE also includes the date
variable for the end of the averaging period (in the form of YYMMDDHH). The PERIOD
average PLOTFILE uses the same format for the data records as the PERIOD average formatted
POSTFILE shown in the previous section. The following example from a plot file for high
second highest 24-hour averages identifies the contents of the PLOTFILE:
AERMOD (02222): A Simple Example Problem f
MODELING OPTIONS USED:
CONC FLAT
PLOT FILE OF HIGH 2ND HIGH 24 -HR
FOR A TOTAL OF 144 RECEPTORS.
FORMAT
X
30.38843
60.77686
86.82409
173.64818
59.85352
119.70705
171.01007
342 .02014
87.50000
175.00000
(3 (1X,F13.5
172
344
492
984
164
328
469
939
151
303
Y
34135
68271
40387
80774
44621
89243
84631
69263
55444
10889
) ,3(1X,F8.2) ,3X
AVERAGE CONC
0.20960
0.53718
0. 92291
0. 95650
0 . 19456
0.53717
0. 92291
0. 95650
0. 19213
0.53711
or the AERMOD Model with PRIME
VALUES FOR SOURCE GROUP: ALL
,A5,2X,A8
ZELEV
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
,2X,A4,6X
ZHILL
0 .00
0 .00
0 .00
0 .00
0.00
0 .00
0 .00
0.00
0 .00
0 .00
,A8)
ZFLAG
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
AVE
24-HR
24-HR
24-HR
24-HR
24-HR
24-HR
24-HR
24-HR
24-HR
24-HR
GRP
ALL
ALL
ALL
ALL
ALL
ALL
ALL
ALL
ALL
ALL
HIVAL
2ND
2ND
2ND
2ND
2ND
2ND
2ND
2ND
2ND
2ND
NET ID
POL1
POL1
POL1
POL1
POL1
POL1
POL1
POL1
POL1
POL1
The PLOTFILE output also includes a flag ('**') identifying the receptor with the highest
concentration. For short term averages, the flag precedes the date field. For period averages, the
D-5
-------
flag precedes the field with the number of hours in the period.
D.5 TOXX MODEL INPUT FILES (TOXXFILE OPTION)
The OU TOXXFILE card for the AERMOD model allows the user the option to generate
an unformatted file or files of threshold violations for a specific averaging period for use with the
TOXX model component of TOXST. The file consists of three header records, including the first
line of the title information for the run, the number of source groups, receptors and averaging
periods, information on the type of receptor network, and the threshold cutoff value. Following
the header records are pairs of records identifying the specific averaging period, source group and
receptor location and corresponding concentration value for the values exceeding the user-
specified threshold. If any source group exceeds the threshold for a given averaging period and
receptor location, then the concentrations for all source groups are output for that period and
receptor. The structure of the unformatted file for the AERMOD model TOXXFILE option is
described below:
Record # Description
1 Title (80 characters)
2 IYEAR, NUMGRP, NUMREC, NUMPER, ITAB, NXTOX, NYTOX, IDUM1,
IDUM2, IDUM3
3 CUTOFF, RDUM1, ..., RDUM9
where: TITLE = First line of title (80 characters)
IYEAR = Year of simulation
NUMGRP = No. of source groups
NUMREC = Total no. of receptors
NUMPER = No. of averaging periods (e.g., number of hours in the year)
ITAB = 1 for polar grid; 2 for Cartesian grid; 0 for discrete receptors or
mixed grids
NXTOX = No. of x-coordinates (or distances) in receptor network
NYTOX = No. of y-coordinates (or directions) in receptor network
IDUM1, IDUM2, IDUM3 = dummy integer variables, arbitrarily set equal to zero
CUTOFF = User-specified threshold for outputting results (g/m3)
RDUM1, ..., RDUM9 = Dummy real variables (nine) arbitrarily set equal to zero
Following the header records, the file consists of pairs of records including an ID variable
D-6
-------
