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User's Guide for AERSURFACE Tool
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EPA-454/B-24-003
November 2024
User's Guide for AERSURFACE Tool
U.S. Environmental Protection Agency
Office of Air Quality Planning and Standards
Air Quality Assessment Division
Research Triangle Park, NC
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Preface
This document provides a technical description and user instructions specific to the
AERSURFACE tool, version 24142 (dated May 22, 2024, representative of the code lock date).
AERSURFACE was designed to aid in determining surface characteristic values required by
AERMET, the meteorological processor for AERMOD. This version, 24142, includes minor
updates and replaces version 20060. The updates in version 24142 have expanded the capability to
read and process all available years (i.e., 1985 - 2023) of Annual National Land Cover Database
(NLCD) land cover data which can be supplemented with percent tree canopy and percent
impervious where available. Version 24142 maintains the interface that uses the path/keyword
approach read from a control file, similar to AERMET, AERMAP, and AERMOD.
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Contents
Section Page
1.0 Introduction 1-1
1.1 When to Use AERSURFACE 1-1
1.2 Changes from Version 20060 to 24142 1-3
1.3 Status of AERSURFACE, Version 24142 1-3
2.0 Technical Description of AERSURFACE 2-4
2.1 Description of the National Land Cover Database 2-5
2.2NLCD Sources 2-9
2.3 Assignment of Surface Characteristics by Land Cover Category 2-9
2.3.1 Seasonal Values 2-10
2.3.2 Surface Roughness Adjustments by Sector 2-11
2.3.3 Climate 2-13
2.4 AERSURFACE Calculation Methods 2-14
2.4.1 Surface Roughness Length 2-15
2.4.1.1 ZORAD - Default Method for Determining Roughness Length 2-16
2.4.1.2 ZOEFF - Experimental Method for Determining Roughness Length 2-17
2.4.1.3 Supplemental Percent Impervious and Canopy Data 2-18
2.4.2 Daytime Bowen Ratio 2-20
2.4.3 Noontime Albedo 2-21
3.0 Detailed keyword reference 3-1
3.1 Overview 3-1
3.1.1 Pathway IDs 3-1
3.1.2 Starting and ending a Pathway Block 3-2
3.1.3 Blank Lines and Comments 3-2
3.2 Control Pathway (CO) 3-3
3.2.1 Title information (TITLEONE, TITLETWO) 3-3
3.2.2 Options (OPTIONS) 3-4
3.2.3 Debug Options (DEBUGOPT) 3-5
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3.2.4 Location of Meteorological Tower (CENTERXY, CENTERLL) 3-6
3.2.5 NLCD Filenames (DATAFILE) 3-8
3.2.6 Fixed Radial Distance for Roughness (ZORADIUS) 3-10
3.2.7 Anemometer Height (ANEM_HGT) 3-10
3.2.8 Climate, Surface Moisture, and Continuous Snow Cover (CLIMATE) 3-12
3.2.9 Temporal Frequency (FREQ_SECT) 3-14
3.2.10 Surface Roughness Length Wind Sectors (SECTOR) 3-15
3.2.11 Assigning Months to Seasons (SEASON) 3-17
3.2.12 To Run or Not (RUNORNOT) 3-18
3.3 Output Pathway (OU) 3-19
3.3.1 Surface Characteristic Values File for AERMET (SFCCHAR) 3-19
3.3.2 Debug Output Files 3-20
3.4 Sample AERSURFACE Control File 3-22
4.0 Running AERSURFACE 4-1
4.1 Command Prompt and Command-line Arguments 4-1
4.2 Error and Warning Messages 4-2
4.3 Summary of Output Files Generated by AERSURFACE 4-2
4.3.1 Auto-generated Files 4-3
4.3.1. 1 Summary File (aersurface.out) 4-3
4.3.1,2 Log File (aersurface.log) 4-3
4.3.2 Surface Characteristics 4-4
4.3.3 Debug Files 4-4
4.3.3.1 Effective Radius File (default = effective radtxt) 4-5
4.3.3.2 TIFF Debug Files (defaults = lc_tif_dbg.txt, imp_tif_dbg.txt, and
can tif dbg. txt) 4-5
4.3.3.3 Grid Files (defaults = landcover.txt, impervious.txt, and canopy.txt) 4-6
5.0 Appendix A: National Land Cover Database Definitions 5-1
6.0 Appendix B. Surface Characteristic Lookup Tables 6-1
7.0 Appendix C. Alphabetical keyword reference 7-1
8,0 Appendix D. Functional keyword/parameter reference 8-1
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9,0 Appendix E: Implementation of ZOEFF Option in AERSURFACE, Version 20060 9-1
9.1 Method 9-1
9.2 Scientific Basis 9-1
9.3 Implementation 9-3
10.0 Appendix F: Venkatram Model Coding Abstract - Estimating Effective Roughness 10-1
11,0 Appendix G: Inter-comparison of AERSURFACE 11-1
11.1 AERSURFACE Scenarios and Meteorological Data Processing with AERMET 11-2
11.2 Emission Sources and AERMOD Setup 11-17
11.3 Inter-comparison of AERSURFACE and AERMOD Results 11-19
11.4 Comparison of Surface Roughness Length Estimated with 2001 NLCD (2011 Edition) and
2016 NLCD 11-40
12.0 Appendix H: Error and Warning Messages 12-1
13.0 References 13-4
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Figures
Figure 2-1. Surface Roughness Value Adjustment to Annual NLCD Developed Categories (21-24)
Using Percent Impervious and Canopy Data 2-20
Figure 3-1. Sample AERSURFACE Control File 3-24
Figure 3-2. 2016 NLCD for RDU International with Wind Sectors Starting at 30, 60, and 225
Degrees 3-25
Figure 9-1. Concentric Rings Defined around Meteorological Tower to Calculate IBL Growth... 9-4
Figure 11-1. ATL 10 x 10 km Area and 1 km Radius with Wind Sectors 11-6
Figure 11-2. BTR: 10x10 km Area and 1 km Radius with Wind Sectors 11-7
Figure 11-3. RDU: 10x10 km Area and 1 km Radius with Wind Sectors 11-8
Figure 11-4. 2001 NLCD (2011 Edition) Land Cover for ATL 11-10
Figure 11-5. 2001 NLCD (2011 Edition) Percent Impervious and Percent Canopy for ATL ....11-11
Figure 11-6. 1992 NLCD Land Cover for BTR 11-12
Figure 11-7. 2001 NLCD (2011 Edition) Land Cover for BTR 11-13
Figure 11-8. 2001 NLCD (2011 Edition) Percent Impervious and Percent Canopy for BTR... 11-14
Figure 11-9. 2001 NLCD (2011 Edition) Land Cover for RDU 11-15
Figure 11-10. 2001 NLCD (2011 Edition) Percent Impervious and Percent Canopy for RDU.. 11-16
Figure 11-11. ATL Surface Roughness Length by Season, Sector, and AERSURFACE Scenario 11-
22
Figure 11-12. ATL H1H Predicted Concentrations by AERSURFACE Scenario and Emission
Source 11-23
Figure 11-13. ATL H2H Predicted Concentrations by AERSURFACE Scenario and Emission
Source 11-24
Figure 11-14. ATL, Scatter Plots, H1H and H2H at each Receptor, 2001 Base Case, LC-IMP-
CAN-ZORAD Vs. 2001 LC-IMP-CAN-ZOEFF 11-25
Figure 11-15. ATL, Scatter Plots, H1H and H2H at each Receptor, 2001 Base Case, LC-IMP-
C.W-ZORAD Vs. 2001 LC-IMP-ZORAD 11-2
Figure 11-16. ATL, Scatter Plots, H1H and H2H at each Receptor, 2001 Base Case, LC-IMP-
C.W-ZORAD Vs. 2001 LC-IMP-ZOEFF 11-3
Figure 11-17. ATL, Scatter Plots, H1H and H2H at each Receptor, 2001 Base Case, LC-IMP-
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CAN-ZORAD Vs. 2001 LC-CAN-ZORAD
11-4
Figure 11-18. ATL, Scatter Plots, H1H and H2H at each Receptor, 2001 Base Case, LC-IMP-
CAN-ZORAD Vs. 2001 LC-CAN-ZOEFF 11-5
Figure 11-19. ATL, Scatter Plots, H1H and H2H at each Receptor, 2001 Base Case, LC-IMP-
CAN-ZORAD Vs. 2001 LC-ZORAD 11-6
Figure 11-20. ATL, Scatter Plots, H1H and H2H at each Receptor, 2001 Base Case, LC-IMP-
CAN-ZORAD Vs. 2001 LC-ZOEFF 11-7
Figure 11-21. ATL, Scatter Plots, H1H and H2H at each Receptor, 2001 LC-IMP-ZORAD Vs.
2001 LC-IMP-ZOEFF 11-8
Figure 11-22. ATL, Scatter Plots, H1H and H2H at each Receptor, 2001 LC-CAN-ZORAD Vs.
2001 LC-CAN-ZOEFF 11-9
Figure 11-23. ATL, Scatter Plots, H1H and H2H at each Receptor, 2001 LC-ZORAD Vs. 2001
LC-ZOEFF 11-10
Figure 11-24. BTR Surface Roughness Length by Season, Sector, and AERSURFACE Scenario 11-
11
Figure 11-25. BTR H1H Predicted Concentrations by AERSURFACE Scenario and Emission
Source 11-12
Figure 11-26. BTR H2H Predicted Concentrations by AERSURFACE Scenario and Emission
Source 11-13
Figure 11-27. BTR, Scatter Plots, H1H and H2H at each Receptor, 2001 Base Case, LC-IMP-
C.W-ZORAD Vs. 1992 LC-ZORAD 11-14
Figure 11-28. BTR, Scatter Plots, H1H and H2H at each Receptor, 2001 Base Case, LC-IMP-
CAN-ZORAD Vs. 1992 LC-ZOEFF 11-15
Figure 11-29. BTR, Scatter Plots, H1H and H2H at each Receptor, 2001 Base Case, LC-IMP-
CAN-ZORAD Vs. 2001 LC-IMP-CAN-ZOEFF 11-16
Figure 11-30. BTR, Scatter Plots, H1H and H2H at each Receptor, 2001 Base Case, LC-IMP-
CAN-ZORAD Vs. 2001 LC-IMP-ZORAD 11-17
Figure 11-31. BTR, Scatter Plots, H1H and H2H at each Receptor, 2001 Base Case, LC-IMP-
CAN-ZORAD Vs. 2001 LC-IMP-ZOEFF 11-18
Figure 11-32. BTR, Scatter Plots, H1H and H2H at each Receptor, 2001 Base Case, LC-IMP-
CAN-ZORAD Vs. 2001 LC-CAN-ZORAD 11-19
Figure 11-33. BTR, Scatter Plots, H1H and H2H at each Receptor, 2001 Base Case, LC-IMP-
CAN-ZORAD Vs. 2001 LC-CAN-ZOEFF 11-20
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Figure 11-34. BTR, Scatter Plots, H1H and H2H at each Receptor, 2001 Base Case, LC-IMP-
CAN-ZORAD Vs. 2001 LC-ZORAD 11-21
Figure 11-35. BTR, Scatter Plots, H1H and H2H at each Receptor, 2001 Base Case, LC-IMP-
CAN-ZORAD Vs. 2001 LC-ZOEFF 11-22
Figure 11-36. BTR, Scatter Plots, H1H and H2H at each Receptor, 1992 LC-ZORAD Vs. 1992
LC-ZOEFF 11-23
Figure 11-37. BTR, Q-Q Plots, H1H and H2H at each Receptor, 2001 LC-IMP-ZORAD Vs. 2001
LC-IMP-ZOEFF 11-24
Figure 11-38. BTR, Scatter Plots, H1H and H2H at each Receptor, 2001 LC-CAN-ZORAD Vs.
2001 LC-CAN-ZOEFF 11-25
Figure 11-39. BTR, Scatter Plots, H1H and H2H at each Receptor, 2001 LC-ZORAD Vs. 2001
LC-ZOEFF 11-26
Figure 11-40. RDU Surface Roughness Length by Season, Sector, and AERSURFACE Scenario
11-27
Figure 11-41. RDU H1H Predicted Concentrations by AERSURFACE Scenario and Emission
Source 11-28
Figure 11-42. RDU H2H Predicted Concentrations by AERSURFACE Scenario and Emission
Source 11-29
Figure 11-43. RDU, Scatter Plots, H1H and H2H at each Receptor, 2001 Base Case, LC-IMP-
CAN-ZORAD Vs. 2001 LC-IMP-CAN-ZOEFF 11-30
Figure 11-44. RDU, Scatter Plots, H1H and H2H at each Receptor, 2001 Base Case, LC-IMP-
CAN-ZORAD Vs. 2001 LC-IMP-ZORAD 11-31
Figure 11-45. RDU, Scatter Plots, H1H and H2H at each Receptor, 2001 Base Case, LC-IMP-
CAN-ZORAD Vs. 2001 LC-IMP-ZOEFF 11-32
Figure 11-46. RDU, Scatter Plots, H1H and H2H at each Receptor, 2001 Base Case, LC-IMP-
CAN-ZORAD Vs. 2001 LC-CAN-ZORAD 11-33
Figure 11-47. RDU, Scatter Plots, H1H and H2H at each Receptor, 2001 Base Case, LC-IMP-
CAN-ZORAD Vs. 2001 LC-CAN-ZOEFF 11-34
Figure 11-48. RDU, Scatter Plots, H1H and H2H at each Receptor, 2001 Base Case, LC-IMP-
C.W-ZORAD Vs. 2001 LC-ZORAD 11-35
Figure 11-49. RDU, Scatter Plots, H1H and H2H at each Receptor, 2001 Base Case, LC-IMP-
CAN-ZORAD Vs. 2001 LC-ZOEFF 11-36
Figure 11-50. RDU, Scatter Plots, H1H and H2H at each Receptor, 2001 LC-IMP-ZORAD Vs.
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2001 LC-IMP-ZOEFF 11-37
Figure 11-51. RDU, Scatter Plots, H1H and H2H at each Receptor, 2001 LC-CAN-ZORAD Vs.
2001 LC-CAN-ZOEFF 11-38
Figure 11-52. RDU, Scatter Plots, H1H and H2H at each Receptor, 2001 LC-ZORAD Vs. 2001
LC-ZOEFF 11-39
Figure 11-53. Comparison of 2001 NLCD (2011 Edition) to 2016 NLCD for ATL 11-41
Figure 11-54. Surface Roughness Length Estimated for ATL using 2001 NLCD (2011 Edition) and
2016 NLCD 11-42
Figure 11-55. Surface Roughness Length Estimated for ATL using 2001 NLCD (2011 Edition) and
2016 NLCD 11-43
Figure 11-56. Comparison of 2001 NLCD (2011 Edition) to 2016 NLCD for BTR 11-44
Figure 11-57. Surface Roughness Length Estimated for BTR using 2001 NLCD (2011 Edition) and
2016 NLCD 11-45
Figure 11-58. Surface Roughness Length Estimated for BTR using 2001 NLCD (2011 Edition) and
2016 NLCD 11-46
Figure 11-59. Comparison of 2001 NLCD (2011 Edition) to 2016 NLCD for RDU BTR 11-47
Figure 11-60. Surface Roughness Length Estimated for RDU using 2001 NLCD (2011 Edition)
and 2016 NLCD 11-48
Figure 11-61. Surface Roughness Length Estimated for RDU using 2001 NLCD (2011 Edition)
and 2016 NLCD 11-49
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Tables
Table 2-1. Original 1992 NLCD Classification Categories 2-7
Table 2-2. Annual NLCD Classification Categories 2-8
Table 2-3. AERSURFACE Season Definitions 2-11
Table 3-1. Default Month/Season Assignments in AERMET 3-14
Table 3-2. Season Secondary Keywords and Definitions 3-18
Table 3-3. OU Pathway Primary Keywords and Default Filenames 3-21
Table 5-1. Original 1992 NLCD Class and Category Descriptions and Color Legend 5-1
Table 5-2. Annual NLCD Class and Category Descriptions and Color Legend 5-3
Table 6-1. Seasonal Values of Albedo for the original 1992 NLCD 6-2
Table 6-2. Seasonal Values of Bowen Ratio for the original 1992 NLCD 6-4
Table 6-3. Seasonal Values of Surface Roughness (m) for the original 1992 NLCD 6-6
Table 6-4. Seasonal Values of Albedo for the Annual NLCD 6-8
Table 6-5. Seasonal Values of Bowen Ratio for the Annual NLCD 6-9
Table 6-6. Seasonal Values of Surface Roughness for the Annual NLCD 6-11
Table 7-1. All Primary Keywords Available in AERSURFACE 7-2
Table 8-1. Description of Control Pathway Keywords 8-2
Table 8-2. Description of Control Pathway Keywords and Parameters 8-3
Table 8-3. Description of Output Pathway Keywords 8-8
Table 8-4. Description of Output Pathway Keywords and Parameters 8-8
Table 11-1. 2001 NLCD (2011 Edition) AERSURFACE Scenarios for ATL, BTR, and RDU ..11-2
Table 11-2. 1992 NLCD AERSURFACE Scenarios for BTR 11-3
Table 11-3. NWS/FAA Meteorological Tower Location and Wind Sector Definitions 11-5
Table 11-4. Surface and Upper Air Station Pairings for Meteorological Data Processing 11-17
Table 11-5. Emission Sources 11-18
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1.0 Introduction
When applying the AERMET meteorological processor (EPA, 2024a) to process
meteorological data for the AERMOD model (EPA, 2024b), the user must determine
appropriate values for three surface characteristics: surface roughness length, noontime
albedo, and daytime Bowen ratio. The surface roughness length is related to the height of
obstacles to the wind flow and is, in principle, the height at which the mean horizontal wind
speed is zero based on a logarithmic profile. The surface roughness length influences the
surface shear stress and is an important factor in determining the magnitude of mechanical
turbulence and the stability of the boundary layer. The albedo is the fraction of total incident
solar radiation reflected by the surface back to space without absorption. The Bowen ratio, an
indicator of surface moisture, is the ratio of sensible heat flux to latent heat flux and, together
with albedo and other meteorological observations, is used for determining planetary boundary
layer parameters for convective conditions driven by the surface sensible heat flux. Further
details regarding the AERMOD model formulations and their dependence on surface
characteristics are provided in Cimorelli, et al. (2004).
The AERSURFACE tool has been developed to aid users in obtaining realistic and
reproducible surface characteristic values for albedo, Bowen ratio, and surface roughness
length, for input to AERMET. The tool uses data from the National Land Cover Database
(NLCD) from the United States Geological Survey (USGS) and look-up tables of surface
characteristic values that vary by land cover type and season. This user's guide provides a
technical description of the AERSURFACE tool, including information on the data used by
AERSURFACE to provide these surface characteristics for AERMET. Detailed user
instructions for application of AERSURFACE are also provided.
1.1 When to Use AERSURFACE
User-defined values for the surface characteristics referenced above must be developed
for input to AERMET when processing site-specific surface meteorology, commonly collected
onsite near the emission source, and/or surface meteorology collected at National Weather
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Service (NWS)ZFederal Aviation Administration (FAA) surface meteorological stations,
typically located at airports across the country. AERMET can also accept prognostic
meteorology generated by the Weather Research Forecast (WRF) model and extracted using
the Mesoscale Model Interface (MMIF) program (EPA, 2019b). User-defined surface
characteristics are not needed when prognostic data are extracted using MMIF since surface
characteristics are included in the formatted MMIF output.
When processing site-specific and NWS/FAA surface data simultaneously with
AERMET and the NWS/FAA wind data are used to substitute missing site-specific wind data,
AERMET requires user-defined surface characteristic values for both meteorological station
locations. In that case, the site-specific station is considered the primary site, and the
NWS/FAA site is considered the secondary site. When NWS/FAA surface data are processed
without site-specific data, the NWS/FAA site is considered the primary site since it is the only
source of surface meteorology.
AERSURFACE is not a regulatory component of the AERMOD Modeling System as
listed in Appendix A to the Guideline on Air Quality Models (published as "Appendix W" to
40 CFR Part 51), which includes the AERMAP and AERMET terrain and meteorological
preprocessors, respectively, in addition to the AERMOD dispersion model. However, Section
8.4.2(b) of the Guideline recommends the use of the latest version of AERSURFACE for
determining surface characteristics when processing measured meteorological data through
AERMET (i.e., representative site-specific data or data from a nearby National Weather
Service or comparable station). Where it is not possible to run AERSURFACE, Section
8.4.2(b) recommends using the methods in AERSURFACE to determine surface characteristic
values. The methods implemented in AERSURFACE are also discussed in the AERMOD
Implementation Guide (EPA, 2024c).
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1.2 Changes from Version 20060 to 24142
AERSURFACE has been updated from version 20060 to version 24142 (dated May
22, 2024, representative of the code lock date). This version represents refined updates to
version 20060 to improve user experience. The updates include:
Added additional file checks for user input files (i.e., land cover, impervious,
and canopy data).
Updated the DATAFILE keyword to allow processing of all current and future
NLCD years which can be supplemented with perent impervious and percent
tree canopy data, where available.
Renames the Airport (AP) and Non-Airport (NONAP) flags to LOWZO and
HIGHZ0 respectively to improve user understanding of when to apply these
flags.
Made changes to the file resolution tolerance to accommodate for NLCD files
downloaded from the MRLC that do not have an exact 30 x 30-meter
resolution.
• Made updates to prevent users from using input files (i.e., land cover,
impervious, and canopy data) with grid sizes less than or equal to 10 x 10-
kilometer.
1.3 Status of AERSURFACE, Version 24142
The EPA is releasing AERSURFACE version 24142 as a replacement for version 20060. The
EPA recommends the following when using version 24142 of the AERSURFACE tool:
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• The default method for determining surface roughness length (ZORAD) should
be used. The ZOEFF method is considered research grade and should be used
only for testing and evaluation purposes.
• Land cover data should only be supplemented with concurrent percent
impervious and percent tree canopy data (i.e., data representative of one year
should not be substituted for another year).
• For the NLCD year of the land cover being processed, if only one of
impervious or tree canopy data is available, or neither is available, then the land
cover data should be processed by itself without the use of the impervious or
tree canopy data. Land cover data should not be supplemented with impervious
data only or tree canopy data only.
As an example, to demonstration the last two bulleted items above, the 2023 NLCD
includes land cover and percent impervious data for the conterminous US (CONUS) but does
not include percent tree canopy data. When relying on the 2023 NLCD to determine surface
characteristic values for input to AERMET, the 2023 land cover should be processed with
AERSURFACE by itself and not supplemented with percent impervious and/or percent tree
canopy data since the 2023 NLCD does not include both percent impervious and percent tree
canopy data that are concurrent with the 2023 land cover data.
2,0 Technical Description of AERSURFACE
This section discusses the land cover data that are input to AERSURFACE and a
technical description of how those data are processed to determine representative values of
albedo, Bowen ratio, and surface roughness length.
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2.1 Description of the National Land Cover Database
AERSURFACE requires the input of land cover data from the NLCD to determine the
land cover types at a user-specified location. NLCD products are created by the Multi-
Resolution Land Characteristics Consortium (MRLC), https://www.mrlc.gov/) a partnership of
Federal agencies led by the USGS and serves as the definitive Landsat-based land cover
database for the Nation. At the time of the release of AERSURFACE version 24142, the
MRLC has released annual NLCD products for the contiguous US (CONUS) for all years
between 1985 and 2023. The release of the 2024 Annual NLCD updates the previous 2021
versions of landcover products. Version 24142 of AERSURFACE has been modified to accept
all annual NLCD years as well as new years of NLCD data as they are released.
The original 1992 NLCD used a 21-class land cover classification scheme. With the
2024 NLCD updates, all years of available land cover data (i.e., 1985 - 2023) now use the 16
Anderson Level II classes. Beginning with the 2001 NLCD, the datasets were expanded to
include land cover for Alaska, Hawaii, and Puerto Rico for certain years. In addition, new
products were added to the NLCD to include data which supplement the land cover data with
the percent area of the surface in a land cover grid cell that is impervious material and the
percent area of the grid cell that is covered with a tree canopy. Percent impervious data is
available for all annual NLCD years (i.e., 1985 - 2023) and tree canopy data is available for
2011 through 2021 for CONUS. AERSURFACE version 24142 has the capability to process
the impervious and tree canopy data as a supplement to land cover. Refer to EPA's
recommendations above for processing NLCD files based on available data products. Refer to
the Multi-Resolution Land Characteristics (MRLC) Consortium website at
https://www.mrlc.gov for information on NLCD data products.
Note: The USGS has indicated that support for the original 1992 NLCD has been
discontinued and will no longer distribute the original 1992 NLCD, though the capability
to process the 1992 NLCD has been retained in AERSURFACE version 24142. Sources
for obtaining model-ready NLCD files are provided in Section 2.2. Also note, as with
19039 DRFT and version 20060, the 1992 NLCD "binary" (.bin) state files, previously
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available from the USGS, are not supported by AERSURFACE version 24142. Future
versions of AERSURFACE will no longer support the original 1992 NLCD and the EPA
encourages users to switch to the new annual NLCD products available from the MRLC.
The NLCD identifies the predominant land cover at a resolution of 30 x 30-meter grid
cells. Recently, in 2024, land cover files downloaded from the MRLC have not had exact 30 x
30-meter grid resolutions. The resolutions of some files have been off by as much as five
hundredths of a meter. AERSURFACE version 24142 has an increased file resolution
tolerance to accommodate for the resolution differences we have observed.
AERSURFACE assigns each land cover category within each 30 x 30-meter land
cover grid cell seasonal values of albedo, Bowen ratio, and surface roughness. Temporally
representative average values (e.g., annual, seasonal, or monthly) are calculated for the area of
interest from the seasonal values. AERSURFACE results are output in a format that is input
ready for AERMET.
The original 1992 NLCD is based on a 21-category system while the current annual
NLCDs use a 16-category system with 4 additional categories that are specific to Alaska.
Category codes and names for each of the two classification systems are shown in Table 2-1
and Table 2-2. Complete category descriptions are provided in Section 5.0. The seasonal
values assigned to albedo, Bowen ratio, and surface roughness length, by land cover category,
for each of the two classification systems (original 1992 NLCD and annual NLCD) are
provided in Section 6.0. Discussions of the methods implemented in AERSURFACE to
calculate representative values for the three surface characteristics (albedo, Bowen ratio, and
roughness length) are provided in Section 2.4.
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Table 2-1. Original 1992 NLCD Classification Categories
Classification
Category
Number
Category Name
Water
11
Open Water
12
Perennial Ice/Snow
Developed
21
Low Intensity Residential
22
High Intensity Residential
23
Commercial/Industrial/Transportation
Barren
31
Bare Rock/Sand/Clay
32
Quarries/Strip Mines/Gravel Pits
33
Transitional
Forested Upland
41
Deciduous Forest
42
Evergreen Forest
43
Mixed Forest
Shrubland
51
Shrubland
Non-natural Woody
61
Orchards/Vineyards/Other
Herbaceous Upland
71
Grasslands/Herbaceous
Herbaceous
Planted/Cultivated
81
Pasture/Hay
82
Row Crops
83
Small Grains
84
Fallow
85
Urban/Recreational Grasses
Wetlands
91
Woody Wetlands
92
Emergent Herbaceous Wetlands
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Table 2-2. Annual NLCD Classification Categories
Classification
Category
Number
Category Name
Water
11
Open Water
12
Perennial Ice/Snow
Developed
21
Developed, Open Space
22
Developed, Low Intensity
23
Developed, Medium Intensity
24
Developed, High Intensity
Barren
31
Bare Land (Rock/Sand/Clay)
Forest
41
Deciduous Forest
42
Evergreen Forest
43
Mixed Forest
Shrubland
51
Dwarf Scrub (Alaska Only)
52
Shrub/Scrub
Herbaceous
71
Grassland/Herbaceous
72
Sedge/Herbaceous (Alaska Only)
73
Lichens (Alaska Only)
74
Moss (Alaska Only)
Planted/Cultivated
81
Pasture/Hay
82
Cultivated Crops
Wetlands
90
Woody Wetlands
95
Emergent Herbaceous Wetlands
Versions of AERSURFACE prior to 19039 DRFT were limited to the use of the
original 1992 NCLD which subsequently limited its application to the conterminous U.S. As
previously stated, AERSURFACE can now process land cover data from the 1985 to 2023
NLCDs. Where available, percent impervious and percent tree canopy data can be input into
AERSURFACE to supplement land cover data. This is a refinement for certain annual NLCD
land cover categories that are more difficult to assign roughness values due to a broader
characterization of land cover for those categories (e.g., the "Developed" categories in the
annual NLCD classification).
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The NLCD files processed by AERSURFACE require a spatial resolution of 30 meters,
mapped using an Albers Conic Equal Area projection. The files input to AERSURFACE must
be in the Georeferenced Tagged Image File Format (GeoTIFF) (Aldus, 1992; Ritter and Ruth,
1995). In addition, AERSURFACE requires that the land cover data are stored in the GeoTIFF
as a single byte (8-bit) integer and the data are not compressed.
Note: The USGS no longer supports the original 1992 NLCD as it has been
replaced by the new annual NLCD products. Further, the MRLC website will no longer
distribute the 1992 NLCD. Sources for obtaining model-ready NLCD GeoTIFF files are
provided in Section 2.2. Also note, as with 19039 DRFT and version 20060, the 1992
NLCD "binary" (.bin) state files, previously available from the USGS, are not supported
by AERSURFACE version 24142.
2.2 NLCD Sources
Refer to the "NLCD Sources for AERSURFACE" file on EPA's SCRAM website for
the most up to date information on where and how to obtain NLCD products for the
conterminous US, Alaska, Hawaii, and Puerto Rico for use with AERSURFACE. The MRLC
Consortium (https://www.mrlc.gov/) should be considered the primary source for information
about current NLCD data products. The website includes reports, journal articles, and
conference articles and abstracts that document product types, methods for generating the
products, coverage, update cycles, and other product specifics. All data types (land cover,
percent impervious, and percent tree canopy) are not available for all years and all locations.
Users are reminded to refer to Section 1.3 for EPA's recommendations for processing NLCD
products with AERSURFACE based on data availability.
2.3 Assignment of Surface Characteristics by Land Cover Category
Each of the land cover categories in the two classification systems is mapped within
AERSURFACE to a set of seasonal values of albedo, surface roughness length, and Bowen
ratio. However, there are categories for which one or more of these surface characteristics
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cannot be adequately represented by a single seasonal value due to the climate of the area or
the physical setting and broader use of the area, such as if the location is an airport. This
section addresses the assignments of seasonal values and the special cases that are considered.
The seasonal values to the surface characteristics, by land use category, are provided in
Section 6.0.
2.3.1 Seasonal Values
The values of the surface characteristics, by land cover category, were developed for
five seasonal categories. The seasonal categories and the default months that comprise each
season are listed in Table 2-3. These seasonal categories are the same as those used by the
AERMOD model (EPA, 2024b) for the gas deposition algorithms (GDSEASON keyword).
When seasonal surface values are generated for input to AERMET, default monthly
assignments will be used. For monthly and annual values, the user is given the option of
assigning the individual months to a seasonal category that is appropriate for the climate and
conditions at the specific location. This option will allow a more locally appropriate estimate
that is more reflective of the area. Otherwise, the user can select to use the program's default
setting which assigns the months of March, April, and May to "Transitional spring with partial
green coverage or short annuals;" June, July, and August to "Midsummer with lush
vegetation;" and September, October, and November "Autumn with unharvested cropland."
The user can indicate whether the area experiences continuous snow cover in the winter. If the
area experiences periods of continuous snow cover during the winter, then the months of
December, January, and February are assigned to "Winter with continuous snow on ground."
If the area does not experience continuous snow cover, then the months of December, January,
and February will be paired with surface characteristic values listed "Late autumn after frost
and harvest, or winter with no snow." The user can opt to redefine the month-to-season
assignments and separately identify which months experience continuous snow cover and
those that do not. Further details regarding these user options are provided in Section 3.0.
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Table 2-3. AERSURFACE Season Definitions
Season Description
Default Month
Assignments
Midsummer with lush vegetation
Jun, Jul, Aug
Autumn with unharvested cropland
Sep, Oct, Nov
Late autumn after frost and harvest, or winter with no snow
Dec, Jan, Feb
Winter with continuous snow on the ground
Dec, Jan, Feb
Transitional spring with partial green coverage or short annuals
Mar, Apr, May
2.3.2 Surface Roughness Adjustments by Sector
In both the original 1992 and annual NLCD classification systems, there are categories
that are more broadly defined and can have a mix of land cover that make it difficult to assign
surface roughness values. More specifically, these are category 23,
Commercial/Industrial/Transportation, in the original 1992 NLCD and categories 21-24 in the
Developed class of the annual NLCD which include the Open Space, Low Intensity, Medium
Intensity, and High Intensity categories, respectively. Surface roughness value assignments are
more challenging in the annual NLCD since there is less specificity in the differentiation of the
four Developed categories referenced above. They are made up of a more diverse mix of land
cover types than the original 1992 NLCD Commercial/Industrial/Transportation category. The
Developed categories in the annual NLCD are defined based on types and percentages of
residences, vegetation (trees and grass), parks, roadways, runways, and industrial parks. The
main distinction between these categories is the difference in the amount of vegetation and
impervious surfaces, but the category definitions do not give much insight as to the types of
impervious surfaces or the types of vegetation.
Additionally, in the annual NLCD, three categories in the original 1992 NLCD that
delineated between Row Crops, Small Grains, and Fallow (categories 82-84 respectively),
which can have different roughness values based on type and season, have been condensed
into the single category of Cultivated Crops (82) in the annual NLCD classification scheme.
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Thus, this simplification in the more recent classification scheme represents a loss of
information helpful to determining roughness.
As a refinement, when available, AERSURFACE can now read and apply the percent
impervious and percent tree canopy values to these annual NLCD "Developed" categories.
When the land cover is supplemented with these data, the assigned values of surface roughness
are weighted based on the amount of the grid cell that is impervious vs. covered with a tree
canopy. This method of weighting the surface roughness is discussed in more detail below in
Section 2.4.1.
Surface roughness values can be calculated and adjusted for user-defined wind sectors.
Previous versions of AERSURFACE adjusted surface roughness values by defining a location
or sector as "airport" or "non-airport". As described above, some sectors that are
predominately made up of one or more categories that are ambiguous in their description may
have a makeup that is more typical of an "airport" while others may not. If the site is described
as an "airport", AERSURFACE will use surface characteristics that reflect an area dominated
by transportation type land cover such as roadways, parking lots, and runways. For "non-
airport" descriptions, AERSURFACE will choose higher surface roughness values that are
more representative of an area dominated by buildings associated with commercial and
industrial sites. Like the original 1992 NLCD, AERSURFACE assumes "airports" have lower
roughness due to the presence of roads, runways, and other paved surfaces while "non-airport"
descriptions are assumed to have higher roughness due to the presence of more buildings (i.e.,
lesser coverage of hard smooth surfaces at ground-level). As for vegetation, there is generally
more grassy areas, common between the runways, than trees.
In rural areas, surface roughness adjustments can be made to sectors that are
predominantly cultivated land to inform AERSURFACE to use roughness values that
represent higher roughness if land cover is predominantly row crops and lower roughness if
predominantly small grains or fallow. This reasoning has also been extended to the
Pasture/Hay category (81) to delineate between higher roughness (tall grasses and hays) and
lower roughness (short grasses).
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Beginning with the draft version 19039 DRFT and carried forward in version 20060,
individual sectors can be identified as either "airport" or "non-airport" sectors to more
accurately represent the makeup of those sectors (e.g., a "Developed" category that is
predominately made up of airport runways or paved lots vs buildings or structures). A sector
can be identified as "airport" or "non-airport" independently of whether the meteorological
tower is physically located at an airport and should be judged by the predominant land use
within a kilometer radius of the meteorological tower, giving more weight to land use nearest
the tower. Beginning with AERSURFACE version 24142, site and sector surface roughness
values for categories described in this section may be described with the former "airport" or
"non-airport" designation but may also be described with "lowzO" or "highzO " Use of these
designations are described in sections 3.2.9 and 3.2.10.
2.3.3 Climate
Albedo, Bowen ratio, and roughness length can each be influenced differently for
certain land cover categories based on if the region typically experiences arid conditions. The
land cover categories that are differentiated based on arid vs non-arid conditions are those
associated with the Barren, Shrubland, and Planted/Cultivated classes in the original 1992
NLCD and annual NLCD classification systems. In general, the albedo and Bowen ratio will
be higher and the surface roughness lower for arid regions than for non-arid regions. Note: If
the user specifies that the location experiences continuous snow cover for at least one
month during the year, AERSURFACE assumes that the area is non-arid.
In addition, different values are assigned to Bowen ratio based on surface moisture due
to precipitation and whether the site has experienced wetter than normal, dryer than normal, or
average (normal) conditions, in general. The surface moisture condition for the site may vary
depending on the meteorological data period for which the surface characteristics will be
applied. AERSURFACE applies the surface moisture condition for the entire data period.
Therefore, if the surface moisture condition varies significantly across the data period, then
AERSURFACE may need to be applied multiple times to account for those variations. The
surface moisture condition can be determined by comparing precipitation for the period of data
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to be processed to the 30-year climatological record. It is recommended the user specify "wet"
conditions if precipitation is in the upper 30th-percentile, "dry" conditions if precipitation is in
the lower 30th-percentile, and "average" conditions if precipitation is in the middle 40th-
percentile. However, the reader should consider that what is normal varies for different
regions. A dry (or wet) climate could be more normal for an area, so even if the amount of
precipitation is normal for a time period, the area might be more appropriately classified as
"dry" (or "wet"). In these cases, the user should justify their categorization.
2.4 AERSURFACE Calculation Methods
Determining effective surface characteristics for processing meteorological data for use
with the AERMOD model presents challenges. AERMOD is a steady-state plume model
which assumes spatially uniform meteorological conditions across the modeling domain for
each hour of meteorology, while land cover across the domain is typically very heterogeneous.
A sound understanding of the important physical processes represented in the AERMOD
model algorithms (Cimorelli, et al., 2004) and the sensitivity of those algorithms to surface
characteristics is needed to properly interpret the available data and make an appropriate
determination.
The recommendations for determining surface characteristics are presented in the
AERMOD Implementation Guide (EPA, 2024c) and have been incorporated into
AERSURFACE. These recommendations are summarized below, along with some additional
options that are included for evaluation and feedback, to refine the methods currently used and
extend the use of AERSURFACE with more recent land cover data (e.g., annual NLCD 1985-
2023).
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2.4.1 Surface Roughness Length
Based on model formulations and model sensitivities, the relationship between the
surface roughness upwind of the measurement site and the measured wind speeds is generally
the most important consideration. The surface roughness length should be based on an upwind
distance from the measurement site that captures the net influence of surface roughness
elements on the measured wind speeds needed to properly characterize the magnitude of
mechanical turbulence in the approach flow. Such changes in surface roughness result in the
development of an internal boundary layer (IBL) which grows with distance downwind of the
roughness change, and defines the layer influenced by the roughness elements.
The default method in AERSURFACE calculates surface roughness length as an
inverse distance weighted geometric mean, based on the land cover within the area around the
meteorological tower out to a default fixed radial distance of a 1 kilometer (km) from the
tower. Refer to the AERMOD Implementation Guide (EPA, 2024c) for a more detailed
discussion of the selection of the default value of 1 km as it relates to growth of the IBL
relative to the location and height of the wind measurements, as well as conditions for possible
exceptions to this default distance. Beginning with version 19039 DRFT and carried forward
in 20060 and 24142, this method is referred to as the "ZORAD" (fixed radius) option for
estimating surface roughness length in AERSURFACE and is considered the program default.
Also, beginning with version 20060 and carried forward in 24142, a research grade method,
"ZOEFF" (effective roughness), was added that does not limit the upwind fetch to a fixed 1
km distance from the tower. Rather, the distance and resulting area over which the roughness
length is estimated is based on the estimated growth of the IBL from the land cover
encountered as the air flows toward the meteorological tower. The distance over which
roughness is determined is sector dependent.
Surface roughness length can be computed as a single value over the full circular area
around the tower or may be varied by multiple wind sectors based on variations in land cover
around the tower. Sector widths are limited to a minimum of 30 degrees for a maximum of 12
sectors for use in AERMET. A new the option has been added to generate roughness length
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values for 16 sectors, 22.5 degrees each, for comparison with a standard wind rose plot;
however, this option is for diagnostic purposes only and cannot be input into AERMET.