identifying the data period, source group number and receptor number, and the corresponding
concentration values. The number of values included in each record is controlled by the NPAIR
PARAMETER, which is initially set at 100 in MODULE MAIN1. The identification variable is
determined as follows:
IDCONC = IPER* 100000 + IGRP*1000 + IREC
where: IPER = the hour number for the year corresponding to the concentration value
IGRP = the source group number (the order in which the group was defined on
the SO pathway)
IREC = the receptor number (the order in which the receptor was defined on the
RE pathway)
D.6 MAXIMUM VALUES BY RANK (RANKFILE OPTION)
The OU RANKFILE card for the AERMOD model allows the user the option of creating
output files of the maximum concentration values by rank, suitable for generating Q-Q or quantile
plots. The data contained in the RANKFILE output is based on the MAXTABLE arrays, except
that only one occurrence per data period is included. The formatted data files generated by the
RANKFILE include several lines of header information, each identified with an asterisk (*) in
column one. The header information includes the model name and version number, the first line
of the title information for the run, the list of modeling option keywords applicable to the results,
the averaging period included in the file, and the number of ranked values included. The header
also includes the format used for writing the data records, and column headers for the variables
included in the file. The variables provided on each data record include the rank, concentration
value, X and Y coordinates of the receptor location, receptor terrain elevation, hill height scale,
flagpole receptor height, and the source group ID. Each RANKFILE includes results for all of the
source groups for a particular averaging period. Since the RANKFILE only include one
occurrence per data period, the file may not include the number of ranked values requested,
especially for evaluation data bases of limited duration. The following example identifies the
contents of the RANKFILE:
D-7
-------
AERMOD (02222): A Simple Example Problem for the AERMOD Model with PRIME
MODELING OPTIONS USED:
CONG FLAT
RANK-FILE OF UP TO 40 TOP 3-HR VALUES FOR I SOURCE GROUPS
INCLUDES OVERALL MAXIMUM VALUES WITH DUPLICATE DATA PERIODS REMOVED
FORMAT: (IX, 13, IX, F13.5, IX,18.8,2(IX,F13.5),3(IX,F7 . 2) ,2X,A8)
RANK AVERAGE CONG DATE X Y ZELEV ZHILL ZFLAG
GRP
D.7 ARC-MAXIMUM VALUES FOR EVALUATION (EVALFILE OPTION)
The OU EVALFILE card for the AERMOD model allows the user the option of creating
output files of the arc-maximum concentration values for individual sources suitable for use in
model evaluation studies. The data contained in the EVALFILE output is based on the maximum
value along arcs of receptors, identified using the RE EVALCART card. Receptors may be
grouped on arcs based on their distance from the source, or other logical grouping. The formatted
EVALFILE output includes five records of information for each selected source and each hour of
meteorological data. The information provided is as follows:
Record 1: Source ID (eight characters)
Date variable (YYMMDDHH)
Arc ID (eight characters)
Arc maximum x/Q
Emission rate for arc maximum (including unit conversions)
Crosswind integrated concentration based on true centerline concentration
Normalized non-dimensional crosswind integrated concentration
Record 2: Downwind distance corresponding to arc maximum (m)