The two distinct methods for estimating surface roughness length, ZORAD and
ZOEFF, and the incorporation of impervious and tree canopy data are discussed in the next
sections. As mentioned previously, AERSURFACE can now incorporate percent impervious
and percent tree canopy data into the roughness calculation for several land cover categories in
the annual NLCD that have somewhat ambiguous or broad definitions. The method for
incorporating these data into the roughness calculations is independent of the roughness option
specified and will be discussed in a subsequent section.
2,4,1,1 ZORAD - Default Method for Determining Roughness Length
The default method for determining surface roughness length (ZORAD) in
AERSURFACE is based on an inverse distance-weighted geometric mean. The mean is
calculated from the roughness values associated with the land cover category that defines each
land cover grid cell within the area or individual sectors out to a fixed radial distance from the
meteorological tower. The recommended and default radial distance as previously stated is
1 km.
The roughness values associated with each grid cell are weighted based on the inverse
distance from the meteorological tower. This is due in part to the fact that the width of a sector
increases with distance from the measurement site, such that there are more grid cells included
as the distance from the tower increases. Without including an inverse-distance weighting, the
land cover farther from the site would receive a higher effective weight than land cover closest
to the site if a direct area-weighted averaging approach were used. In addition, a geometric
mean is recommended for calculating the surface roughness length due to the fact that the
AERMOD formulations are dependent on the natural log (In) of the roughness length. The
arithmetic average of the natural log of the roughness length is mathematically equivalent to
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the geometric mean of the roughness length. The inverse distance-weighted geometric mean
roughness ( Zo ) is computed as follows:
where: n is the total number of grid cells over which the geometric mean is computed, i is one
of n grid cells, d is the distance between the center of the grid cell and the meteorological
tower,/? is 1, and Zo is the surface roughness length for individual grid cell i.
Individual monthly mean roughness values are computed separately for each sector.
Annual or seasonal values are then computed from the monthly values as simple arithmetic
means for each sector based on the temporal frequency of values specified by the user in the
control file. The input requirements for the ZORAD option are provided in Section 3.2.
2.4,1,2 ZOEFF - Experimental Method for Determining Roughness Length
A research grade method (ZOEFF) for determining the effective surface roughness
length for the tower location has been added to AERSURFACE. The ZOEFF option is based
on the calculated growth of the internal boundary layer (IBL) as roughness elements are
encountered approaching the meteorological tower. Rather than computing the average
roughness over a default 1 km distance, the ZOEFF method estimates the distance required for
IBL growth to a certain predefined height defined as some multiple of the wind measurement
height. The fetch is computed separately for each month and sector. Monthly values of the
effective roughness length are then computed separately for each sector based on the derived
sector-specific fetch. The input requirements for the ZOEFF option are provided in Section
3.2 and a technical description of the ZOEFF method and its implementation in AERMOD is
presented in Section 9.0 (Appendix E).
1
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As with the ZORAD method, individual roughness values are computed separately for
each month and sector. Annual or seasonal values are then computed from the monthly values
as simple arithmetic means for each sector based on the temporal frequency of values
specified by the user in the control file.
2,4,1,3 Supplemental Percent Impervious and Canopy Data
Regardless which method is specified for determining roughness length, ZORAD or
ZOEFF, annual land cover data can be supplemented with percent impervious and percent tree
canopy data, when available. These data products report the percent (0-100) of each grid cell
that is covered by an impervious surface and the percent (0-100) covered by tree canopy,
respectively. The percent impervious surface and percent tree canopy for a given cell can sum
to less than 100 percent, but the sum should not exceed 100 percent. AERSURFACE checks
the total for each grid cell. If the total should exceed 100%, AERSURFACE normalizes the
individual percentages based on the total percentage reported so that they sum to 100 percent.
When impervious and canopy data are used to supplement land cover data, the
Developed categories (21, 22, 23 and 24) of the annual NLCDs are adjusted based on values
assigned to original 1992 NLCD categories that better define land use. The Developed
categories are reassigned as a mix of the original 1992 categories that make up High Intensity
Residential (22), Bare Rock/Sand/Clay (31), Mixed Forest (43), and Urban/Recreational
Grasses (85). Low z0 (airport)sectors assume a majority of the impervious area is bare
rock/sand/clay to represent the runways, while high z0 (non-airport) sectors assume a majority
of the impervious area is more similar to the original 1992 category High Intensity Residential
to account for a greater percentage of buildings. The Mixed Forest portion is further weighted
based on the percent of the area that is tree canopy while the Bare Rock/Sand/Clay and High
Intensity Residential categories are weighted based on the percent of the grid cell that is
impervious. The Urban/Recreational Grasses portion is weighted based on the amount that is
neither impervious nor tree canopy. As mentioned previously, a substantial percent of the
impervious surfaces for some portion of an airport will be runways, which are not present at
non-airport sites. A substantial amount of the vegetation at an airport is grass between and
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around the runways, rather than trees. Reassigning the annual NLCD Developed categories
with weighted values from the original 1992 NLCD classification is an attempt to better
estimate the roughness for a given grid cell where the category description is not specific to
the type of impervious surface or vegetation. NOTE: Beginning with AERSURFACE v20060,
users now have the option to separately characterize individual wind sectors as "airport" or
"non-airport" based on the predominant land use within each sector (refer to Sections 3.2.9,
and 3.2.10). Since these characterizations may be made outside of an airport location
AERSURFACE version 24142 has replaced the "airport" and "non-airport" descriptors with
"low z0" and "high z0" respectively. A decision tree for the annual NLCD Developed
categories, as implemented in AERSURFACE, is provided in Figure 2-1 that demonstrates
how the surface roughness values are reassigned for an individual grid cell using the
impervious and canopy data.
Similarly, surface roughness length for the annual NLCD Woody Wetlands category
(91) is redefined as a mixture of: Woody Wetlands (91), weighted by the fraction of the grid
cell that is tree canopy; Bare Rock/Sand/Clay (31), weighted by the fraction of the cell that is
impervious; and the original 1992 category Urban/Recreational Grasses (85), weighted by the
fraction of the grid cell that is neither canopy nor impervious. Whether or not the sector is
identified as "low z0" (airport), or "high z0" (non-airport) is not considered in this case.
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Land Cover Supplemented with
Impervious and Canopy Data?
Yes
Airport
Sector?
Yes
No
No
Use AERSURFACE Roughness Table
Recategorize as Combination of:
• Mixed Forest (43) x %Canopy/100
• 90%: 1992 High Intensity Residential (22) x %lmpervious/100
10%: Bare Rock/Sand/Clay (31) x %lmpervious/100
1992 Urban Recreational Grasses (85) x (1.0 - %Canopy/100- %lmpervious/100)
Ex. Developed-Medium Intensity (23): summer, 60% impervious, 10% canopy
zq = exp( ln(1.3)*0.1 + 0.9*ln(1.0)*0.6 + 0.1*ln(0.05)*0.6 + ln(0.02)*0.3 ) = 0.27
Recategorize as Combination of:
• Mixed Forest (43) x %Canopy/100
10%: 1992 High Intensity Residential (22) x %lmpervious/100
90%: Bare Rock/Sand/Clay (31) x %lmpervious/100
1992 Urban Recreational Grasses (85) x (1.0 - %Canopy/100- %lmpervious/100)
Ex. Developed-Medium Intensity (23): summer, 60% impervious, 10% canopy
z0 = exp( ln(1.3)*0.1 + 0.1*ln(1.0)*0.6 + 0.9*ln(0.05)*0.6 + ln(0.02)*0.3 ) = 0.06
Figure 2-1. Surface Roughness Value Adjustment to Annual NLCD Developed Categories (21-24)
Using Percent Impervious and Canopy Data.
2.4.2 Daytime Bowen Ratio
Bowen ratio is calculated as the simple geometric mean of the Bowen ratio values of
the individual grid cells that make up the 10 km x 10 km area centered on the measurement
site. The Bowen ratio is an unweighted value in the sense that there is no distance or
directional dependency in the calculation. Each grid cell in the 10 km x 10 km area is given
equal weight in the calculation of the mean value over. The simple, unweighted geometric
mean Bowen ratio ( B ) is calculated using the following equation:
B = exp
'!?= i ln(Bty
n
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where: n is the total number of grid cells over which the geometric mean is computed, i is one
of n grid cells, Bi is the Bowen ratio for the individual grid cell i.
Individual monthly mean Bowen ratio values are computed. Annual or seasonal values
are then computed from the monthly values as simple arithmetic means based on the temporal
frequency of values specified by the user in the control file.
2.4.3 Noontime Albedo
Albedo is calculated as the simple arithmetic mean, also unweighted (i.e., no direction
or distance dependency), for the same 10 km by 10 km area defined for Bowen ratio. The
simple arithmetic mean albedo (a) is calculated using the following equation:
_ ,
a = -J
n
where: n is the total number of grid cells over which the geometric mean is computed, i is one
of n grid cells, m is the albedo for the individual grid cell i.
Individual monthly mean albedo values are computed. Annual or seasonal values are
then computed from the monthly values as simple arithmetic means based on the temporal
frequency of values specified by the user in the control file.
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3.0 Detailed keyword reference
AERSURFACE has been updated to read an ASCII text input control file that makes use
of the path/keyword approach, to inform AERSURFACE of user options, similar to AERMOD,
AERMET, and AERMAP. This section provides a detailed description of the keywords and
related parameters, their use, and the format of the control file.
3.1 Overview
The descriptive keywords and parameters that make up the control file informs
AERSURFACE of the user-defined options and parameters to apply during processing. These
include specific processing options, control values, and input/output directory paths and
filenames. Each line of the control file consists of a 2-character pathway ID, a primary keyword,
and a parameter list. 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 or
input data that will be used during processing. Some of the parameters are also input as
descriptive secondary keywords.
3.1.1 Pathway IDs
The AERSURFACE control file is divided into two functional "pathways." The pathways
IDs and the order in which they should appear in the control is as follows:
• CO - for specifying overall job COntrol options; and
• OU - for specifying OUtput options.
The pathway ID must be present on the first and last input lines of the ID block of text
but may be omitted on the lines in between. However, the primary keyword that would follow
the pathway ID must begin in column 4 of the control file. An example control is provided in
Section 3.4.
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3.1.2 Starting and ending a Pathway Block
Regarding the format of a control file, a basic rule is that all inputs for a particular
pathway must be contiguous within a block of text, i.e., all inputs for the CO pathway must come
first, followed by the inputs for the OU pathway. 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 control file must be "CO STARTING," followed by the
separate lines for each primary keyword and related parameter list. The CO pathway is then
ended with "CO FINISHED" and, subsequently, the OU pathway is started with "OU
STARTING," and the last functional record of each control file must be "OU FINISHED" which
ends the OU pathway. As shown in the example control file in Section 3.4, the pathway ID (e.g.,
CO and OU) do not need to be included on every record except the first and last records of the
pathway. This is to improve the readability of the control file. The pathway ID does not have to
be omitted; however, on those records where the pathway ID is omitted, the primary keyword
must begin in column 4, and columns 1 through 3 should be filled with blank spaces.
3.1.3 Blank Lines and Comments
Two special provisions to increase flexibility in the structuring of the control file include:
allowing blank records to separate input data for readability and comment lines that enable the
user to annotate the control file. Comment lines are identified with two asterisks ("**") in the
pathway field (i.e., first two columns of a line). Any input image that has "**" for the pathway
ID will be ignored. While comment lines are useful for including descriptions in the control file,
it may also be used to "comment out" certain options for a run without deleting the options and
associated data completely from the input file.
The information in the remainder of this section is organized by pathway ID and function,
i.e., the keywords are grouped by pathway. The syntax for each keyword is provided, and the
keyword type is specified as mandatory, optional, or conditional and either repeatable or non-
repeatable. Unless noted otherwise, there are no special requirements for the order of keywords
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within each pathway. 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. Primary
keywords are in all capital letters (may also contain numbers). Primary keywords are not
underlined. 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 italicized. 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.
3.2 Control Pathway (CO)
The CO pathway contains the keywords that provide the overall control of the
preprocessor run. The CO pathway must be the first pathway in the control file.
3.2.1 Title information (TITLEONE. TITLETWO)
There are two keywords that allow the user to specify up to two lines of title information.
The title is included as comment cards in the output data file. 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
Type:
TITLEONE - Mandatory, Non-repeatable
TITLETWO - Optional, Non-repeatable
The parameters title2 and title2 are character parameters of length 200, which are read as a
single field from columns 13 to 200 of the input record.
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3.2.2 Options (OPTIONS^)
The OPTIONS keyword is not required but can be included to specify non-default
options. The options available and usage is shown below:
Syntax:
CO OPTIONS PRIMARY
ZORAD
or
or
SECONDARY
ZOEFF
Type:
Optional, Non-repeatable
The PRIMARY and SECONDARY options inform AERSURFACE whether the site processed is
the primary or secondary location. This determines which keywords to include in the output file
that contains the surface characteristic values and that are input directly into AERMET.
AERMET can require up to two sets of surface characteristic values (primary and secondary),
depending on the meteorological data that are processed. A set of surface characteristic values
for the primary meteorological site is always required. The primary site is the location of the
National Weather Service (NWS)/Federal Aviation Administration (FAA) weather station if only
NWS/FAA surface data collected at an airport are processed. When site-specific meteorological
data are processed, the primary location is the site-specific meteorological tower. AERMET can
substitute missing site-specific wind data with NWS/FAA data if NWS/FAA data are provided as
input. In that case, AERMET requires a set of secondary surface characteristic values for the
location of NWS/FAA met tower. The primary set of surface characteristics are defined for
AERMET through the three keywords FREQ SECT, SECTOR and SITE CHAR used to specify
the temporal frequency, number of sectors, and the site characteristics (albedo, Bowen ratio, and
surface roughness length), respectively. The secondary set of site characteristics are specified
using similar keywords, FREQ SECT2, SECTOR2, and SITE CHAR2. AERSURFACE can
only process a single site at a time and will need to be run twice when site-specific
meteorological data are to be processed with AERMET and NWS/FAA data will be used to
substitute missing wind data. (Refer to the AERMET User's Guide (EPA, 2024a) for more
information on processing site-specific meteorological data and data substitution using
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concurrent NWS/FAA surface data.) AERSURFACE will generate the required AERMET
keywords for the primary site by default if the OPTIONS keyword is not included in the CO
pathway or if PRIMARY or SECONDARY is not included with the OPTIONS keyword.
The ZORAD and ZOEFF options inform AERSURFACE of the method to use to calculate
surface roughness length. ZORAD is the default method used in previous versions and described
above. This method calculates the average roughness from the meteorological tower out to a
default radial distance of 1 km. ZOEFF is a research grade method that estimates fetch based the
growth of the IBL due to changes in roughness downwind. Average roughness is computed over
the estimated fetch, approaching the meteorological tower. Roughness length can be calculated
for individual user-defined wind sectors using either method. When ZOEFF is specified, the
fetch over which the roughness is calculated is estimated separately for each wind sector
specified.
3.2.3 Debug Options (DEBUGOPT^
AERSURFACE provides several debug options using the DEBUGOPT keyword which
will generate various output files that contain different types of diagnostic information. The
syntax for the DEBUGOPT keyword and the different options are summarized below:
Syntax: CO DEBUGOPT EFFRAD and/or GRID and/or TIFF or ALL
Type: Optional, Non-repeatable
The order of the secondary keywords is not important. A description the output file that each
option will generate follows:
EFFRAD: File containing the effective radius for surface roughness computed for each
sector/month (only applicable for ZOEFF option specified with the
OPTIONS keyword).
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GRID: Separate grid file of land cover data and, if applicable, impervious, and
canopy data, displaying the 10x10 km grid of values extracted from each
GeoTIFF data file.
TIFF: Separate file for each GeoTIFF data file containing a list of all TIFF tags,
GeoKeys, and associated values read from the file.
ALL: This option can be used to inform AERSURFACE to generate all debug
files listed above without having to list each debug option separately.
Each file generated from the debug options has a default filename. Default filenames can be
overridden with user-defined filenames using file-specific keywords on the OU pathway (refer to
Section 3.3). AERSURFACE automatically generates a log file that includes a summary of TIFF
parameters, land cover counts by category for each sector for surface roughness and land cover
counts by category for the 10km x 10km domain used for Bowen Ratio and Albedo. The log file
also includes tables of final calculated roughness values and the fetch used, by month and sector,
to compute the roughness.
3.2.4 Location of Meteorological Tower (CENTERXY. CENTERLL)
The location of the meteorological tower where representative values of the surface
characteristics will be calculated can be specified using either the Universal Transverse Mercator
(UTM) coordinate system or latitude and longitude. UTM coordinates are entered using the
CENTERXY keyword while latitude and longitude are entered using the CENTERLL keyword.
The syntax and required parameters are discussed below:
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Syntax: CO CENTERXY easting northing utm zone datum
or
CO CENTERLL latitude longitude datum
Type: Mandatory, Non-repeatable
where:
UTM easting coordinate in meters.
UTM northing coordinate in meters.
UTM zone entered as a positive integer.
Latitude in decimal degrees. (Northern hemisphere = positive value)
Longitude in decimal degrees. (Western hemisphere = negative value)
Geodetic datum on which coordinates are based. The datum should be
entered using one of the following secondary keywords: NAD27 or NAD83.
which refer to the North American 1927 datum and the North American
1983 datum, respectively. NAD83 should also be used for coordinates
referenced to the WGS84 ellipsoid since the small differences between
NAD83 (which uses the GRS80 ellipsoid) and WGS84 are inconsequential
for the purposes of AERSURFACE. See note immediately below when
processing locations in Hawaii and Puerto Rico.
NOTE: Included with the AERSURFACE executable file are NAD Grid conversion files
(conus.los and conus.las) for converting coordinates between North American Datums
NAD27 and NAD83 for the CONUS and Alaska. Earlier versions of AERSURFACE that
processed only the original 1992 NLCD allowed the user to specify coordinates referenced
to either the NAD27 datum or NAD83 and AERSURFACE would convert user coordinates
or coordinates derived from the NLCD file to be consistent. This capability has been
easting:
northing:
utm zone:
latitude:
longitude:
datum:
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carried forward for the CONUS and also works for Alaska. When conversion is needed
between NAD27 and NAD83 for the CONUS or Alaska, the NAD Grid conversions files
(e.g., conus.las, conus.los, alaska.las, alaska.los) provided with the AERSURFACE
executable (aersurface.exe) need to be stored in the directory with the executable. However,
AERSURFACE has not been extended to make similar conversions for older datums
specific to Hawaii and Puerto Rico. When running AERSURFACE for locations in Hawaii
and Puerto Rico, the coordinates entered by the user should be referenced to the NAD83
datum or the WGS84 ellipsoid, and NAD83 should be specified as the datum entered in the
AERSURFACE control file. AERSURFACE treats NAD83 and WGS84 identically (NLCD
files from the MRLC Consortium website are referenced to either NAD83 or WGS84,
depending on the product.)
3.2.5 NLCD Filenames (DATAFILE^
NLCD data filenames, including the names of impervious and canopy files when used to
supplement land cover data, are specified using the DATAFILE keyword. The keyword is
repeatable so that multiple file types can be specified when more than one type of data will be
processed. At a minimum, a land cover file is required. At most, three files can be processed
including a single land cover file, a single impervious file, and a single canopy file. The syntax
and type of the keyword are summarized below:
Syntax: CO DATAFILE datajype pathJilename
Type: Mandatory, Repeatable
The data type is entered using a secondary keyword to represent the type of data and year the
data represent. The data type must be an 8-digit alphanumeric input starting with the 4-digit data
type abbreviation, followed by the 4-digit year, with no spaces. The data type abbreviations
include: NLCD for land cover, MPRVfor impervious, and CNPY for canopy data.
AERSURFACE will now accept all NLCD release years available for download from the
MRLC. However, users should note that this version of AERSURFACE cannot process the
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newly available pre-1993 NLCD years (i.e., 1985 to 1992) if the corresponding 4-digit year (e.g.,
"NLCD1985", "NLCD 1992", etc.) is used due to differences in the land cover classification
system used in the latest edition of these NLCD years and those hard coded in AERSURFACE.
Users should use the 1993 DATAFILE keyword (i.e., "NLCD1993") to process annual NLCD
for years 1985 to 1992. If processing an older edition of the 1992 NLCD, the 1992 DATAFILE
keyword (i.e., "NLCD1992") should be used to ensure this data is processed using the 1992
NLCD classification scheme with 21 classes. If more than one file is input, all must have the
same year. Be sure to clearly document in the input control file the representative NLCD year
and edition that is processed (i.e., newly released annual NLCD or legacy NLCD). The following
are examples of secondary keywords for data type:
NLCD2021: 2021 NLCD land cover
MPRV2021: 2021 percent impervious
CNPY2021: 2021 percent canopy
The path Jilename can be entered using either the relative or absolute path. The relative path is
relative to the working directory. Enter the pathJilename using the syntax that is appropriate for
the operating system on which AERSURFACE is run. For example, when running under the
Microsoft Windows command prompt, the path and filename are not case-sensitive, but directory
names should be separated with a "\" rather than a "/". Conversely, the path and filename are
case-sensitive on Unix/Linux systems and directory names should be separated with a
Regardless, the operating system, a path and filename that includes spaces should be wrapped in
double quotes (""). The combined path and filename is limited to a maximum of 200 characters
in AERSURFACE.
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3.2.6 Fixed Radial Distance for Roughness (ZORADIUS)
When the default method (ZORAD) is used to calculate the surface roughness length, the
default radial length of 1 km, the distance over which the roughness length is averaged from the
tower, can be overridden by the user using the ZORADIUS keyword. This keyword is only
applicable when ZORAD is included with the OPTIONS keyword or both ZORAD and ZOEFF
are omitted in which case, ZORAD is the default method. The syntax for the ZORADIUS
keyword is as follows:
Syntax:
CO ZORADIUS radius
Type:
Optional, Non-repeatable
where radius is the distance from the meteorological tower in kilometers over which the effective
surface roughness will be computed. The valid range for the user-defined radius is 0.5 km to 5.0
km; however, any distance other than the 1 km default radius may require justification and
should be discussed with the reviewing agency. If the ZORADIUS keyword is omitted, the
recommended default radius of 1.0 km will be used.
3.2.7 Anemometer Height (ANEM HGT)
When the method ZOEFF is used to calculate the surface roughness length, the
ANEMHGT keyword is required to specify the height of the anemometer is required. The
syntax and parameters associated with the ANEM HGT keyword is summarized below:
Syntax: CO ANEM HGT anem ht (iblJactor)
Type: Mandatory, Non-repeatable
where anem Jit is the height, in meters, at which the wind measurements are taken at the site that
will be processed. The accepted value for anem Jit ranges from 1.0 meter to 100.0 meters.
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The iblJactor is an optional unitless parameter, ranging from 5.0 - 10.0, used to compute
the reference height of the IBL at the location of the meteorological tower. The IBL reference
height is the product of the anemjit and the iblJactor. The default value for ibl Jactor is 6.0
based on Wieringa's suggested 60 m "roughness blending height" (Wieringa, 1976) and given
that 10 m is a common anemometer height at NWS/FAA meteorological stations. Refer to
Section 9.0 (Appendix E) for more information on the implementation of the ZOEFF method in
AERSURFACE.
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3.2.8 Climate. Surface Moisture, and Continuous Snow Cover (CLIMATE)
As previously discussed in Section 2.4, the surface characteristic values calculated by
AERSURFACE can vary based on local climate and surface moisture conditions, including
whether the site experienced extended periods of continuous snow cover. The CLIMATE
keyword is used to inform AERSURFACE of this information. This is an optional keyword for
which default entries will be assumed if the CLIMATE keyword is omitted. The syntax for the
CLIMATE keyword and related parameters is summarized below:
Syntax: CO CLIMATE sfc moisture snow cover arid condition
Type: Optional, Non-repeatable
where sfc moisture refers to the surface moisture based on precipitation amounts for the period
that will be modeled, relative to the previous 30-year climatological record for the region;
snow cover indicates whether the site experienced one or more extended periods of continuous
snow cover; and arid condition defines the typical climate of the region as arid such as desert-
like or non-arid.
sfc moisture should be entered as either WET. DRY, or AVERAGE (or AVG) where, in
general, WET is defined as precipitation amounts equal to or greater than the 70th percentile of
the 30-year climatological records; DRY is equal to or less than the 30th percentile; and
AVERAGE is between the 30th and 70th percentiles. However, as previously discussed, the
reader should consider that what is normal varies for different regions. A dry (or wet) climate
could be more normal for an area, so even if the amount of precipitation is normal for a time
period, the area might be more appropriately classified as "dry" (or "wet"). In these cases, the
user should justify their categorization. If omitted, AERSURFACE assumes an AVERAGE
default surface moisture. A recommended approach is to determine moisture conditions either
seasonally or monthly, then run AERSURFACE separately for each condition and use the results
to compile a single input file for AERMET that contains the appropriate seasonal or monthly
surface characteristic values.
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Whether the site experienced periods of continuous snow cover during the winter should
be specified using either the SNOW or NOSNOW secondary keywords. If omitted,
AERSURFACE assumes a default of NOSNOW. meaning there were no winter months that
experienced periods of continuous snow cover. Continuous snow cover is defined as a calendar
month during which the ground was covered with snow more than 50% of the time. If the
secondary keyword SNOW, is specified, then AERSURFACE will treat all winter months
assigned to "Winter with continuous snow on the ground," as having continuous snow cover.
The user has the option to use the default month-to-season assignments or to reassign months to
each of the five seasons recognized by AERSURFACE, listed in Table 2-3, using the SEASON
keyword discussed in Section 3.2.11, below. If default assignments are used, then all winter
months will be treated as either having continuous snow or having no snow. The default winter
months, per Table 2-3, are December, January, and February.
The last parameter associated with the CLIMATE keyword, arid condition, is only
applicable if NOSNOW was entered for snow cover and should be specified using the secondary
keyword ARID or NONARID where ARID refers to a desert-like climate. The default condition
is NONARID when the CLIMATE keyword is omitted. AERSURFACE also assumes
NONARID if any month experiences continuous snow cover. Note: AERSURFACE will abort
processing and report an error if the secondary keywords SNOW and ARID are used in
combination with each other.
To summarize, if the CLIMATE keyword is omitted from the control file,
AERSURFACE assumes the following settings by default: AVERAGE. NOSNOW. and
NONARID.
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3.2.9 Temporal Frequency (FREQ SECT)
Surface characteristics should reflect how they change temporally for a location.
Depending on the climatology and land cover, there may be little change throughout the year, or
there may be large changes on a seasonal or even monthly basis. The FREQSECT keyword
defines time period over which the surface characteristics will be computed. This keyword is also
used to specify the number of wind sectors that will be defined when determining roughness
length and whether adjustments will be made to sector roughness values (e.g., "lowz0"/ "airport"
or "highzo'7 "non-airport"). The syntax and usage of the mandatory FREQ SECT keyword is
summarized below:
Syntax: CO FREQ SECT frequency number sectors roughness flag
Type: Mandatory, Non-repeatable
where frequency is the period of time for which the surface characteristics are calculated which
include ANNUAL. SEASONAL, or MONTHLY. When ANNUAL or MONTHLY is entered,
the user has the option to override program defaults and reassign months to seasons based on
local climatology. The default assignments, which are always used when SEASONAL is
specified, are as follows:
Table 3-1. Default Month/Season Assignments in AI RM I T
Season #
Season
Default Months
1
Winter*
December, January, February
2
Spring
March, April, May
3
Summer
June, July, August
4
Autumn
September, October, November
* Winter will either be defined as winter with continuous snow cover or winter with
without snow based on the option specified with the CLIMATE keyword, discussed
previously.
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The number sectors parameter should be entered as the integer number of wind sectors
that will later be defined using the SECTOR keyword. Wind sectors are only applicable to
roughness length. The number of sectors can range from 1 to 12 or 16. AERMET allows a
maximum of 12 sectors, but AERSURFACE can calculate roughness for 16 sectors which can be
useful for comparing roughness lengths to a standard 16-direction wind rose plot. When 16
sectors are specified, AERSURFACE results cannot used as input to AERMET.
The last parameter, roughness flag, requires a secondary keyword that determines
whether AERSURFACE will adjust roughness values to all wind sectors, or if the sectors vary.
The roughness Jlag should be specified using one of the following secondary keywords:
LOWZO. HIGHZO or VARYZO where: LOWZO indicates lower roughness values will be applied
to all sectors; HIGHZO indicates that higher roughness values will be applied; and VARYZO
informs AERSURFACE to treat each sector separately based on how the sector is identified
using the SECTOR keyword discussed next.
NOTE: In previous versions of AERSURFACE, this keyword was referred to as the
airport Jlag with AP. NONAP. and VARYAP options. These options are still available in
AERSURFACE v24142 and are defined as LOWZO. HIGHZO. and VARYZO. respectively.
Users may want to consider characterizing sectors at an airport for which the impervious surfaces
are predominantly buildings rather than paved surfaces or that are predominantly vegetation as
non-airport. Similarly, sectors at a measurement site that is not at an airport, but the impervious
surfaces are predominantly paved surfaces, can be characterized as airport. (Refer to Sections
2.3.2 for additional discussion on airport vs non-airport characterization of a measurement site or
individual sectors.)
3.2.10 Surface Roughness Length Wind Sectors (SECTOR)
Individual wind sectors for which roughness length is determined are defined using the
SECTOR keyword by specifying a starting and ending wind direction for each sector. As
mentioned above, the SECTOR keyword is also used to indicate whether lower or higher
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roughness values should be applied to individual sectors. The usage and syntax of the SECTOR
keyword are summarized below:
Syntax: CO SECTOR sector index start dir end dir roughness flag
Type: Conditional, Repeatable
While there are circumstances for which the SECTOR keyword is not required, when
included, the number of occurrences of the SECTOR keyword must match the number of sectors
{number sectors) specified with the FREQSECT keyword. The sector index links a specific
sector to a set of site characteristics and should be entered as consecutive integers beginning with
the number 1. As discussed, the number of sectors can range from 1 to 12 for input to AERMET,
and sectors must be a minimum of 30°. AERSURFACE can also generate surface characteristic
values for a discrete number of 16 sectors that are each 22.5° that may be useful for comparing
roughness length by sector to a standard 16-direction wind rose plot but cannot be used as input
to AERMET.
Sectors should be defined in a clockwise manner and must cover the full 360° circle
around the meteorological tower without gaps or overlap, (i.e., They must be defined so that the
end of one sector corresponds to the beginning of another.) The starting direction {start dir) is
considered part of the sector, while the ending direction {end dir) is excluded from the sector.
The starting and ending directions reference the wind direction, the direction from which the
wind is blowing. A sector can cross through north (e.g., 345 - 15) or can start and stop at north
(e.g., 0-30 and 270 - 360). AERSURFACE will verify that the entire 360° circle is covered.
The roughnessJlag (previously, airport Jlag) on the SECTOR keyword identifies
whether the individual sector should be processed with lower (airport) or higher (non-airport)
surface roughness length values. This attribute is required when the secondary keyword
VARYZ0 or VARYAP is entered as the roughnessJlag attribute for the FREQ SECT keyword
which means each sector will be assigned individually. When that is the case, the roughnessJlag
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should be specified using the secondary keyword LOWZO or AP to indicate lower roughness
values or HIGHZO or NONAP to indicate higher surface roughness values. (Refer to Sections
2.3.2 for additional discussion on airport vs non-airport characterization of a measurement site or
individual sectors.)
When 1, 8, 12 or 16 is entered for the number of sectors on the FREQSECT keyword,
the SECTOR keyword may be omitted, and default sectors can be used unless VARYZO is
entered as the roughnessJlag attribute for the FREQ SECT keyword. For those cases in which
1, 8, 12, or 16 sectors are specified, and the SECTOR keyword is omitted, AERSURFACE will,
by default, generate one 360-degree, eight 45-degree, twelve 30-degree, or sixteen 22.5-degree
sector(s), respectively. Eight sectors are centered on 0, 45, 90, etc. degrees. Twelve sectors are
centered on 15, 45, 75, etc. degrees. Sixteen sectors are centered on 0, 22.5, 45, etc. degrees.
When VARYZO is specified on the FREQ SECT keyword, the SECTOR keyword is required
and the roughness Jlag attribute is required for each sector, though the starting and ending
directions may be omitted if default directions are intended.
3.2.11 Assigning Months to Seasons (SEASON)
AERSURFACE provides the option to override default month-to-season assignments when the
temporal resolution for the surface characteristics, or the frequency attribute on the FREQSECT
keyword, is ANNUAL or MONTHLY. When the frequency is SEASONAL, the default
assignments are used, listed in
Table 3-1, above. This is to maintain consistency with AERMET and its seasonal
definitions. Calculating annual or monthly surface characteristic values and reassigning months
from the default season assignments provides for greater representativeness for those areas of the
country that do not experience the traditional seasons. The SEASON keyword is used to override
the default assignments. The usage and syntax of the SEASON keyword are summarized below:
Syntax: CO SEASON season months (space delimited list)
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Type: Optional, Repeatable
where season is a secondary keyword that identifies one of five seasonal definitions and months
is a space-delimited list of integer months assigned to the season. Valid secondary keywords
used to specify season, along with the season definition are listed in Table 3-2, below. Valid
entries for the attribute months are a "0" to indicate no months are being reassigned to the season
or a space-delimited list with each value ranging from 1 to 12 where 1 represents January and 12
represents December. A season may be specified only once. The months reassigned to a season
should be listed on a single record separated by at least one space. A month can only be assigned
to one season. It is only necessary to specify the seasons/months that are to be reassigned. If 0 is
entered for a season, then default assignments will be used for any month that is not listed for a
different season.
Table 3-2. Season Secondary Keywords and Definitions
Secondary
Keyword
Season Description
Default Month Assignments
SUMMER
Midsummer with lush vegetation
June, July, August
AUTUMN
Autumn with unharvested cropland
September, October, November
WINTERNS
Late autumn after frost and harvest, or
winter with no snow
December, January, February
WINTERWS
Winter with continuous snow on the
ground
December, January, February
SPRING
Transitional spring with partial green
coverage or short annuals
March, April, May
3 .2.12 To Run or Not (RUNORNOT)
Before beginning to read and process the datafiles, AERSURFACE will read through all
of the inputs in the control file regardless of any errors or warnings that may be encountered. If a
fatal error is encountered, then further program calculations will be aborted. Otherwise, the
program will attempt to run. The RUNORNOT keyword has been included on the CO pathway
to allow the user to specify whether to RUN the program and perform all the calculations, or
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only process the control file and check for warnings and errors and summarize the setup
information. The syntax of the RUNORNOT keyword is summarized below:
Syntax: CO RUNORNOT RUN or NOT
Type: Mandatory, Non-repeatable
3.3 Output Pathway (OU)
The OUtput pathway is used to specify user-defined filenames for program generated
output files that cannot be entered as an argument at the command prompt when AERSURFACE
is executed. Those that can be entered as a command-line argument include: 1) an input
summary file that replicates the control file inputs and includes a summary of warnings and
errors encountered during processing and 2) a log file that records more detailed information
about the input data that are read during program execution (see Section 3.0). The OU pathway is
required to be included in AERSURFACE input control file; however, all file-specific keywords
are optional. If the user prefers that default filenames are assigned, the OU pathway can be
empty with only the OU STARTING and OU FINISHED records specified and AERSURFACE
will used the default filenames shown in Table 3-3. All output files that can be specified in the
OU pathway are generated based on the debug options that are specified with the DEBUGOPT
keyword in the CO pathway (see Section 3.2.3) in combination with the types of data that are
used to derive the surface characteristic values specified with the DATAFILE keyword in the CO
pathway (i.e., land cover, percent impervious, and percent canopy). It preferable to specify user-
defined filenames rather than use default filenames to avoid unintentionally overwriting files
with the same name output from previous AERSURFACE runs.
3.3.1 Surface Characteristic Values File for AERMET (SFCCHAR)
As referenced above, the user can specify the name of the file that will contain the surface
characteristic values calculated by AERSURFACE that will be formatted input to AERMET. It
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is entered in the OU pathway with the SFCCHAR keyword. IF SFCCHAR is omitted from the
OU pathway, the default filename, sfc chars, out, will be assigned. The usage and syntax of
SFCCHAR keyword is summarized below:
Syntax:
OU SFCCHAR path Jilename
Type:
Optional, Non-repeatable
where pathJilename is the user-defined path and filename of the surface characteristics file. The
path can be entered as the absolute path or a relative path, relative to the working directory. If the
path is omitted, the file will be created in the working directory. The combined path and filename
is limited to 200 characters and should be enclosed in quotes ("") if either the path or filename
includes spaces.
3.3.2 Debug Output Files
There are several debug files that can be generated by AERSURFACE. A file's creation
is based on the debug options that are specified with the DEBUGOPT keyword in the CO
pathway (see Section 3.2.3) and the types of data that are input to AERSURFACE (i.e., land
cover, percent impervious, and percent canopy). The user has the option to enter a user-defined
path and filename for any of these debug files by specifying the primary keyword associated with
the debug file, followed by a path and filename. For any keyword and pathYfilename combination
that are omitted on OU pathway, AERSURFACE will use the default filename and create the file
in the working directory. There is a distinct primary keyword associated with each debug file.
The general usage and syntax for the keywords is summarized below and a list of the keywords
as well as the associated debug option, description, and default filename is provided in Table 3-3.
Note: Though the entry of any of the debug file keywords and associated path and
filenames are optional, each keyword that is specified must include an associated filename
and a filename must be preceded by the associated keyword.
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Syntax: OU primary keyword pathfilename
Type. Optional, Non-repeatable (each primary keyword in Table 3-3 can only be
used once)
where primary keyword is a primary keyword from Table 3-3 and pathfilename is the user-
defined path and filename of the output file. The path can be entered as the relative or absolute
path. A relative path is relative to the working directory. The combined path and filename are
limited to 200 characters and should be enclosed in quotes ("") if either the path or filename
includes spaces.
Table 3-3. OU Pathway Primary Keywords and Default Filenames
Keyword
DEBUGOPT
Description
Default Filename
SFCCHAR
Surface characteristic values formatted
for input to AERMET
sfcchars.out
EFFRAD
EFFRAD
Table of effective radius values by
sector and month
effective_rad.txt
NLCDGRID
GRID
Land cover grid for import into GIS
landcover.txt
MPRVGRID
GRID
Impervious data grid for import into
GIS
impervious.txt
CNPYGRID
GRID
Canopy data grid for import into GIS
canopy.txt
NLCDTIFF
TIFF
Land cover debug file containing TIFF
tag and GeoKey values
lc_tif_dbg.txt
MPRVTIFF
TIFF
Impervious debug file containing TIFF
tag and GeoKey values
imp_tif_dbg.txt
CNPYTIFF
TIFF
Canopy debug file containing TIFF tag
and GeoKey values
can_tif_dbg.txt
In addition to the files listed in Table 3-3, AERSURFACE will also automatically
generate an input summary file that replicates the control file inputs and a summary of warnings
and errors encountered during processing and a log file that records more detailed information
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about the input data that are read during program execution. These filenames can be defined by
the user at the time the program is executed at the command-line prompt. Refer to Section 1.0
details about how to run AERSURFACE from the command-line and how to specify the paths
and filenames for the input control file, log file, and summary file. Refer to Section 4.3 for
additional descriptive information about the various output files generated by AERSURFACE.
3.4 Sample AERSURFACE Control File
Figure 3-1 is a sample AERSURFACE control file for the location of the meteorological tower at
the Raleigh-Durham International Airport (RDU) using the 2016 NLCD. This example is for
demonstration purposes only, to demonstrate the usage of various keywords and is not intended
to be representative of how the site would normally be processed. A summary of the options used
in the sample control file follows.
In this example, the RDU station is processed as the PRIMARY meteorological station
which means site-specific data are not used. Otherwise, the NWS/FAA station would be
specified as the SECONDARY station. The default ZORAD option will be used to calculate the
surface roughness length. Because default options are used, the OPTIONS keyword and
parameters could be omitted in this case. For the ZORAD option, a default radius of 1 km will be
used to compute surface roughness length. Because this is the default radius value, the
ZORADIUS keyword and parameter could be omitted. Surface characteristics will be based on
2001 land cover which is supplemented with both impervious and canopy data. GRID and TIFF
debug files will be generated for each of the land cover, impervious, and canopy GeoTIFF data
files. Per the OU pathway, user-defined filenames will be used for the GRID debug files, but
default filenames will be used for the TIFF debug files.
The CLIMATE keyword indicates that moisture conditions are AVERAGE, but there is
at least one month with continuous snow cover (SNOW), and the regional climate conditions are
non-arid (NONARID). Months are reassigned from the default season assignments with March
reassigned from Spring to winter without continuous snow cover, and January is defined as
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having continuous snow cover meaning more than 50% of the month experienced continuous
snow cover. Note, because SNOW was specified on the CLIMATE keyword, AERSURFACE
will assume all winter months experience continuous snow cover unless winter months are
explicitly assigned to either winter with continuous snow (WINTERWS) or winter without
continuous snow (WINTERNS).