Effective wind speed corresponding to arc maximum (m/s)
Effective ov corresponding to arc maximum (m/s)
Effective ow corresponding to arc maximum (m/s)
oy corresponding to arc maximum (m)
Effective plume height corresponding to arc maximum (m)
Record 3: Monin-Obukhov length for current hour (m)
Mixing height for current hour (m)
Surface friction velocity for current hour (m/s)
Convective velocity scale for current hour if unstable (m/s), or
oz for current hour if stable (m)
D-8
-------
Buoyancy flux for current hour (mVs3)
Momentum flux for current hour (mVs2)
Record 4: Bowen ratio for current hour
Plume penetration factor for current hour
Centerline x/Q for direct plume
Centerline x/Q for indirect plume
Centerline x/Q for penetrated plume
Nondimensional downwind distance
Record 5: Plume height/mixing height ratio
Non-dimensional buoyancy flux
Source release height (m)
Arc centerline x/Q
Developmental option settings place holder (string of 10 zeroes)
Flow vector for current hour (degrees)
Effective height for stable plume reflections (m)
The following Fortran WRITE and FORMAT statements are used to write the results to the
EVALFILE output:
WRITE(lELUNT(ISRC) ,9000) SRCID(ISRC), KURDAT, ARCID(I),
& ARCMAX(I), QMAX(I), CWIC, CWICN,
& DXMAX(I), UOUT, SVMAX(I),
& SWMAX(I) , SYOUT, HEMAX(I) ,
& OBULEN, ZI, USTAR, PWSTAR, FB, FM,
& BOWEN, PPF, CHIDML(I), CHINML(I), CHI3ML(I)
& XNDIM, HEOZI, FSTAR, AHS(ISRC), ARCCL(I),
& AFV, HSBLMX(I)
9000 FORMAT(IX,AS,IX,I8,IX,AS,4(1X,G12.6),
& /,9X,6(1X,G12.4),/,9X,6(1X,G12.4),
& /,9X,6(1X,G12.4),/,9X,4(lX,G12.4),IX,'0000000000',
& 1X,G12.4,1X,G12.4)
D.8 RESULTS BY SEASON AND HOUR-OF-DAY (SEASONHR OPTION)
The SEASONFIR option is used to output a file containing the average results by season
and hour-of-day. The formatted data files generated by the SEASONHR option include several
lines of header information, each identified with an asterisk (*) in column one. The header
information includes the model name and version number, the first line of the title information for
the run, the list of modeling option keywords applicable to the results, the source group included
in the file, and the number of receptors. The header also includes the format used for writing the
D-9
-------
data records, and column headers for the variables included in the file. The variables provided on
each data record include the X and Y coordinates of the receptor location, the average
concentration value, receptor terrain elevation, hill height scale, flagpole receptor height, source
group ID, number of non-calm and non-missing hours used to calculate the season-by-hour-of-
day averages (the NHRS column), season index (the SEAS column with 1 for winter, 2 for spring,
3 for summer, and 4 for fall), and the hour-of-day for the concentration value. A sample from a
SEASONHR output file is shown below:
AERMOD (02222): A Simple Example Problem for the AERMOD Model with PRIME
MODELING OPTIONS USED:
CONG FLAT
FILE OF SEASON/HOUR VALUES FOR SOURCE GROUP: ALL
FOR A TOTAL OF 144 RECEPTORS.
FORMAT: (2(IX,F13.5),1(IX,F13.8),3(IX,F7.2),2X,A3,2X,3(14,2X),A8)
X Y AVERAGE CONC ZELEV ZHILL ZFLAG GRP NHRS SEAS HOUR NET ID
ALL 421 POL1
D-10
-------
APPENDIX E.
QUICK REFERENCE FOR AERMOD
Type
TITLEONE
Titlel
TITLETWO
Title2
MODELOPT
DFAULT CONG FLAT NOSTD NOCHKD NOWARN SCREEN TOXICS SCIM
AVERTIME
Timel Time2 Time3 Time4 MONTH PERIOD ANNUAL
URBANOPT
POLLUTID
Pollut
HALFLIFE
Haflif
DCAYCOEF
FLAGPOLE
(Flagdf)
EVENTFIL
(Evfile) (Evopt)