Based on the FREQSECT and SECTOR keywords, monthly values of surface
characteristics will be computed. Surface roughness length will be computed for three wind
sectors and only sector 2 which is largely comprised of runways will be processed using airport
surface characteristic values (lower surface roughness values). Figure 3-2 Shows the three
sectors defined in the sample control file in Figure 3-1, overlaid with land cover from the 2001
NLCD for RDU.
The RUNORNOT keyword indicates that AERSURFACE will attempt to run after
checking the control file.
3-23
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** Sample control file - for demonstration purposes only
CO STARTING
TITLEONE Sample AERSURFACE Control File
TITLETWO RDU - Met Tower, 2016 NLCD
** Using default options for OPTIONS keyword and parameters
OPTIONS PRIMARY ZORAD
DEBUGOPT GRID TIFF
CENTERLL 35.892300 -78.781900
NAD 8 3
DATAFILE NLCD2 016 "RDU_2016_NLCD_LC.tiff"
DATAFILE CNPY2 016 "RDU_2016_NLCD_Can.tiff"
DATAFILE MPRV2 016 "RDU_2016_NLCD_Imp.tiff"
** Use default 1 km radius
ZORADIUS 1.0
CLIMATE
AVERAGE SNOW
NONARID
** Get monthly values for three sectors
** Vary AP/Non-AP sectors
FREQ SECT MONTHLY 3 VARYAP
index start
end
SECTOR
1 30.00
60.00 NONAP
SECTOR
2 60.00
225.00 AP
SECTOR
3 225.00
3 0.00 NONAP
** Reassign
months with
continuous snow
SEASON
WINTERNS
12 2 3
SEASON
WINTERWS
1
SEASON
SPRING
4
5
SEASON
SUMMER
6
7 8
SEASON
AUTUMN
9
10 11
RUNORNOT
RUN
CO FINISHED
OU STARTING
SFCCHAR
NLCDGRID
CNPYGRID
MPRVGRID
OU FINISHED
"rdu 2016 lc can imp zorad sfc.txt"
"rdu 2016 lc can imp zorad lc grid.txt"
"rdu 2016 lc can imp zorad can grid.txt"
"rdu 2016 lc can imp zorad imp grid.txt"
Figure 3-1. Sample AERSURFACE Control File
3-24
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NLCD Land Cover Classification Legend
111 Open Water
12 Perennial Ice/ Snow
J 21 Developed, Open Space
22 Developed, Low Intensity
23 Developed, Medium Intensity
24 Developed, High Intensity
l_ J 31 Barren Land (Rock/Sand/Clay)
J 41 Deciduous Forest
142 Evergreen Forest
i 43 Mixed Forest
[ 151 Dwarf Scrub*
[ ]52 Shrub/Scrub
I 171 Grassland/Herbaceous
[ ] 72 Sedge/Herbaceous*
173 Lichens*
! 74 Moss*
I 181 Pasture/Hay
II 3 82 Cultivated Crops
90 Woody Wetlands
J 95 Emergent Herbaceous Wetlands
* Alaska only
KVWB
MSB
Figure 3-2. 2016 NLCD for RDU International with Wind Sectors
Starting at 30, 60, and 225 Degrees
3-25
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4.0 Running AERSURFACE
4.1 Command Prompt and Command-line Arguments
The AERSURFACE executable file1 available on EPA's SCRAM website has been
compiled for the Microsoft Windows operating system and runs at a command prompt.
AERSURFACE, can be run from the command prompt by entering the path and filename of the
AERSURFACE executable file (e.g., aersurface.exe) with up to three command-line arguments
which can be included to specify the path and filename of the input control file, the output
summary file, and the output log file, in that order. This is demonstrated as follows:
Path-to-aersurface.exe\aersurface
Path-to-aersurface.exe\aersurface path\controlJile
Path-to-aersurface.exe\aersurface path\controlJile path\summaryJile
Path-to-aersurface.exe\aersurface path\controlJile path\summaryJile path\logJile
The first example assumes that the control file is located in the working directory and is named
aer surf ace.inp. When executed in this way, the default names aersurf ace. out and aersurface.log
will be used for the names of the summary and log files, respectively. In the remaining examples,
the path and filename of the control file is specified. If the path and filename of the summary file
or subsequently the log file is not included, AERSURFACE will get the base path and filename
of the control file (without the extension) and set the path and filename of the summary and log
files equal to the base path and filename and add the extension .out and.log, respectively. The
1 Included with the AERSURFACE executable file are NAD Grid conversion files (conus.los and conus.las) for
converting coordinates between NAD27 and NAD83 datums for the conterminous U.S. (CONUS) and Alaska.
Earlier versions of AERSURFACE that processed only the 1992 NLCD allowed the user to specify coordinates
referenced to either the NAD27 datum or NAD83 and AERSURFACE would convert user coordinates or coordinates
derived from the NLCD file to be consistent. This capability has been carried forward for the CONUS and also works
for Alaska. When conversion is needed between NAD27 and NAD83, the NAD Grid conversions files provided with
the AERSURFACE executable (aersurface.exe) need to be stored in the directory with the executable. However,
AERSURFACE has not been extended to make similar conversions for older datums specific to Hawaii and Puerto
Rico. When running AERSURFACE for locations in Hawaii and Puerto Rico, the coordinates entered by the user
should be referenced to the NAD83 datum or the WGS84 ellipsoid, and NAD83 should be specified as the datum
entered in the AERSURFACE control file. AERSURFACE treats NAD83 and WGS84 identically.
4-1
-------
path to each of the files entered in the command prompt can be entered as an absolute or relative
path (i.e., relative to the working directory).
4.2 Error and Warning Messages
While processing the control file and input data files, AERSURFACE writes messages to
the summary file, log file, and to the screen. These could be in the form of errors and warnings
that were encountered when initially checking the format of the control file as well as
dependencies in the options selected or issues encountered while reading the data input files
during processing. Informational messages may also be recorded to document specific
information about the data that were processed. Errors, such as a malformed control file, invalid
options, or missing or incorrectly formatted data files will cause AERSURFACE to abort
processing prematurely. These errors will need to be corrected before AERSURFACE can
complete successfully. Warnings, however, do not halt processing, but should be evaluated by
the user after AERSURFACE has completed to ensure results were not affected. Some examples
of warnings include data values that are out-of-bounds or a default value is assumed. The user
should inspect both the summary and log output files and review all messages that were recorded
during processing and determine if the control file or data need to be evaluated to ensure the
results were not impacted in an adverse or unexpected manner.
4.3 Summary of Output Files Generated by AERSURFACE
This section provides a summary of the different files that can be generated by
AERSURFACE and their contents. The files that are described include the summary and log files
that are generated automatically during each AERSURFACE run, the required surface
characteristics file that contains the calculated values and is formatted for input to AERMET, and
the various optional debug files. For additional information on the output options used to
generate specific files, refer to Section 3.2.
4-2
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4.3.1 Auto-generated Files
Each time an AERSURFACE run is performed, a summary file and a log file are
automatically generated. The default filenames for these two files if not provided by the user are
aer surf ace.out and aer surface. log, respectively. These default filenames can be overridden with
user-defined names when AERSURFACE is executed from the command-prompt (see Section
4.1). Additional descriptions of these two files and their contents are provided in the next two
sections.
4.3.1.1 Summary File (aer surf ace, out)
The first part of the summary file replicates the AERSURFACE control file verbatim as a
record of the control file structure and exact options and inputs. The summary file also indicates
if the setup completed successfully, meaning there were no formatting issues or conflicts with the
options specified in the control file when it was checked before processing. If the setup
completes without error, then the summary file will subsequently indicate if processing the data
files completed successfully. All error, warning, and informational messages encountered are
listed at the bottom of the summary file.
4.3.1.2 Log File (aersurface.los)
The log file records detailed information about the datafiles as they are read such as the
filename and if the file was opened successfully, the spatial resolution of the file, the number of
rows and columns of data, and the organization of the data in the file. The log file also provides
the counts of each land category by sector within the area used to calculate the surface
characteristics values. Detailed warning and error messages are also recorded in the log file as
processing continues.
4-3
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4.3.2 Surface Characteristics
As stated in Section 3.3.1, the keyword SFCCHAR and the user-defined path and
filename of the surface characteristics file that contains calculated surface characteristic values
formatted for input to AERMET are the only required entries in the OU pathway. This file
includes a compact summary, in list format, of the processing options specified in the control
file. The lines that make up the summary of options contain the double asterisks (**) in the first
two columns of each line so that AERMET will ignore them. Following the options summary are
the frequency, number of sectors, and roughness flag, along with the sector definitions and
surface characteristic values formatted with the appropriate keywords as required by AERMET.
4.3.3 Debug Files
Whether or not debug files are created by AERSURFACE and which files are created is
controlled with the DEBUGOPT keyword on the CO pathway (see Section 3.2.3) in conjunction
with the type of datafiles processed in addition to land cover (i.e., impervious and canopy), and
the method used to calculate surface roughness length (i.e., ZORAD or ZOEFF, see Sections
2.4.1 and 3.2.2). Regardless which method is chosen or which debug options are selected,
AERSURFACE will only create those debug files that are consistent with the method specified
and the data that are input. AERSURFACE will not generate an error or abort processing if
debug options on the CO pathway or file types specified on the OU pathway are inconsistent
with the surface method specified or data that are input. For debug files created that are not
specified on the OU pathway, AERSURFACE will use the default filenames.
There are three categories of debug files: effective radius, TIFF debug, and grid files.
Each of these are ASCII text files that can be opened with a standard text editor. A summary of
the contents of each these are discussed in the sections that follow.
4-4
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4.3.3.1 Effective Radius File (default = effective radtxt)
The effective radius file is only applicable with the ZOEFF option for calculating
effective surface roughness. AERSURFACE generates this file when the ZOEFF secondary
keyword is specified with the OPTIONS keyword on the CO pathway and the EFFRAD
secondary keyword is specified with the DEBUGOPT keyword, also on the CO pathway. This
file provides a summary, by sector and month, of the calculated fetch, the effective roughness
computed traversing from the tower location, the effective roughness computed traversing
toward the tower, the final effective roughness value, and the mean roughness computed for each
concentric ring from the tower to just beyond 5 km. The default path and filename of this file can
be overridden using the EFFRAD primary keyword on the OU pathway. If omitted from the OU
pathway, the default filename, effective vad.txl, will be used, the file will be created in the
working directory.
4.3.3.2 TIFF Debug Files (defaults = lc_tif_dbg.txt, imp tif dbg.txt, and can tif dbg.txf)
AERSURFACE will create a separate TIFF debug file for each TIFF datafile processed
(i.e., land cover, impervious, and canopy) when the TIFF option is specified with the
DEBUGOPT keyword on the CO pathway (see Section 3.3.2). These debug files contain a record
of each of the TIFF tags and GeoKeys read during processing. The TIFF tags and GeoKeys store
information about the organization of the data within the file and how the data are georeferenced
for extraction and interpretation. This information can be used to troubleshoot the data files if
warnings are issued during processing or results are questionable. The default paths and
filenames of these files can be overridden using the primary keywords NLCDTIFF, MPRVTIFF,
and/or CNPYTIFF on the OU pathway. If omitted from the OU pathway, the default filenames,
lc_tif_dbg.txt, imp tif dbg.txt, and can tif dbg.txt, will be used, and the files will be created in
the working directory.
4-5
-------
4.3.3.3 Grid Files (defaults = landcover.txt, imyervious.txt, and canovv.txt)
Similar to the TIFF debug files, AERSURFACE will create separate grid debug files for
each TIFF datafile processed (e.g., land cover, impervious, and canopy) when the GRID option is
specified with the DEBUGOPT keyword on the CO pathway (see Section 3.3.2). Each of these
debug files contain a grid of the values extracted from the corresponding datafile with reference
information about the number of rows, columns, and the horizontal resolution of the data. The
default paths and filenames of these files can be overridden using the primary keywords
NLCDGRID, MPRVGRID, and/or CNPYGRID on the OU pathway. If omitted from the OU
pathway, the default filenames, landcover.txt, impervious.txt, and canopy.txt, will be used, and
the files will be created in the working directory.
4-6
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5.0 Appendix A: National Land Cover Database Definitions
Table 5-1. Original 1992 NLCD Class and Category Descriptions and Color Legend
Class\ Value
Classification Description
Water
areas of open water or permanent ice/snow cover.
11
Open Water - areas of open water, generally with less than 25% cover of vegetation/land cover.
12
Perennial Ice/Snow - areas characterized by year-long surface cover of ice and/or snow.
Developed
areas characterized by a high percentage (30 % or greater) of constructed materials (e.g. asphalt, concrete,
buildings, etc.).
21
Low Intensity Residential - areas with a mixture of constructed materials and vegetation. Constructed
materials account for 30% to 80% of the cover. Vegetation may account for 20% to 70 % of the cover. These
areas most commonly include single-family housing units. Population densities will be lower than in high
intensity residential areas.
22
High Intensity Residential - areas highly developed where people reside in high numbers. Examples include
apartment complexes and row houses. Vegetation accounts for less than 20% of the cover. Constructed
materials account for 80% tol00% of the cover.
23
Commercial/lndustrial/Transportation - areas of infrastructure (e.g. roads, railroads, etc.) and all highly
developed areas not classified as High Intensity Residential
Barren
areas characterized by bare rock, gravel, sand, silt, clay, or other earthen material, with little or no "green"
vegetation present regardless of its inherent ability to support life. Vegetation, if present, is more widely
spaced and scrubby than that in the green vegetated categories; lichen cover may be extensive.
31
Bare Rock/Sand/Clay - perennially barren areas of bedrock, desert pavement, scarps, talus, slides, volcanic
material, glacial debris, beaches, and other accumulations of earthen material.
32
Quarries/Strip Mines/Gravel Pits - areas of extractive mining activities with significant surface expression.
33
Transitional - areas of sparse vegetative cover (less than 25% of cover) that are dynamically changing from
one land cover to another, often because of land use activities. Examples include forest clear cuts, a
transition phase between forest and agricultural land, the temporary clearing of vegetation, and changes
due to natural causes (e.g. fire, flood, etc.).
Forest
areas characterized by tree cover (natural or semi-natural woody vegetation, generally greater than 6
meters tall); tree canopy accounts for 25% to 100% of the cover.
41
Deciduous Forest - areas dominated by trees where 75% or more of the tree species shed foliage
simultaneously in response to seasonal change.
42
Evergreen Forest - areas dominated by trees where 75% or more of the tree species maintain their leaves all
year. Canopy is never without green foliage.
43
Mixed Forest - areas dominated by trees where neither deciduous nor evergreen species represent more
than 75% of the cover present.
Shrubland
areas characterized by natural or semi-natural woody vegetation with aerial stems, generally less than 6
meters tall, with individuals or clumps not touching to interlocking. Both evergreen and deciduous species of
true shrubs, young trees, and trees or shrubs that are small or stunted because of environmental conditions
are included.
51
Shrubland - areas dominated by shrubs; shrub canopy accounts for 25 to 100% of the cover. Shrub cover is
generally greater than 25% when tree cover is less than 25%. Shrub cover may be less than 25% in cases
when the cover of other life forms (e.g. herbaceous or tree) is less than 25% and shrubs cover exceeds the
cover of the other life forms.
Non-natural
woody
areas dominated by non-natural woody vegetation; non-natural woody vegetative canopy accounts for 25%
to 100% of the cover. The non-natural woody classification is subject to the availability of sufficient ancillary
data to differentiate non-natural woody vegetation from natural woody vegetation.
5-1
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61
Orchards/Vineyards/Other - orchards, vineyards, and other areas planted or maintained for the production
of fruits, nuts, berries, or ornamentals.
Herbaceous
Upland
upland areas characterized by natural or semi-natural herbaceous vegetation; herbaceous vegetation
accounts for 75% to 100% of the cover.
71
Grasslands/Herbaceous - areas dominated by upland grasses and forbs. In rare cases, herbaceous cover is
less than 25%, but exceeds the combined cover of the woody species present. These areas are not subject to
intensive management, but they are often utilized for grazing.
Planted/Cultivated
areas characterized by herbaceous vegetation that has been planted or is intensively managed for the
production of food, feed, or fiber; or is maintained in developed settings for specific purposes. Herbaceous
vegetation accounts for 75% to 100% of the cover.
81
Pasture/Hay - areas of grasses, legumes, or grass-legume mixtures planted for livestock grazing or the
production of seed or hay crops.
82
Row Crops - areas used for the production of crops, such as corn, soybeans, vegetables, tobacco, and
cotton.
83
Small Grains - areas used for the production of graminoid crops such as wheat, barley, oats, and rice.
84
Fallow - areas used for the production of crops that do not exhibit visible vegetation as a result of being
tilled in a management practice that incorporates prescribed alternation between cropping and tillage.
85
Urban/Recreational Grasses - vegetation (primarily grasses) planted in developed settings for recreation,
erosion control, or aesthetic purposes. Examples include parks, lawns, golf courses, airport grasses, and
industrial site grasses.
Wetlands
areas where the soil or substrate is periodically saturated with or covered with water as defined by Cowardin
et a!., (1979).
91
Woody Wetlands - areas where forest or shrubland vegetation accounts for 25% to 100 % of the cover and
the soil or substrate is periodically saturated with or covered with water.
92
Emergent Herbaceous Wetlands - areas where perennial herbaceous vegetation accounts for 75% to 100%
of the cover and the soil or substrate is periodically saturated with or covered with water.
Reproduced from the Multi-Resolution Land Characteristics Consortium Website at http://www.mrlc.gov
5-2
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Table 5-2. Annual NLCD Class and Category Descriptions and Color Legend
Class\ Value
Classification Description
Water
11
Open Water - areas of open water, generally with less than 25% cover of vegetation or soil.
12
Perennial Ice/Snow - areas characterized by a perennial cover of ice and/or snow, generally greater than
25% of total cover.
Developed
21
Developed, Open Space - areas with a mixture of some constructed materials, but mostly vegetation in the
form of lawn grasses. Impervious surfaces account for less than 20% of total cover. These areas most
commonly include large-lot single-family housing units, parks, golf courses, and vegetation planted in
developed settings for recreation, erosion control, or aesthetic purposes.
22
Developed, Low Intensity - areas with a mixture of constructed materials and vegetation. Impervious
surfaces account for 20% to 49% percent of total cover. These areas most commonly include single-family
housing units.
23
Developed, Medium Intensity - areas with a mixture of constructed materials and vegetation. Impervious
surfaces account for 50% to 79% of the total cover. These areas most commonly include single-family
housing units.
24
Developed High Intensity -highly developed areas where people reside or work in high numbers. Examples
include apartment complexes, row houses and commercial/industrial. Impervious surfaces account for 80%
to 100% of the total cover.
Barren
31
Barren Land (Rock/Sand/Clay) - areas of bedrock, desert pavement, scarps, talus, slides, volcanic material,
glacial debris, sand dunes, strip mines, gravel pits and other accumulations of earthen material. Generally,
vegetation accounts for less than 15% of total cover.
Forest
41
Deciduous Forest - areas dominated by trees generally greater than 5 meters tall, and greater than 20% of
total vegetation cover. More than 75% of the tree species shed foliage simultaneously in response to
seasonal change.
42
Evergreen Forest - areas dominated by trees generally greater than 5 meters tall, and greater than 20% of
total vegetation cover. More than 75% of the tree species maintain their leaves all year. Canopy is never
without green foliage.
43
Mixed Forest - areas dominated by trees generally greater than 5 meters tall, and greater than 20% of total
vegetation cover. Neither deciduous nor evergreen species are greater than 75% of total tree cover.
Shrubland
51
Dwarf Scrub - Alaska only areas dominated by shrubs less than 20 centimeters tall with shrub canopy
typically greater than 20% of total vegetation. This type is often co-associated with grasses, sedges, herbs,
and non-vascular vegetation.
52
Shrub/Scrub - areas dominated by shrubs; less than 5 meters tall with shrub canopy typically greater than
20% of total vegetation. This class includes true shrubs, young trees in an early successional stage or trees
stunted from environmental conditions.
Herbaceous
71
Grassland/Herbaceous - areas dominated by gramanoid or herbaceous vegetation, generally greater than
80% of total vegetation. These areas are not subject to intensive management such as tilling, but can be
utilized for grazing.
72
Sedge/Herbaceous - Alaska only areas dominated by sedges and forbs, generally greater than 80% of total
vegetation. This type can occur with significant other grasses or other grass like plants, and includes sedge
tundra, and sedge tussock tundra.
73
Lichens - Alaska only areas dominated by fruticose or foliose lichens generally greater than 80% of total
vegetation.
5-3
-------
74
Moss - Alaska only areas dominated by mosses, generally greater than 80% of total vegetation.
Planted/Cultivated
81
Pasture/Hay - areas of grasses, legumes, or grass-legume mixtures planted for livestock grazing or the
production of seed or hay crops, typically on a perennial cycle. Pasture/hay vegetation accounts for greater
than 20% of total vegetation.
82
Cultivated Crops - areas used for the production of annual crops, such as corn, soybeans, vegetables,
tobacco, and cotton, and also perennial woody crops such as orchards and vineyards. Crop vegetation
accounts for greater than 20% of total vegetation. This class also includes all land being actively tilled.
Wetlands
90
Woody Wetlands - areas where forest or shrubland vegetation accounts for greater than 20% of vegetative
cover and the soil or substrate is periodically saturated with or covered with water.
95
Emergent Herbaceous Wetlands - Areas where perennial herbaceous vegetation accounts for greater than
80% of vegetative cover and the soil or substrate is periodically saturated with or covered with water.
Reproduced from the Multi-Resolution Land Characteristics Consortium Website at http://www.mrlc.gov
5-4
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6,0 Appendix B. Surface Characteristic Lookup Tables
Table 6-1 through Table 6-6 provide the values of albedo, Bowen ratio, and surface roughness,
respectively, based on the original 1992 NLCD land cover categories. Each table includes a column
containing references used in estimating the values for each surface characteristic parameter and each land
cover category. As explained in Section 2.0, more than one value of surface characteristics may be listed
for certain land cover categories depending on user responses to specific prompts regarding the site
location.
6-1
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Table 6-1. Seasonal Values of Albedo for the original 1992 NLCD
Class
Number
Class Name
Seasonal Albedo Values1
Reference
1
2
3
4
5
11
Open Water
0.1
0.1
0.1
0.1
0.1
AERMET2'3
12
Perennial Ice/Snow
0.7
0.7
0.6
0.6
0.6
Stull & Garratt4
21
Low Intensity Residential
0.18
0.45
0.16
0.16
0.16
Estimate5
22
High Intensity Residential
0.18
0.35
0.18
0.18
0.18
Stull6 & AERMET7
23
Commercial/lndustrial/Transp
0.18
0.35
0.18
0.18
0.18
Stull6 & AERMET7
31
Bare Rock/Sand/Clay (Arid Region)
0.2
NA
0.2
0.2
0.2
Garratt8
Bare Rock/Sand/Clay (Non-arid Region)
0.2
0.6
0.2
0.2
0.2
Garratt8 & AERMET7
32
Quarries/Strip Mines/Gravel
0.2
0.6
0.2
0.2
0.2
Garratt8 & AERMET7
33
Transitional
0.18
0.45
0.18
0.18
0.18
Estimate9
41
Deciduous Forest
0.17
0.5
0.16
0.16
0.16
Stull6 & AERMET7
42
Evergreen Forest
0.12
0.35
0.12
0.12
0.12
Stull6 & AERMET7
43
Mixed Forest
0.14
0.42
0.14
0.14
0.14
Estimate10
51
Shrubland (Arid Region)
0.25
NA
0.25
0.25
0.25
Stull6
Shrubland (Non-arid Region)
0.18
0.5
0.18
0.18
0.18
Estimaten&AERMET7
61
Orchards/Vineyards/Other
0.18
0.5
0.14
0.18
0.18
Estimate12
71
Grasslands/Herbaceous
0.2
0.6
0.18
0.18
0.18
AERMET2
81
Pasture/Hay
0.18
0.6
0.14
0.2
0.2
AERMET2,13
82
Row Crops
0.18
0.6
0.14
0.2
0.2
AERMET2,13
83
Small Grains
0.18
0.6
0.14
0.2
0.2
AERMET2,13
84
Fallow
0.18
0.6
0.18
0.18
0.18
Garratt8
85
Urban/Recreational Grasses
0.18
0.6
0.15
0.15
0.15
Estimate14
91
Woody Wetlands
0.14
0.3
0.14
0.14
0.14
Stull6 & AERMET7
92
Emergent Herbaceous Wetlands
0.14
0.3
0.14
0.14
0.14
Stull6 & AERMET7
6-2
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1 Values are listed for the following seasonal categories: 1 - Late autumn after frost and harvest; or winter with
no snow; 2 - Winter with continuous snow on ground; 3 - Transitional spring with partial green coverage or
short annuals; 4 - Midsummer with lush vegetation; 5 - Autumn with unharvested cropland
2 Estimate based on AERMET User's Guide, Table 4-1.
3 We assume no freeze of the water and no seasonal changes in albedo.
4 Estimate based on Stull, Table C-7 and Garratt, Table A8. Assume fresher snow and more ice in seasonal categories 3 & 4
and older snow in seasonal categories 1, 2, & 5.
5 Assume an equal mix of three classes: "High Intensity Residential", "Mixed Forest", and "Urban/Recreational Grasses."
6 Estimate based on Stull, Table C-7.
7 Estimate based on AERMET User's Guide, Table 4-1 albedo value for winter with continuous snow cover.
8 Estimate based on Garratt, Table A8.
9 Assume "Transitional" is similar to Class 84: "Fallow". A warning will be issues to the user if this category appears in more
than 10% of the land cover data.
10 Estimate based on the average of Classes 41 and 42.
11 Estimate based on the non-arid shrubland having more vegetation that the arid-region shrubland.
12 Estimate based Class 51: "Shrubland (non-arid region)" for seasonal categories 1, 2 & 4 and AERMET User's Guide
("Cultivated Land") for seasonal categories 3 & 5.
13 Estimate based on AERMET User's Guide; assume more vegetation in summer and soil being wetter in spring than in fall.
14 Estimate based on AERMET User's Guide ("Cultivated Land") for seasonal category 3 & 4, and Garratt, Table A8 for
seasonal categories 1, 2 & 5.
6-3
-------
Table 6-2. Seasonal Values of Bowen Ratio for the original 1992 NLCD
Class
Number
Class Name
Seasonal Bowen Ratio1
Average
Seasonal Bowen Ratio1
Wet
Seasonal Bowen Ratio1
Dry
Reference
1
22
3
4
5
1
22
3
4
5
1
22
3
4
5
11
Open Water
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
AERMET&Oke3
12
Perennial Ice/Snow
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
AERMET&Oke3
21
Low Intensity Residential
1.0
0.5
0.8
0.8
1.0
0.6
0.5
0.6
0.6
0.6
2.5
0.5
2.0
2.0
2.5
Estimate4
22
High Intensity Residential
1.5
0.5
1.5
1.5
1.5
1.0
0.5
1.0
1.0
1.0
3.0
0.5
3.0
3.0
3.0
AERMET&Oke3
23
Commercial/lndustrial/Transp
1.5
0.5
1.5
1.5
1.5
1.0
0.5
1.0
1.0
1.0
3.0
0.5
3.0
3.0
3.0
AERMET&Oke3
31
Bare Rock/Sand/Clay
(Arid Region)
6.0
NA
3.0
4.0
6.0
2.0
NA
1.0
1.5
2
10.0
NA
5.0
6.0
10
AERMET&Oke3
Bare Rock/Sand/Clay
(Non-arid Region)
1.5
0.5
1.5
1.5
1.5
1.0
0.5
1.0
1.0
1.0
3.0
0.5
3.0
3.0
3.0
AERMET&Oke3
32
Quarries/Strip Mines/Gravel
1.5
0.5
1.5
1.5
1.5
1.0
0.5
1.0
1.0
1.0
3.0
0.5
3.0
3.0
3.0
AERMET&Oke3
33
Transitional
1.0
0.5
1.0
1.0
1.0
0.7
0.5
0.7
0.7
0.7
2.0
0.5
2.0
2.0
2.0
Estimate5
41
Deciduous Forest
1.0
0.5
0.7
0.3
1.0
0.4
0.5
0.3
0.2
0.4
2.0
0.5
1.5
0.6
2.0
AERMET&Oke3
42
Evergreen Forest
0.8
0.5
0.7
0.3
0.8
0.3
0.5
0.3
0.2
0.3
1.5
0.5
1.5
0.6
1.5
AERMET&Oke3
43
Mixed Forest
0.9
0.5
0.7
0.3
0.9
0.35
0.5
0.3
0.2
0.35
1.75
0.5
1.5
0.6
1.75
Estimate6
51
Shrubland (Arid Region)
6.0
NA
3.0
4.0
6.0
2.0
NA
1.0
1.5
2.0
10.0
NA
5.0
6.0
10.0
AERMET&Oke3
Shrubland (Non-arid Region)
1.5
0.5
1.0
1.0
1.5
1.0
0.5
0.8
0.8
1.0
3.0
0.5
2.5
2.5
3.0
Estimate7
61
Orchards/Vineyards/Other
0.7
0.5
0.3
0.5
0.7
0.4
0.5
0.2
0.3
0.4
2.0
0.5
1.0
1.5
2.0
AERMET&Oke3
6-4
-------
71
Grasslands/Herbaceous
1.0
0.5
0.4
0.8
1.0
0.5
0.5
0.3
0.4
0.5
2.0
0.5
1.0
2.0
2.0
AERMET&Oke3
81
Pasture/Hay
0.7
0.5
0.3
0.5
0.7
0.4
0.5
0.2
0.3
0.4
2.0
0.5
1.0
1.5
2.0
AERMET&Oke3
82
Row Crops
0.7
0.5
0.3
0.5
0.7
0.4
0.5
0.2
0.3
0.4
2.0
0.5
1.0
1.5
2.0
AERMET&Oke3
83
Small Grains
0.7
0.5
0.3
0.5
0.7
0.4
0.5
0.2
0.3
0.4
2.0
0.5
1.0
1.5
2.0
AERMET&Oke3
84
Fallow
0.7
0.5
0.3
0.5
0.7
0.4
0.5
0.2
0.3
0.4
2.0
0.5
1.0
1.5
2.0
AERMET&Oke3
85
Urban/Recreational Grasses
0.7
0.5
0.3
0.5
0.7
0.4
0.5
0.2
0.3
0.4
2.0
0.5
1.0
1.5
2.0
AERMET&Oke3
91
Woody Wetlands
0.3
0.5
0.2
0.2
0.2
0.1
0.5
0.1
0.1
0.1
0.2
0.5
0.2
0.2
0.2
Estimate7
92
Emergent Herbaceous
Wetlands
0.1
0.5
0.1
0.1
0.1
0.1
0.5
0.1
0.1
0.1
0.2
0.5
0.2
0.2
0.2
AERMET&Oke3
1 Values are listed for the following seasonal categories: 1 - Late autumn after frost and harvest; or winter with no snow; 2 - Winter with
continuous snow on ground; 3 - Transitional spring with partial green coverage or short annuals; 4 - Midsummer with lush vegetation; 5 -
Autumn with unharvested cropland
2 Values for seasonal category 2 are based on the AERMET User's Guide (EPA, 2018a) and Oke (1978), Tables 4-2a-c, Bowen ratio values for winter with
continuous snow cover, except for class 11 with the assumption the water does not freeze.
3 Values for seasonal categories 1, 2, 3 & 5 are based on AERMET User's Guide (EPA, 2018a), Tables 4-2a-c and Oke (1978).
4 Estimate based on composition being an equal mix of three classes: "High Intensity Residential", "Mixed Forest", and "Urban/Recreational Grasses.
5 Estimate based on the Bowen ratio of "Transitional" being between the Bowen ratio of Classes 31 and 71.
6 Assume "Mixed Forest" is composed of equal parts of "Deciduous Forest" and "Evergreen Forest."
7 Estimate based on comparison to Bowen ratio for other classes.
6-5
-------
Table 6-3. Seasonal Values of Surface Roughness (m) for the original 1992 NLCD
Class
Number
Class Name
Seasonal Surface Roughness1 (m)
Reference
1
2
3
4
5
11
Open Water
0.001
0.001
0.001
0.001
0.001
Stull2
12
Perennial Ice/Snow
0.002
0.002
0.002
0.002
0.002
Stull2
21
Low Intensity Residential
0.30
0.30
0.40
0.40
0.40
Estimate3
22
High Intensity Residential
1.0
1.0
1.0
1.0
1.0
AERMET4
23
Commercial/lndust/Transp
(Airport)
0.07
0.07
0.07
0.07
0.07
Estimate5
Commercial/lndustrial/Transp
(Non-airport)
0.7
0.7
0.7
0.7
0.7
Estimate5
31
Bare Rock/Sand/Clay
(Arid Region)
0.05
NA
0.05
0.05
0.05
Slade6
Bare Rock/Sand/Clay
(Non-arid Region)
0.05
0.05
0.05
0.05
0.05
Slade6
32
Quarries/Strip Mines/Gravel
0.3
0.3
0.3
0.3
0.3
Estimate7
33
Transitional
0.2
0.2
0.2
0.2
0.2
Estimate8
41
Deciduous Forest
0.6
0.5
1.0
1.3
1.3
AERMET4
42
Evergreen Forest
1.3
1.3
1.3
1.3
1.3
AERMET4
43
Mixed Forest
0.9
0.8
1.1
1.3
1.3
Estimate9
51
Shrubland
(Arid Region)
0.15
NA
0.15
0.15
0.15
50% Cat. 51 (Non-Arid)10
Shrubland
(Non-arid Region)
0.3
0.15
0.3
0.3
0.3
AERMET4
61
Orchards/Vineyards/Other
0.1
0.05
0.2
0.3
0.3
Garratt11
71
Grasslands/Herbaceous
0.01
0.005
0.05
0.1
0.1
AERMET4
81
Pasture/Hay
0.02
0.01
0.03
0.15
0.15
Garratt11 & Slade12
82
Row Crops
0.02
0.01
0.03
0.2
0.2
Garratt11 & Slade12
83
Small Grains
0.02
0.01
0.03
0.15
0.15
Garratt11 & Slade12
84
Fallow
0.02
0.01
0.02
0.05
0.05
Estimate13
85
Urban/Recreational Grasses
0.01
0.005
0.015
0.02
0.015
Randerson14
91
Woody Wetlands
0.4
0.3
0.5
0.5
0.5
Estimate15
92
Emergent Herbaceous
Wetlands
0.2
0.1
0.2
0.2
0.2
AERMET4
6-6
-------
1 Values are listed for the following seasonal categories: 1 - Late autumn after frost and harvest; or winter with
no snow; 2 - Winter with continuous snow on ground; 3 - Transitional spring with partial green coverage or short
annuals; 4 - Midsummer with lush vegetation; 5 - Autumn with unharvested cropland
2 Estimate based on Stull, Fig 9.6. We have specified a larger roughness than the AERMET "calm open sea"
roughness value because we have assumed that most of the water is closer to land and will experience waves
and be closer to the shoreline, increasing roughness.
3 Assume 50% "High Intensity Residential" (22), 25% "Mixed Forest" (43), and 25% "Urban/Recreational Grasses"
(85), using a weighted geometric mean value.
4 Based on the AERMET User's Guide (EPA, 2018a).
5 For airport sites, assume 90% of land cover is 'Transportation" with roughness similar to Class 31 (Bare Rock/
Sand/ Clay) and 10% is "Commercial/Industrial" with roughness similar to Class 22 (High Intensity Residential).
For non-airport, assume 10% of land cover is "Transportation" and 90% is "Commercial/Industrial". Weighted
geometric mean values are used.
6 Estimate based on Slade, Table 3-1, assuming the surface is not completely level due to inclusion of some
larger rocks.
7 Estimate reflecting "significant surface expression"
8 Estimate reflecting significant mix of different land cover classes. A warning will be issued to the user if this
category appears in more than 10% of the land cover data.
9 Assume "Mixed Forest" is 50% "Deciduous Forest" and 50% "Evergreen Forest", using a weighted geometric
mean value.
10 Assume arid region would have approximately 50% less vegetation than a non-arid region.
11 Estimate based on Garratt, Table A6.
12 Estimate based on Slade, Table 3-1
13 Based on class 31 ("Bare Rock/Sand/Clay") for seasonal categories 1 &2 and 81, 82, 83 ("Pasture/Hay", "Row
Crops" & "Small Grains") for seasonal categories 3, 4, & 5, with seasonal category 5 having a more similar
amount of vegetation to seasonal category 3 and, therefore, the same roughness.
14 Estimate based on Randerson, Table 5.4
15 Assume 50% Mixed Forest (43) and 50% Emergent Herb Wetlands (92), using a weighted geometric mean
value.