SAVEFILE
INITFILE
MULTYEAR
H6H Savfil (Inifil)
DEBUGOPT
MODEL (Dbgfil) and/or METEOR (Dbmfil)
ERRORFIL
(Errfil)
SO Keyword:
ELEVUNIT
LOCATION
SRCPARAM
BUILDHGT
BUILDWID
XBADJ
YBADJ
AREAVERT
URBANSRC
EMI S FACT
EMISUNIT
HOUREMIS
INCLUDED
SRCGROUP
Type
0-N
M-R
M-R
0-R
0-R
0-R
0-R
0-R
0-R
0-R
0-N
0-R
0-R
M-R
Parameters
METERS or FEET
Srcid Srctyp Xs Ys (Zs) (Srctyp = POINT, VOLUME, or AREA)
Srcid Ptemis Stkhgt Stktmp Stkvel Stkdia (POINT Source)
Vlemis Relhgt Syinit Szinit (VOLUME Source)
Aremis Relhgt Xinit (Yinit) (Angle) (Szinit) (AREA Source)
Aremis Relhgt Nverts (Szinit) (AREAPOLY source)
Aremis Relhgt Radius (Nverts) (Szinit) (AREACIRC source)
Srcid (or Srcrng) Dsbh ( i) , i=l,Nsec
Srcid (or Srcrng) Dsbw(i) , i=l,Nsec
Srcid (or Srcrng) Xbadj (i) , i=l, Nsec
Srcid (or Srcrng) Ybadj (i) , i=l, Nsec
Srcid Xv(l) Yv ( 1 ) Xv(2) Yv ( 2 ) ... Xv(i) Yv(i)
Srcid' s and/or Srcrng' s
Srcid (or Srcrng) Qflag Qf act (i ) , i=l ,Nqf
Emifac Emilbl Conlbl
Emifil Srcid' s Srcrng' s
Incfil
Grpid Srcid' s Srcrng' s
Section
3 . 3
3.3.1
3.3.2
3.3.3
3.3.3
3.3.3
3.3.3
3.3.2
3.3.4
3.3.5
3.3.6
3.3.9
3.3.10
3.3.11
N - Non-repeatable
R - Repeatable
E-l
-------
RE Keywords
ELEVUNIT
GRIDCART
GRIDPOLR
DISCCART
EVALCART
DISCPOLR
INCLUDED
Type
0-N
0-R
0-R
0-R
0-R
0-R
0-R
Parameters
METERS or FEET
Netid STA
XYINC Xinit Xnum Xdelta Yinit Ynum Ydelta,
or XPNTS Gridxl Gridx2 Gridx3 . . . GridxN, and
YPNTS Gridyl Gridy2 Gridy3 . . . GridyN
ELEV Row Zelevl Zelev2 Zelev3 . . . ZelevN
HILL Row Zhilll Zhill2 Zhill3 . . . ZhillN
FLAG Row Zflagl Zflaci2 Zflag3 . . . ZflagN
END
Netid STA
ORIG Xinit Yinit,
or ORIG Srcid
DIST Rinql Rinci2 Ring3 . . . RinqN
DDIR Dirl Dir2 Dir3 . . . DirN,
or GDIR Dirnum Dirini Dirinc
ELEV Pad Zelevl Zelev2 Zelev3 . . . ZelevN
HILL Pad Zhilll Zhill2 ZhillS . . . ZhillN
FLAG Pad Zflagl Zflag2 Zflag3 . . . ZflagN
END
Xcoord Ycoord (Zelev Zhill) (Zflag)
Xcoord Ycoord Zelev Zhill Zflag Arcid (Name)
Srcid Range Direct (Zelev Zhill) (Zflag)
Incfil
Section
3.4
3.4.1
3.4.1
3.4.3
3.4.3
3.4.3
3.4.4
Note: While all RE keywords are optional, at least one receptor must be defined for each run.
ME Keywords
SURFFILE
PROFFILE
SURFDATA
UAIRDATA
SITEDATA
PROFBASE
STARTEND
DAYRANGE
SCIMBYHR
WDROTATE
WINDCATS
Type
M-N
M-N
M-N
M-N
0-N
M-N
0-N
0-R
0-N
0-N
0-N
Parameters
Sfcfil (Format)
Profil (Format)
Stanum Year (Name) (Xcoord Ycoord)
Stanum Year (Name) (Xcoord Ycoord)
Stanum Year (Name) (Xcoord Ycoord)
BaseElev (Units)
Strtyr Strtmn Strtdy (Strthr) Endyr Endmn Enddy (Endhr)
Rangel Range2 Range3 . . . RangeN
NRegStart NReglnt NWetStart NWetlnt (SfcFilnam PflFilnam)
Rotang
Wsl Ws2 Ws3 Ws4 Ws5
Section
3.5.1
3.5.1
3.5.2
3.5.2
3.5.2
3.5.3
3.5.4
3.5.4
3.5.7
3.5.5
3.5.6
EVENTPER
Evname Aveper Grpid Date
EVENTLOG
E-2
-------
OU Keywords
REG TABLE
MAX TABLE
DAY TABLE
MAXIFILE
PLOTFILE
POSTFILE
RANKFILE
EVALFILE
TOXXFILE
SEASONHR
EVENTOUT
Type
0-R
0-R
0-N
0-R
0-R
0-R
0-R
0-R
0-R
0-R
M-N
Parameters
Aveper FIRST SECOND . . . SIXTH or 1ST 2ND . . . 6TH
Aveper Maxnum
Avperl Avper2 Avper3 Avper4
Aveper Grpid Thresh Filnam (Funit)
Aveper Grpid Hivalu Filnam (Funit)
Aveper Grpid Filnam (Funit) (PERIOD or ANNUAL ave )
Aveper Grpid Format Filnam (Funit)
Aveper Hinum Filnam (Funit)
Srcid Filnam (Funit)
Aveper Cutoff Filnam (Funit)
GroupID Filenam (Funit)
SOCONT or DETAIL (Applies for EVENT processing only)
Section
3.7.1
3.7.1
3.7.1
3.7.2
3.7.2
3.7.2
3.7.2
3.7.2
3.7.2
3.7.2
3.7.2
373
E-3
-------
GLOSSARY
AERMAP -- AMS/EPA Regulatory Model (AERMOD) Terrain Preprocessor.
AERMET -- AMS/EPA Regulatory Model (AERMOD) Meteorological Preprocessor.
AERMOD -- AMS/EPA Regulatory Model.
ASCII — American Standard Code for Information Interchange, a standard set of codes used by
computers and communication devices. Sometimes used to refer to files containing only
such standard codes, without any application-specific codes such as might be present in a
document file from a word processor program.
CD-144 Format - Card Deck-144 data format available from NCDC for National Weather
Service surface observations commonly used for dispersion models. Each record
represents an 80-column "card image".
CO — COntrol, the 2-character pathway ID for input runstream images used to specify overall job
control options.
CO Pathway — Collective term for the group of input runstream images used to specify the
overall job control options, including titles, dispersion options, terrain options, etc.
Directory — A logical subdivision of a disk used to organize files stored on a disk.
Dispersion Model — A group of related mathematical algorithms used to estimate (model) the
dispersion of pollutants in the atmosphere due to transport by the mean (average) wind
and small scale turbulence.
DOS - Disk Operating System. Software that manages applications software and provides an
interface between applications and the system hardware components, such as the disk
drive, terminal, and keyboard.
Echo of inputs — By default, the AERMOD model will echo the input runstream images,
character by character, into the main printed output file. This serves as a record of the
inputs as originally entered by the user, without any rounding of the numerical values.
The echoing can be suppressed with the NO ECHO option.
EOF - End-of-File.
EPA — U. S. Environmental Protection Agency.
Error message — A message written by the model to the error/message file whenever an error is
encountered that will inhibit data processing.
GLOSSARY-1
-------
Error/Message File — A file used for storage of messages written by the model.
EV — EVent, the 2-character pathway ID for input runstream images used to specify event inputs
for the Short Term EVENT model.
EV Pathway — Collective term for the group of input runstream images used to specify the event
periods and location for the Short Term EVENT model.
EVENT Processing — An option in the AERMOD model specifically designed to provide source
contribution (culpability) information for specific events of interest, e.g., design values or
threshold violations.
Extended Memory — Additional memory on 80386 and 80486 PCs that allows programs to
address memory beyond the 640 KB limit of DOS. Special software is required to utilize
this extra memory.
Fatal Error — Any error which inhibits further processing of data by the model. Model continues
to read input images to check for errors during setup, and will continue to read input
meteorological data during calculation phase.
Flow Vector — The direction towards which the wind is blowing.
GMT — Greenwich Mean Time, the time at the 0° meridian.
Informational Message — Any message written to the error/message file that may be of interest to
the user, but which have no direct bearing on the validity of the results, and do not affect
processing.
Input Image — User supplied input, read through the default input device, controlling the model
options and data input. A single card or record from the input runstream file. Each input
image consists of a pathway ID (may be blank indicating a continuation of the previous
pathway), a keyword (may also be blank for continuation of a keyword), and possibly one
or more parameter fields.
Input Runstream File — The basic input file to the AERMOD model controlling the modeling
options, source data, receptor locations, meteorological data file specifications, and output
options. Consists of a series of input images grouped into functional pathways.
Julian Day — The number of the day in the year, i.e., Julian Day = 1 for January 1 and 365 (or 366
for leap years) for December 31.