6-7
-------
Table 6-4. Seasonal Values of Albedo for the Annual NLCD
Class
Number
Class Name
Seasonal Albedo Values1
Reference
1
2
3
4
5
11
Open Water
0.1
0.1
0.1
0.1
0.1
NLCD 1992 Cat. 11
12
Perennial Ice/Snow
0.7
0.7
0.6
0.6
0.6
NLCD 1992 Cat. 12
21
Developed, Open Space
0.18
0.6
0.15
0.15
0.15
NLCD 1992 Cat. 85
22
Developed, Low Intensity
0.18
0.45
0.16
0.16
0.16
NLCD 1992 Cat. 21
23
Developed, Medium Intensity
0.18
0.18
0.18
0.18
0.18
NLCD 1992 Cat. 23
24
Developed, High Intensity
0.18
0.25
0.18
0.18
0.18
NLCD 1992 Cat. 23
31
Barren Land (Rock/Sand/Clay) (Arid Region)
0.2
NA
0.2
0.2
0.2
NLCD 1992 Cat. 31
Barren Land (Rock/Sand/Clay) (Non-arid Region)
0.2
0.6
0.2
0.2
0.2
NLCD 1992 Cat. 31
32
Unconsolidated Shore
0.14
0.3
0.14
0.14
0.14
NLCD 1992 Cat. 91
41
Deciduous Forest
0.17
0.5
0.16
0.16
0.16
NLCD 1992 Cat. 41
42
Evergreen Forest
0.12
0.35
0.12
0.12
0.12
NLCD 1992 Cat. 42
43
Mixed Forest
0.14
0.42
0.14
0.14
0.14
NLCD 1992 Cat. 43
51
Dwarf Scrub (Arid Region)
0.25
NA
0.25
0.25
0.25
NLCD 1992 Cat. 51
Dwarf Scrub (Non-arid Region)
0.18
0.5
0.18
0.18
0.18
NLCD 1992 Cat. 51
52
Shrub/Scrub (Arid Region)
0.25
NA
0.25
0.25
0.25
NLCD 1992 Cat. 51
Shrub/Scrub (Non-arid Region)
0.18
0.5
0.18
0.18
0.18
NLCD 1992 Cat. 51
71
Grasslands/Herbaceous
0.2
0.6
0.18
0.18
0.18
NLCD 1992 Cat. 71
72
Sedge/Herbaceous
0.2
0.6
0.18
0.18
0.18
NLCD 1992 Cat. 71
73
Lichens
0.2
0.6
0.18
0.18
0.18
NLCD 1992 Cat. 71
74
Moss
0.2
0.6
0.18
0.18
0.18
NLCD 1992 Cat. 71
81
Pasture/Hay
0.18
0.6
0.14
0.2
0.2
NLCD 1992 Cat. 81
82
Cultivated Crops
0.18
0.6
0.14
0.2
0.2
NLCD 1992 Cat. 82
90
Woody Wetlands
0.14
0.3
0.14
0.14
0.14
NLCD 1992 Cat. 91
91
Palustrine Forested Wetland
0.14
0.3
0.14
0.14
0.14
NLCD 1992 Cat. 91
92
Palustrine Scrub/Shrub Wetland
0.14
0.3
0.14
0.14
0.14
NLCD 1992 Cat. 91
93
Estuarine Forested Wetland
0.14
0.3
0.14
0.14
0.14
NLCD 1992 Cat. 91
94
Estuarine Scrub/Shrub Wetland
0.14
0.3
0.14
0.14
0.14
NLCD 1992 Cat. 91
95
Emergent Herbaceous Wetland
0.14
0.3
0.14
0.14
0.14
NLCD 1992 Cat. 92
96
Palustrine Emergent Wetland (Persistent)
0.14
0.3
0.14
0.14
0.14
NLCD 1992 Cat. 92
97
Estuarine Emergent Wetland
0.14
0.3
0.14
0.14
0.14
NLCD 1992 Cat. 92
98
Palustrine Aquatic Bed
0.14
0.3
0.14
0.14
0.14
NLCD 1992 Cat. 92
99
Estuarine Aquatic Bed
0.14
0.3
0.14
0.14
0.14
NLCD 1992 Cat. 92
1 Values are listed for the following seasonal categories: 1 - Late autumn after frost and harvest; or winter with
no snow; 2 - Winter with continuous snow on ground; 3 - Transitional spring with partial green coverage or
short annuals; 4 - Midsummer with lush vegetation; 5 - Autumn with unharvested cropland
6-8
-------
Table 6-5. Seasonal Values of Bowen Ratio for the Annual NLCD
Class
Number
Class Name
Seasonal Bowen Ratio1
Average
Seasonal Bowen Ratio1
Wet
Seasonal Bowen Ratio1
Dry
Reference
1
2
3
4
5
1
2
3
4
5
1
2
3
4
5
11
Open Water
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
NLCD 1992 Cat. 11
12
Perennial Ice/Snow
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
NLCD 1992 Cat. 12
21
Developed, Open Space
0.7
0.5
0.3
0.5
0.7
0.4
0.5
0.2
0.3
0.4
2.0
0.5
1.0
1.5
2.0
NLCD 1992 Cat. 85
22
Developed, Low Intensity
1.0
0.5
0.8
0.8
1.0
0.6
0.5
0.6
0.6
0.6
2.5
0.5
2.0
2.0
2.5
NLCD 1992 Cat. 21
23
Developed, Medium Intensity
1.2
0.5
1.1
1.1
1.2
0.8
0.5
0.8
0.8
0.8
3.0
0.5
3.0
3.0
3.0
Estimated2
24
Developed, High Intensity
1.5
0.5
1.5
1.5
1.5
1.0
0.5
1.0
1.0
1.0
3.0
0.5
3.0
3.0
3.0
NLCD 1992 Cat. 23
31
Barren Land (Rock/Sand/Clay)
(Arid Region)
6.0
NA
3.0
4.0
6.0
2.0
NA
1.0
1.5
2.0
10.0
NA
5.0
6.0
10.0
NLCD 1992 Cat. 31
Barren Land (Rock/Sand/Clay)
(Non-arid Region)
1.5
0.5
1.5
1.5
1.5
1.0
0.5
1.0
1.0
1.0
3.0
0.5
3.0
3.0
3.0
NLCD 1992 Cat. 31
32
Unconsolidated Shore
0.2
0.5
0.2
0.2
0.2
0.1
0.5
0.1
0.1
0.1
0.2
0.5
0.2
0.2
0.2
NLCD 1992 Cat. 91
41
Deciduous Forest
1.0
0.5
0.7
0.3
1.0
0.4
0.5
0.3
0.2
0.4
2.0
0.5
1.5
0.6
2.0
NLCD 1992 Cat. 41
42
Evergreen Forest
0.8
0.7
0.3
0.3
0.8
0.3
0.5
0.3
0.2
0.3
1.5
0.5
1.5
0.6
1.5
NLCD 1992 Cat. 42
43
Mixed Forest
0.9
0.5
0.7
0.3
0.9
0.35
0.5
0.3
0.2
0.35
1.75
0.5
1.5
0.6
1.75
NLCD 1992 Cat. 43
51
Dwarf Scrub
(Arid Region)
4.0
NA
2.0
3.0
4.0
1.5
NA
0.8
0.9
1.5
7.0
NA
4.0
6.0
7.0
Estimated from Cat 52
Dwarf Scrub
(Non-arid Region)
1.5
0.5
1.0
1.0
1.5
1.0
0.5
0.8
0.8
1.0
3.0
0.5
2.5
2.5
3.0
NLCD 1992 Cat. 51
52
Shrub/Scrub
(Arid Region)
6.0
NA
3.0
4.0
6.0
2.0
NA
1.0
1.5
2.0
10.0
NA
5.0
6.0
10.0
NLCD 1992 Cat. 51
Shrub/Scrub
(Non-arid Region)
1.5
0.5
1.0
1.0
1.5
1.0
0.5
0.8
0.8
1.0
3.0
0.5
2.5
2.5
3.0
NLCD 1992 Cat. 51
71
Grasslands/Herbaceous
1.0
0.5
0.4
0.8
1.0
0.5
0.5
0.3
0.4
0.5
2.0
0.5
1.0
2.0
2.0
NLCD 1992 Cat. 71
6-9
-------
72
73
74
81
82
90
91
92
93
94
95
96
97
98
99
1
2
Sedge/Herbaceous
1.0
0.5
0.4
0.8
1.0
0.5
0.5
0.3
0.4
0.5
2.0
0.5
1.0
2.0
2.0
NLCD 1992 Cat. 71
Lichens
1.0
0.5
0.4
0.8
1.0
0.5
0.5
0.3
0.4
0.5
2.0
0.5
1.0
2.0
2.0
NLCD 1992 Cat. 71
Moss
1.0
0.5
0.4
0.8
1.0
0.5
0.5
0.3
0.4
0.5
2.0
0.5
1.0
2.0
2.0
NLCD 1992 Cat. 71
Pasture/Hay
0.7
0.5
0.3
0.5
0.7
0.4
0.5
0.2
0.3
0.4
2.0
0.5
1.0
1.5
2.0
NLCD 1992 Cat. 81
Cultivated Crops
0.7
0.5
0.3
0.5
0.7
0.4
0.5
0.2
0.3
0.4
2.0
0.5
1.0
1.5
2.0
NLCD 1992 Cat. 82
Woody Wetlands
0.2
0.5
0.2
0.2
0.2
0.1
0.5
0.1
0.1
0.1
0.2
0.5
0.2
0.2
0.2
NLCD 1992 Cat. 91
Palustrine Forested Wetland
0.2
0.5
0.2
0.2
0.2
0.1
0.5
0.1
0.1
0.1
0.2
0.5
0.2
0.2
0.2
NLCD 1992 Cat. 91
Palustrine Scrub/Shrub
0.2
0.5
0.2
0.2
0.2
0.1
0.5
0.1
0.1
0.1
0.2
0.5
0.2
0.2
0.2
NLCD 1992 Cat. 91
Estuarine Forested Wetland
0.2
0.5
0.2
0.2
0.2
0.1
0.5
0.1
0.1
0.1
0.2
0.5
0.2
0.2
0.2
NLCD 1992 Cat. 91
Estuarine Scrub/Shrub
0.2
0.5
0.2
0.2
0.2
0.1
0.5
0.1
0.1
0.1
0.2
0.5
0.2
0.2
0.2
NLCD 1992 Cat. 91
Emergent Herbaceous
0.1
0.5
0.1
0.1
0.1
0.1
0.5
0.1
0.1
0.1
0.2
0.5
0.2
0.2
0.2
NLCD 1992 Cat. 92
Palustrine Emergent Wetland
0.1
0.5
0.1
0.1
0.1
0.1
0.5
0.1
0.1
0.1
0.2
0.5
0.2
0.2
0.2
NLCD 1992 Cat. 92
Estuarine Emergent Wetland
0.1
0.5
0.1
0.1
0.1
0.1
0.5
0.1
0.1
0.1
0.2
0.5
0.2
0.2
0.2
NLCD 1992 Cat. 92
Palustrine Aquatic Bed
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
NLCD 1992 Cat. 11
Estuarine Aquatic Bed
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
NLCD 1992 Cat. 11
Values are listed for the following seasonal categories: 1 - Late autumn after frost and harvest; or winter with no snow; 2 - Winter with continuous
snow on ground; 3 - Transitional spring with partial green coverage or short annuals; 4 - Midsummer with lush vegetation; 5 - Autumn with
unharvested cropland
Estimated from categories 22 (Developed - Low Intensity) and 24 (Developed - High Intensity).
6-10
-------
Table 6-6. Seasonal Values of Surface Roughness for the Annual NLCD
Class
Number
Class Name
Seasonal Surface Roughness1 (m)
Reference
1
2
3
4
5
11
Open Water
0.001
0.001
0.001
0.001
0.001
NLCD 1992 Cat. 11
12
Perennial Ice/Snow
0.002
0.002
0.002
0.002
0.002
NLCD 1992 Cat. 12
21
Developed, Open Space (Airport)
0.02
0.01
0.02
0.03
0.03
Estimated2
Developed, Open Space (Non-airport)
0.02
0.01
0.03
0.04
0.03
Estimated2
22
Developed, Low Intensity (Airport)
0.03
0.02
0.03
0.04
0.03
Estimated2
Developed, Low Intensity (Non-airport)
0.07
0.05
0.09
0.1
0.09
Estimated2
23
Developed, Medium Intensity (Airport)
0.05
0.04
0.06
0.06
0.06
Estimated2
Developed, Medium Intensity (Non-airport)
0.3
0.2
0.3
0.3
0.3
Estimated2
24
Developed, High Intensity (Airport)
0.07
0.07
0.07
0.08
0.08
Estimated2
Developed, High Intensity (Non-airport)
0.7
0.7
0.7
0.7
0.7
Estimated2
31
Barren Land (Rock/Sand/Clay) (Arid Region)
0.05
NA
0.05
0.05
0.05
NLCD 1992 Cat. 31
Barren Land (Rock/Sand/Clay) (Non-arid
Region)
0.05
0.01
0.05
0.05
0.05
NLCD 1992 Cat. 31
32
Unconsolidated Shore
0.05
0.01
0.05
0.05
0.05
NLCD 1992 Cat. 31
41
Deciduous Forest
0.6
0.5
1.0
1.3
1.3
NLCD 1992 Cat. 41
42
Evergreen Forest
1.3
1.3
1.3
1.3
1.3
NLCD 1992 Cat. 42
43
Mixed Forest
0.9
0.8
1.1
1.3
1.3
NLCD 1992 Cat. 43
51
Dwarf Scrub (Arid Region)
0.05
NA
0.05
0.05
0.05
NLCD 1992 Cat. 51
Dwarf Scrub (Non-arid Region)
0.1
0.05
0.1
0.1
0.1
NLCD 1992 Cat. 51
52
Shrub/Scrub (Arid Region)
0.15
NA
0.15
0.15
0.15
NLCD 1992 Cat. 51
Shrub/Scrub (Non-arid Region)
0.3
0.15
0.3
0.3
0.3
NLCD 1992 Cat. 51
71
Grasslands/Herbaceous
0.01
0.005
0.05
0.1
0.1
NLCD 1992 Cat. 71
72
Sedge/Herbaceous
0.01
0.005
0.05
0.1
0.1
NLCD 1992 Cat. 71
73
Lichens
0.01
0.005
0.05
0.05
0.05
Estimated
6-11
-------
74
Moss
0.01
0.005
0.05
0.05
0.05
Estimated
81
Pasture/Hay (Airport)
0.02
0.01
0.02
0.03
0.03
NLCD 1992 Cat. 21
Pasture/Hay (Non-airport)
0.02
0.01
0.03
0.15
0.15
NLCD 1992 Cat. 81
82
Cultivated Crops (Airport)
0.02
0.01
0.02
0.03
0.03
NLCD 1992 Cat. 21
Cultivated Crops (Non-airport)
0.03
0.014
0.04
0.2
0.2
Estimated
90
Woody Wetlands
0.4
0.3
0.5
0.5
0.5
NLCD 1992 Cat. 91
91
Palustrine Forested Wetland
0.4
0.3
0.5
0.5
0.5
NLCD 1992 Cat. 91
92
Palustrine Scrub/Shrub Wetland
0.2
0.1
0.2
0.2
0.2
NLCD 1992 Cat. 92
93
Estuarine Forested Wetland
0.4
0.3
0.5
0.5
0.5
NLCD 1992 Cat. 91
94
Estuarine Scrub/Shrub Wetland
0.2
0.1
0.2
0.2
0.2
NLCD 1992 Cat. 92
95
Emergent Herbaceous Wetland
0.2
0.1
0.2
0.2
0.2
NLCD 1992 Cat. 92
96
Palustrine Emergent Wetland (Persistent)
0.2
0.1
0.2
0.2
0.2
NLCD 1992 Cat. 92
97
Estuarine Emergent Wetland
0.2
0.1
0.2
0.2
0.2
NLCD 1992 Cat. 92
98
Palustrine Aquatic Bed
0.05
0.05
0.05
0.05
0.05
Estimated
99
Estuarine Aquatic Bed
0.05
0.05
0.05
0.05
0.05
Estimated
1 Values are listed for the following seasonal categories: 1 - Late autumn after frost and harvest; or winter with
no snow; 2 - Winter with continuous snow on ground; 3 - Transitional spring with partial green coverage or
short annuals; 4 - Midsummer with lush vegetation; 5 - Autumn with unharvested cropland
2 Surface roughness lengths for categories 21-24 that make up the Developed class of categories in the annual
NLCD are calculated as a weighted geometric mean of a combination of the following original 1992 NLCD
categories (see applied weights in tables below):
® High Intensity Residential (22)
® Bare Rock/Sand/Clay (31)
• Mixed Forest (43)
• Urban/Recreational Grasses (85)
1992 NLCD Values are italicized on gray background
Roughness length assigned to 2001. 2006. 2011 categories on orange background
Applied weights are on yellow background
AP = Airport, NonAP
= Non-airport, GM = Geometric Mean
Season 1 -
Late autumn or Winter without snow:
Season 2-
Winter with sr
1992 Cat:
22
H
43
85
1992 Cat:
22
31
43
85
2001 Cat
1
0.05
0.9
0.01
GM
2001 Cat
1
0.05
0.8
0.005
GM
21 AP"
0.05
0.05
0.05
0.85
0.017
21 AP
0.05
0.05
0.05
0.85
0.009
21 NonAP"
0.05
0.05
0.1
0.8
0.021
21 NonAP
0.05
0.05
0.1
0.8
0.012
22 AP
0.05
0.3
0.05
0.6
0.026
22 AP
0.05
0.3
0.05
0.6
0.017
22 NonAP
0.3
0.05
0.1
0.55
0 068
22 NonAP
0.3
0.05
0.1
0.55
0.046
23 AP
0.1
0.55
0.05
0.3
0.048
23 AP
0.1
0.55
0.05
0.3
0.039
23 NonAP
0.6
0.05
0.1
0.25
0.269
23 NonAP
0.6
0.05
0.1
0.25
0.224
24 AP
0.1
0.8
0.05
0.05
0.072
24 AP
0.1
0.8
0.05
0.05
0.069
24 NonAP
0.85
0.05
0.05
0.05
0.680
24 NonAP
0.85
0.05
0.05
0.05
0.653
Season 3 -
Transitional SDrina
Season 4 -
Midsummer with lush veaetation:
1992 Cat:
22
31
43
85
1992 Cat:
22
31
43
85
2001 Cat
1
0.05
1.1
0.015
GM
2001 Cat
1
0.05
1.3
0.02
GM
21 AP
0.05
0.05
0.05
0.85
0.024
21 AP
0.05
0.05
0.05
0.85
0.031
21 NonAP
0.05
0.05
0.1
0.8
0.030
21 NonAP
0.05
0.05
0.1
0.8
0.039
22 AP
0.05
0.3
0.05
0.6
0.033
22 AP
0.05
0.3
0.05
0.6
0.039
22 NonAP
0.3
0.05
0.1
0.55
0.086
22 NonAP
0.3
0.05
0.1
0.55
0.103
23 AP
0.1
0.55
0.05
0.3
0.055
23 AP
0.1
0.55
0.05
0.3
0.060
23 NonAP
0.6
0.05
0.1
0.25
0.304
23 NonAP
0.6
0.05
0.1
0.25
0.332
24 AP
0.1
0.8
0.05
0.05
0.074
24 AP
0.1
0.8
0.05
0.05
0.076
24 NonAP
0.85
0.05
0.05
0.05
0.701
24 NonAP
0.85
0.05
0.05
0.05
0.717
Season 5 -
Autumn with unharvested cropland
1992 Cat:
21
43
85
2001 Cat
1
0.05
1.3
0.015
GM
* GM =EXP(LN(SB$3)
*B4+LN($C$3)*C4+LN($D$3)*D4+LN($E$3)*E4)
21 AP
0.05
0.05
0 05
0.85
0.025
21 NonAP
0.05
0.05
0.1
0.8
0.031
22 AP
0.05
0.3
0.05
0.6
0.033
22 NonAP
0.3
0.05
0.1
0.55
0.088
23 AP
0.1
0.55
0.05
0.3
0.055
23 NonAP
0.6
0.05
0.1
0.25
0.309
24 AP
0.1
0.8
0.05
0.05
0.075
24 NonAP
0.85
0.05
0.05
0.05
0.707
6-12
-------
7,0 Appendix C. Alphabetical keyword reference
This appendix provides an alphabetical listing of all of the keywords used by the
AERSURFACE program. Each keyword is identified as to the pathway for which it applies, the
keyword type: mandatory (M), optional (O) or conditional (C), and either repeatable (R) or non-
repeatable (N), 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 3.0 or the Functional Keyword/Parameter Reference in
Section 8.0.
7-1
-------
Table 7-1. All Primary Keywords Available in AERSURFACE
Keyword
Path
Type
Keyword Description
ANEM HGT
CO
0 - N
Anemometer height (for ZOEFF roughness option)
CNPYGRID
OU
0 - N
Debug file - Canopy data grid
CNPYTIFF
OU
0 - N
Debug file - Canopy debug file containing TIFF tag and GeoKey
values
CENTERLL*
CO
M-N
Met tower coordinates in latitude and longitude
CENTERXY*
CO
M-N
Met tower location in UTM coordinates
CLIMATE
CO
0 - N
Climate and moisture parameters of study area
DATAFILE
CO
M-R
Land cover input datafiles (including impervious and canopy data)
DEBUGOPT
CO
0 - N
Debug options for debug files
EFFRAD
OU
0 - N
Table of effective radius values by sector and month
FREQ SECT
CO
0 - N
Indicates temporal frequency of surface values, number of roughness
sectors and whether surface roughness adjustments are made and if they
vary by sector.
FINISHED
ALL
M-N
Identifies the end of pathway inputs
MPRVGRID
OU
0 - N
Debug file - Impervious data grid
MPRVTIFF
OU
0 - N
Debug file - Impervious debug file containing TIFF tag and GeoKey
values
NLCDGRID
OU
0 - N
Debug file - Land cover data grid
NLCDTIFF
OU
0 - N
Debug file - Land cover debug file containing TIFF tag and GeoKey
values
OPTIONS
CO
O-N
Processing options
RUNORNOT
CO
M-N
Indicates to stop execution after checking control file setup or continue
processing if not errors found
SFCCHAR
OU
M-N
Averaged surface characteristic values formatted for input to AERMET
SEASON
CO
0 - R
Used to reassign months to seasons to override default
assignments
SECTOR
CO
C-R
Define roughness sectors and indicate if lower or higher values should
be used.
STARTING
ALL
M-N
Identifies the end of pathway inputs
TITLEONE
CO
M-N
First line of title for output
TITLETWO
CO
O-N
Optional second line of output title
ZORADIUS
CO
O-N
Fixed radius for averaging roughness (for ZORAD roughness option)
* User must specify either CENTERXY or CENTERLL.
Type: M - Mandatory N - Non-Repeatable
O - Optional R - Repeatable
C - Conditional
7-2
-------
8,0 Appendix D. Functional keyword/parameter reference
This appendix provides a functional reference for the keywords and parameters used by the
control for the AERSURFACE program. 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
preprocessor. The pathways used by the preprocessor are as follows, in the order in which they appear
in the control file and in the tables that follow:
CO - for specifying overall job COntrol options; and
OU - for specifying OUtput file information.
The pathways and keywords are presented in the same order as in the Detailed Keyword Reference in
Section 3.0.
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 presents the parameters for each keyword in the order in which they should appear in the control
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 (they are underlined in the table). 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 preprocessor 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.
8-1
-------
Table 8-1. Description of Control Pathway Keywords
CO Keywords
Type
Keyword Description
STARTING
M-N
Identifies the start of pathway inputs
TITLEONE
M-N
First line of title for output
TITLETWO
O-N
Optional second line of title for output
OPTIONS
O-N
Processing options
DEBUGOPT
O-N
Debug options for debug files
CENTERXY*
M-N
Met tower location in UTM coordinates
CENTERLL*
M-N
Met tower coordinates in latitude and longitude
DATAFILE
M-R
Land cover input datafiles (including impervious and canopy data)
ZORADIUS
O-N
Fixed radius for averaging roughness (for ZORAD roughness option)
ANEM HGT
O-N
Anemometer height (for ZOEFF roughness option)
CLIMATE
O-N
Climate and moisture parameters of study area
FREQ SECT
M-N
Indicates temporal frequency of surface values, number of roughness
sectors and whether surface roughness adjustments are made and if they
vary by sector.