KB — Kilobyte, 1000 bytes, a unit of storage on a disk
Keyword - The 8-character codes that follow immediately after the pathway ID in the input run
stream data.
GLOSSARY-2
-------
LST — Local Standard Time.
Math Co-processor — A computer chip used to speed up floating point arithmetic in a personal
computer.
MB — Megabyte, one million bytes, a unit of storage on a disk
ME — MEteorology, the 2-character pathway ID for input runstream images used to specify
meteorological data options
ME Pathway - Collective term for the group of input runstream images used to specify the input
meteorological data file and other meteorological variables, including the period to
process from the meteorological file for the AERMOD model.
Meteorological Data File — Any file containing meteorological data, whether it be mixing
heights, surface observations or on-site data.
Missing Value — Alphanumeric character(s) that represent breaks in the temporal or spatial record
of an atmospheric variable.
Mixing Height — The depth through which atmospheric pollutants are typically mixed by
dispersive processes.
NCDC — National Climatic Data Center, the federal agency responsible for distribution of the
National Weather Service upper air, mixing height and surface observation data.
NO ECHO — Option to suppress echoing of the runstream input images to the main printed output
file.
NWS — National Weather Service.
On-site Data — Data collected from a meteorological measurement program operated in the
vicinity of the site to be modeled in the dispersion analysis.
OU — OUtput, the 2-character pathway ID for input runstream images used to specify output
options.
OU Pathway - Collective term for the group of input runstream images used to specify the output
options for a particular run.
Overlay - One or more subprograms that reside on disk and are loaded into memory only when
needed.
Pasquill Stability Categories — A classification of the dispersive capacity of the atmosphere,
originally defined using surface wind speed, solar insolation (daytime) and cloudiness
GLOSSARY-3
-------
(nighttime). They have since been reinterpreted using various other meteorological
variables.
Pathway — One of the six major functional divisions in the input runstream file for the AERMOD
model. These are COntrol, SOurce, REceptor, MEteorology, EVent, and OUtput (see
these entries in this section for a description).
PC — Personal Computer, a wide ranging class of computers designed for personal use, typically
small enough to fit on a desktop.
Quality Assessment — Judgment of the quality of the data.
Quality Assessment Check — Determining if the reported value of a variable is reasonable (see
also Range Check).
Quality Assessment Message — Message written to the error/message file when a data value is
determined to be suspect.
Quality Assessment Violation — Occurrences when data values are determined to be suspect (see
also Range Check Violation).
RAM — Random Access Memory on a personal computer.
RAMMET — Meteorological processor program used for regulatory applications capable of
processing twice-daily mixing heights (TD-9689 format) and hourly surface weather
observations (CD-144 format) for use in dispersion models such as AERMOD, CRSTER,
MPTER and RAM.
Range Check — Determining if a variable falls within predefined upper and lower bounds.
Range Check Violation — Determination that the value of a variable is outside range defined by
upper and lower bound values (see also Quality Assessment Violation).
RE — REceptor, the 2-character pathway ID for input runstream images used to specify receptor
locations.
RE Pathway — Collective term for the group of input runstream images used to specify the
receptor locations for a particular run.
Regulatory Applications - Dispersion modeling involving regulatory decision-making as
described in the Guideline on Air Quality Models, which is published as Appendix W of
40 CFR Part 51 (as revised).
Regulatory Model — A dispersion model that has been approved for use by the regulatory offices
of the EPA, specifically one that is included in Appendix A of the Guideline on Air
Quality Models, (as revised), such as the AERMOD model.
GLOSSARY-4
-------
Runstream File — Collectively, all input images required to process input options and input data
for the AERMOD model.
SCRAM - Support Center for Regulatory Air Models - part of EPA's website on the internet,
used by EPA for disseminating air quality dispersion models, modeling guidance, and
related information.
Secondary Keyword — A descriptive alphabetical keyword used as a parameter for one of the
main runstream keywords to specify a particular option.
SO — SOurce, the 2-character pathway ID for input runstream images used to specify input
source parameters and source groups.
SO Pathway — Collective term for the group of input runstream images used to specify the source
input parameters and source group information.
Station Identification — An integer or character string used to uniquely identify a station or site as
provided in the upper air (TD-5600 and TD-6201), mixing height (TD-9689), and surface
weather (CD-144 and TD-3280) data formats available from NCDC. There are no
standard station numbers for on-site data or card image/screening data, and the user may
include any integer string
Subdirectory — A directory below the root, or highest level, directory or another subdirectory,
used for organization of files on a storage medium such as a PC hard disk.
Surface Weather Observations — A collection of atmospheric data on the state of the atmosphere
as observed from the earth's surface. In the U.S. the National Weather Service collect
these data on a regular basis at selected locations.
Surface Roughness Length — Height at which the wind speed extrapolated from a near-surface
wind speed profile becomes zero.
Syntax - The order, structure and arrangement of the inputs that make of the input runstream file,
specifically, the rules governing the placement of the various input elements including
pathway IDs, keywords, and parameters.
TD-1440 Format — A format available from NCDC for summarizing NWS surface observations
in an 80-column format; the CD-144 format is a subset of this format. This format has
been superseded by the TD-3280 format.
TD-3280 Format — The current format available from NCDC for summarizing NWS surface
weather observations in an elemental structure, i.e., observations of a single atmospheric
variable are grouped together for a designated period of time.
TD-5600 Format — A format available from NCDC for reporting NWS upper air sounding data.
This format has been superseded by the TD-6201 format.
GLOSSARY-5
-------
TD-6201 Format — The current format available from NCDC for reporting NWS upper air data.
The file structure is essentially the same as the TD-5600 format except that there is more
quality assurance information.
TD-9689 Format — The format available from NCDC for mixing heights estimated from morning
upper air temperature and pressure data and hourly surface observations of temperature.
Unformatted File -- A file written without the use of a FORTRAN FORMAT statement,
sometimes referred to as a binary file.
Upper Air Data (or soundings) — Meteorological data obtained from balloon- borne
instrumentation that provides information on pressure, temperature, humidity, and wind
away from the surface of the earth.
Vertical Potential Temperature Gradient — The change of potential temperature with height, used
in modeling the plume rise through a stable layer, and indicates the strength of the stable
temperature inversion. A positive value means that potential temperature increases with
height above ground and indicates a stable atmosphere.
Warning Message — A message written by the model to the error/message file whenever a
problem arises that may reflect an erroneous condition, but does not inhibit further
processing.
GLOSSARY-6
-------
TECHNICAL REPORT DATA
(Please read Instructions on reverse before completing)
1. REPORT NO.
EPA-454/B-03-001
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
User's Guide for the AMS/EPA Regulatory Model- AERMOD
5. REORT DATE
September 2004
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
10. PROGRAM ELEMENT NO.
See below.
11. CONTRACT/GRANT NO. 68D300326,
68D30001, 68D70069
12. SPONSORING AGENCY NAME AND ADDRESS
U.S. Environmental Protection Agency
Office of Air Quality Planning and Standards
Emissions Monitoring and Analysis Division
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final technical report.
14. SPONSORING AGENCY CODE
EPA/200/04
15. SUPPLEMENTARY NOTES
16. ABSTRACT This User's Guide for the AMS/EPA Regulatory Model (AERMOD) provides user
instructions for the AERMOD model. The technical description of the AERMOD algorithms is provided in a
separate document. The revised AERMOD model described in this user's guide includes the following
modifications and enhancements: the PRIME building downwash algorithms based on the ISC-PRIME
model; use of allocatable arrays for data storage; incorporation of EVENT processing for analyzing short-
term source culpability; post-1997 PM10 processing; a non-regulatory default TOXICS option that includes
optimizations for area sources and the Sampled Chronological Input Model (SCIM) option; explicit treatment
of multiple-year meteorological data files and the ANNUAL average; and options to specify emissions that
vary by season, hour-of-day and day-of-week.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b. IDENTIFIERS/OPEN ENDED TERMS
c. COSATT Field/Group
AERMOD, user's guide, air dispersion model,
Air Pollution models
18. DISTRIBUTION STATEMENT
Release Unlimited
19. SECURITY CLASS (Report)
21. No of pages 227
20. SECURITY CLASS (Page)
. PRICE free
EPA Form 2220-1 (Rev. 4-77) PREVIOUS EDITION IS OBSOLETE
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