SECTOR
C-R
Define roughness sectors and indicate if lower or higher values should be
used.
SEASON
0 - R
Used to reassign months to seasons to override default assignments
RUNORNOT
M-N
Identifies whether to run program or process setup information
onlv
FINISHED
M-N
Identifies the end of pathway inputs
* User must specify either CENTERXY or CENTERLL.
Type: M - Mandatory N - Non-Repeatable
O - Optional R - Repeatable
C - Conditional
8-2
-------
Table 8-2. Description of Control Pathway Keywords and Parameters
Keyword
Parameters
TITLEONE
titlel
where:
titlel
First line of title for output, character string of up to 200
characters
TITLETWO
titlel
where:
titlel
Second line of title for output, character string of up to 200
characters
OPTIONS
PRIMARY ZORAD
or or
SECONDARY ZOEFF
where:
PRIMARY
SECONDARY
ZORAD
ZOEFF
Site processed for primary surface characteristics and will generate
keywords for primary values for AERMET (default)
Site processed for secondary surface characteristics and will
generate keywords for secondary values for AERMET.
Calculates the average roughness from the meteorological tower
out to a default radial distance of 1 km. (default)
Research grade method for calculating roughness that estimates
fetch based the growth of the IBL due to changes in roughness
downwind. Average roughness is computed over the estimated
fetch, approaching the meteorological tower.
DEBUGOPT
EFFRAD and/or GRID and/or TIFF or ALL
where:
EFFRAD
GRID
TIFF
ALL
Generates file containing the effective radius for surface roughness
computed for each sector/month (only applicable for ZOEFF option
specified with the OPTIONS keyword)
Generates grid file of land cover data and, if applicable, separate
files for impervious, and canopy data, displaying the 10x10 km grid
of values extracted from each GeoTIFF data file
Generates debug file containing a list of all TIFF tags, GeoKeys,
and associated values read from the land cover file and, if
applicable, separate files for impervious and canopy data files
Generates all debug files listed above without having to list each
debug option separately
8-3
-------
CENTERXX
easting northing utm zone datum
where:
easting
northing
utm zone
datum
UTM easting coordinate in meters
UTM northing coordinate in meters
UTM zone entered as a positive integer
Geodetic datum on which coordinates are based. The datum should
be entered using one of the following secondary keywords: NAD27
or NAD83. which refer to the North American 1927 datum and the
North American 1983 datum, respectively. NAD83 should also be
used for coordinates referenced to the GRS80 and WGS84 datums
since the small differences are inconsequential for the purposes of
AERSURFACE.
User must specify either CENTERXY or CENTERLL.
CENTERLL
latitude longitude datum
where:
latitude
longitude
datum
Latitude in decimal degrees (Northern hemisphere = positive value)
Longitude in decimal degrees (Western hemisphere = negative value)
Geodetic datum on which coordinates are based. The datum should be
entered using one of the following secondary keywords: NAD27 or
NAD83. which refer to the North American 1927 datum and the
North American 1983 datum, respectively. NAD83 should also be
used for coordinates referenced to the GRS80 and WGS84 datums
since the small differences are inconsequential for the purposes of
AERSURFACE.
User must specify either CENTERXY or CENTERLL.
DATAFILE
data type pathJilename
8-4
-------
where:
data type
Type of data and year the data represent. Data type includes:
NLCD for land cover, MPRV for impervious, and CNPY for
canopy. Valid release years include: 1992, 2001, 2006, 2011,
2013, 2016, 2019, and 2021.The following are examples of
valid secondary keywords for data type:
NLCD2021: 2021 NLCD land cover
MPRV2021: 2021 percent impervious
CNPY2021: 2021 percent canopv
path Jilename
User-defined path and filename. The combined path and filename are
limited to 200 characters and should be enclosed in quotes ("") if
either the path or filename includes spaces.
ZORADIUS
radius
where:
radius
Distance from the meteorological tower in kilometers over which the
surface roughness length will be averaged
ANEM HGT
anem ht (iblJactor)
where:
anem ht
Height, in meters, at which the wind measurements are taken at the
site that will be processed. The accepted value for anem ht ranges
from 1.0 meter to 100.0 meters. Only applicable for the ZOEFF
option for calculating roughness.
(iblJactor)
Optional unitless parameter, ranging from 5.0 - 10.0, used to compute
the reference height of the IBL. The IBL reference height is the
product of the anem ht and the iblfactor. The default IBL factor is
6.0. The IBL factor is an experimental value for which a
recommended value has not yet been established.
8-5
-------
CLIMATE
sfc moisture snow cover arid condition
where:
sfc moisture
Surface moisture based on precipitation amounts for the period
that will be modeled, relative to the previous 30-year
climatoloaical record for the reaion. Valid entries: WET. DRY. or
AVERAGE for AVG) (default = AVERAGE)
snow cover
Site experienced continuous snow cover within at least on month
during the winter. Valid entries: SNOW or NOSNOW (default =
NOSNOW)
arid condition
Enter ARID (desert-like) or NONARID (default = NONARID).
NONARID is an invalid entrv in combination with continuous
snow cover (SNOW)
FREQ SECT
frequency number sectors roughnessJlag
where:
frequency
Period of time for which the surface characteristics are calculated,
valid entries: ANNUAL. SEASONAL, or MONTHLY.
number sectors
Integer number of roughness sectors that will be defined using the
SECTOR keyword. Sectors are only applicable to roughness
length. The number of sectors can range from 1 to 12 or 16.
AERMET allows a maximum of 12 sectors, but AERSURFACE
can calculate roughness for 16 sectors which can be useful for
comparing roughness lengths to a standard 16-direction wind rose
plot. When 16 sectors are specified, AERSURFACE results
cannot used as input to AERMET.
roughness Jlag
Indicates whether AERSURFACE will apply lower or higher
roughness values to all wind sectors, or if the sectors vary. Valid
entries. LOWZO. HIGHZO. VARYZO. AP. NONAP. or VARYAP
where: LOWZO/AP indicates lower roughness values will be
applied to all sectors; HIGHZO/NONAP indicates that higher
values will be applied; and VARYZO/VARYAP informs
AERSURFACE to treat each sector separately based on how the
sector is identified with SECTOR keyword.
8-6
-------
SECTOR
sector index start dir end dir roughness flag
where:
sector index
start dir
end dir
roughness Jlag
Links a specific sector to a set of site characteristics and should be
entered as consecutive integers beginning with the number 1.
Starting direction of the sector in whole degrees. Considered part of
the sector.
Ending direction of the sector in whole degrees but excluded from
sector.
Sectors should be defined in a clockwise manner and must cover the
full 360° circle around the meteorological tower without gaps or
overlap, (i.e., They must be defined so that the end of one sector
corresponds to the beginning of another. When 2-12 sectors are
defined, each sector must be a minimum of 30°. 16 sectors must each
be 22.5°. When 1,8, 12 or 16 is entered for the number of sectors on
the FREQ SECT keyword, the SECTOR keyword may be omitted,
and default sectors used unless VARYAP is entered as the
airport Jlag attribute for the FREQ SECT keyword.
Identifies whether the individual sector should be processed using
lower or higher related roughness length values. This attribute is
required when the secondary kevword VARYZO/VARYAP is entered
as the roughness Jlag attribute for the FREQ SECT keyword which
means each sector will be assigned individually. When that is the
case, the roughness Jlag should be specified using the secondary
kevword LOWZO/AP to indicate lower surface roughness values or
HIGHZO/NONAP to indicate higher roughness values.
SEASON
season months
where:
season
months
Secondary keyword that identifies one of five seasonal definitions:
SUMMER. AUTUMN. WINTERNS. WINTERWS. SPRING.
Space-delimited list of integer months assigned to the season. Valid
entries are 0-12, where 1 = Jan, 2 = Feb ... 12 = Dec. Zero (0)
indicates no months are being reassigned to the season. A season may
be specified only once. The months reassigned to a season should be
listed on a single record separated by at least one space. A month can
only be assigned to one season. It is only necessary to specify the
seasons/months that are to be reassigned. If 0 is entered for a season,
then default assignments will be used for any month that is not listed
for a different season.
RUNORNOT
RUN or NOT
where:
RUN
NOT
Indicates to run full preprocessor calculations.
Indicates to process setup data and report errors, but to not run full
preprocessor calculations.
8-7
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Table 8-3. Description of Output Pathway Keywords
OU Keywords
Type
Keyword Description
STARTING
M-N
Identifies the start of output pathway inputs
SFCCHAR
M-N
Averaged surface characteristic values formatted for input to AERMET
EFFRAD
O-N
Table of effective radius values by sector and month
NLCDGRID
O-N
Land cover data grid
MPRVGRID
O-N
Impervious data grid
CNPYGRID
O-N
Canopy data grid
NLCDTIFF
O-N
Land cover debug file containing TIFF tag and GeoKey values
MPRVTIFF
O-N
Impervious debug file containing TIFF tag and GeoKey values
CNPYTIFF
O-N
Canopy debug file containing TIFF tag and GeoKey values
FINISHED
M-N
Identifies the end of output pathway inputs
Table 8-4. Description of Output Pathway Keywords and Parameters
Keyword
Parameters
SFCCHAR
path Jilename
EFFRAD
NLCDGRID
MPRVGRID
CNPYGRID
NLCDTIFF
MPRVTIFF
CNPYTIFF
where:
path Jilename
User-defined path and filename. The combined path and filename is limited to
200 characters and should be enclosed in quotes ("") if either the path or
filename includes spaces.
-------
9.0 Appendix E: Implementation of ZOEFF Option in AERSURFACE, Version 20060
9.1 Method
A research grade method (ZOEFF) for computing an effective surface roughness length, Zo,
using land cover data from the National Landcover Database (NLCD) was first implemented in
19039 DRFT and carried forward in version 20060 for further evaluation. The method used to
compute roughness in prior versions has been retained as the default option and is hereon referred to as
the ZORAD option. The default method (ZORAD) computes Zo as an inverse distance weighted
geometric mean of the representative roughness values extracted from the NLCD for a default fixed
upwind radial distance of 1 kilometer, relative to the location of the meteorological measurement site.
Zo, can be calculated for multiple wind sectors to account for substantial directional differences in land
cover type.
The experimental method, ZOEFF, determines the upwind distance from the meteorological
tower, or fetch, over which to compute an effective roughness value, rather than using a fixed radial
distance. The method is based on the distance required to grow the internal boundary layer (IBL) to
some defined height at the measurement tower due as changes in surface roughness are encountered as
the air flows toward the tower. A final effective roughness length is then calculated over the derived
fetch. As with the original default method, Zo can be computed for multiple wind sectors. The
estimated fetch for which the effective roughness is computed will vary by sector.
9.2 Scientific Basis
The growth of the IBL is influenced, in part, by the mechanical forcing due to friction caused
by the roughness of the earth's surface. This method (ZOEFF) for calculating effective roughness is
based on the cumulative growth of the IBL as air flow encounters surface roughness elements as it
approaches the tower.
9-1
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This method was adapted from a model coding abstract (MCA) and MATLAB code developed
by Dr. Akula Venkatram2, based on methods proposed by Miyake (1965) and Wiering (1993), to
estimate surface roughness as a function of the growth of the internal boundary layer (IBL). A review
of methods for estimating the height of the IBL, which discusses Miyake's related work, was
performed by Garratt (1990). Venkatram's original MCA (edited) is included as Section 10.0 of this
User's Guide.
As described by Wieringa (1993) and stated in Venkatram's MCA and Garratt (1990), the
growth of the IBL (h), with distance (x) over a constant roughness, can be described by the following
equation:
dh u* k 4
where, Zo is the surface roughness, k\s 0.4 (von Karman constant), w* is the surface friction velocity,
and U(h) is the mean wind speed at the height of the IBL.
As described in Venkatram's MCA, integrating Equation 4 between two points, x* and x, /,
produces the following equation for the growth of the IBL and can be used to calculate the growth of
the IBL between two points based on the average roughness and distance between them:
hi+1 (ln (P^-) ~1)= hi(ln (v~L~) - A + k(xi+1 ~ *i) 5
\ \z0 avgj J \ \z0 avgj J
where Zoavg is the average roughness between the two points x, and x, /. (Whereas Venkatram used a
simple arithmetic mean of the two roughness values at x* and x, /, the implementation of this method
(ZOEFF) in AERSURFACE uses a geometric mean of the two roughness values for consistency with
2 Dr. Akula Venkatram is a professor at the University of California, Riverside in the Department of Mechanical
Engineering. Venkatram was an original member of the American Meteorological Society/Environmental Protection Agency
Regulatory Model Improvement Committee (AERMIC) during the development and promulgation of AERMOD.
9-2
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the default method in AERSURFACE version 13016, retained in this version (20060) as the ZORAD
method).
By setting a target IBL height, href, at the measurement site based on some multiple of the measurement
height and setting a fixed distance to represent delta x over which each Zoavg is computed, the change in
the IBL height can be calculated for each delta x to determine the distance, xrad, required for the
cumulative growth for each delta x from an initial h = Zo at xrad- The current implementation uses a
default value for /?,L/ that is equal to 6 times the anemometer height. This factor can be changed through
user input.
Once xrad has been determined, per Venkatram, the effective roughness (Zoefi) for the sector is
computed over the distance xrad as the solution to the following equation:
9.3 Implementation
The horizontal grid resolution of the land cover data processed by AERSURFACE is 30 meters.
To implement the ZOEFF method for determining Zoe/f.; AERSURFACE first divides the land cover
into concentric rings out to an initial radial distance of 5 km from the meteorological tower, with each
ring having a depth equal to the horizontal grid resolution of the data (30 meters). The rings are then
subdivided by sector as shown in Figure 9-1.
6
9-3
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Wind Sector
Concentric Rings
(depth = 1 grid cell, 30 m)
Met Tower
Figure 9-1. Concentric Rings Defined around Meteorological Tower to
Calculate IBL Growth
As with previous versions of AERSURFACE, seasonal roughness values have been assigned to
each land cover category and are stored in a data table in the AERSURFACE source code. Monthly
values of Zo are computed for each ring segment within each sector using the seasonal lookup tables
and the values associated with the season to which each month is assigned. The monthly Zo value for a
ring segment is computed as an inverse distance weighted geometric mean of the roughness values
associated with each of the grid cells that make up the ring segment based on the distance of each grid
cell from the meteorological tower. The inverse distance weighted geometric mean is computed using
equation 1 in Section 2.4.1.1 for the default ZORAD option but limited to the grid cells that comprise
the ring segment. Like the ZORAD option, an inverse distance weighted approach is used because the
width of a sector increases with distance from the measurement site. Thus, ring segments farther from
the met tower are comprised of more grid cells than ring segments closer to the tower. If a direct area
weighted approach were used, the land cover farther from the site would receive a higher effective
weight than land cover closest to the site when the fetch is derived as described next.
Using Equation 5 above, the amount of fetch required for the cumulative growth of the IBL to a
default height of six (6) times the height of the anemometer at the tower location is determined. The
value, six (6), is referred to as the IBL factor and can be set by the user. The default value for the IBL
factor is based on Wieringa's "roughness blending height" of 60 m (Wieringa, 1976) given that 10 m is
a common anemometer height at NWS/FAA weather stations. As Venkatram points out in his MCA
and is discussed by Wierenga (1993), Miyake's research was based on surface releases when the
9-4
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vertical plume spread is of the order of href. The IBL factor may need to be varied based on the release
height or anemometer height.
The fetch (;xrad) required to grow the IBL to a target height {href) is determined by summing
smaller changes in the height of the IBL that are associated with fixed, shorter lengths of assumed
homogeneous roughness based on the previously computed Zo values for the individual ring segments
within a sector. Within a user-defined sector, the fetch is first estimated by starting at the tower location
and summing incremental IBL heights across the concentric ring segments out from the tower. The
geometric mean of the roughness (Zoavg) of two adjacent rings is computed and treated as the
homogenous surface and distance over which to compute an incremental change in the height of the
IBL. The distance is taken to be from the center of one ring segment to the center of the adjacent ring,
30 meters. This occurs outward across the concentric rings until the sum of the individual heights
equals or exceeds href If href is not reached within a 5 km radial distance from the tower (which can
occur for very long fetches over a very smooth surface), the estimated fetch is limited to 5 km. The
effective roughness is then computed for the sector from the tower out to the distance for this estimated
fetch using equation 6, above.
The fetch (;xrad) is recomputed iterating across the concentric rings going toward the tower,
starting at the distance determined from the first set of iterations and stopping at the location of the
meteorological tower. If the height of the IBL at the tower is computed to be higher than the href then
the fetch is recomputed starting one ring closer to the tower than the original estimated fetch. If the
computed height of the IBL at the tower is lower than the target IBL, the fetch is recomputed starting
one ring width farther than the original estimated fetch. An interpolated distance based on the target
IBL height at the tower is taken as xrad iterating across the rings toward the tower. The average
effective roughness is then computed for the sector for this new value of xrad using equation 6, above.
The final value for Zoeff is computed as the simple arithmetic mean of the two calculated effective
roughness values based on the calculated for the distance xraditerating outward from the tower and the
calculated distance xrad iterating over the rings toward the tower.
9-5
-------
These steps are repeated to compute monthly values of Zoefffor each user-defined sector. Annual
and seasonal values are then computed from the monthly values based on the temporal frequency
specified by the user in the control file.
9-6
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10.0 Appendix F: Venkatram Model Coding Abstract - Estimating Effective Roughness
If wind speed is measured on a tower located in a spatially inhomogeneous area, we need an
effective roughness height to estimate the surface friction velocity and other micrometeorological
variables. This effective roughness should represent the combined effect of the roughness elements
that the boundary layer encounters on its way to the measurement location. A heuristic approach to
this calculation is based on estimating the combined effect of the internal boundary layers associated
with the changes in the roughness as the air travels over a spatially inhomogeneous path. If we assume
that the roughness is constant between two points along this path, the change in the internal boundary
layer height, h, between these two points is given by (Miyake, 1965 quoted in Wieranga, BLM, 63,
323-363, 1993):
On estimating effective roughness
Akula Venkatram
December 24, 2009
7
dx U(h) ln fh_\
dx U (/i)
Integrating this equation between points, Xi and Xi+i, gives
8
where
Z0avg= (zo (0+ z0 (i +1))/ 2.
9
10-1
-------
This implicit equation can be used compute the height of the internal boundary layer as a function of
distance from the measurement location.
At the measurement location, the combined internal boundary height has a vertical structure
that reflects the roughness elements contributing to its growth. The lowest part of the boundary layer is
representative of the roughness elements closest to the measurement location, and the upper part of the
boundary layer reflects the roughness elements furthest from the location. This suggests calculating h
with the initial hi = zoi and then stopping the integration when the internal boundary height reaches a
multiple, p, of Zmeas given by href= fizmeas. The radius of influence, xrad, is the distance at which this
boundary layer height reaches href.
Then, the effective roughness is the solution of the integral of Equation 7, assuming that an
effective constant roughness, zoeff, applies to the region 0 to xrad.
This equation can be solved numerically to yield zoeff.
It is clear that p is a critical parameter that needs to be determined by comparing the computed
effective zo with a value inferred from simultaneous measurements of surface friction velocity and
wind speed using sonic anemometers. Then,
The computed zoeff is likely to apply only to surface releases, and only when the vertical plume
spread is of the order of href. If we want to estimate dispersion from an elevated source, we might have
to calculate a zoefffor a href corresponding to a multiple of the release height. This means that zoeff w\\
vary with source height.
10
•*
11
10-2
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11.0 Appendix G: Inter-comparison of AERSURFACE
An inter-comparison of values of surface roughness length, estimated using AERSURFACE
version 20060, is presented, as well as a comparison of corresponding AERMOD results for several
different source types and configurations. This inter-comparison was first presented as Appendix G of
the AERSURFACE User's Guide (EPA, 2019a) for version 19039 DRFT of AERSURFACE in which
meteorological processing was performed with AERMET version 18081 and dispersion modeling was
performed with AERMOD version 18081. The inter-comparison has been updated using
AERSURFACE version 20060 and version 19191 of AERMET and AERMOD. The original inter-
comparison was performed using the 2011 edition of the 2001 National Land Cover Database (NLCD).
With the generation and release of the 2016 NLCD by the Multi-Resolution Land Characteristics
(MRLC) Consortium, led by the US Geological Survey (USGS), the 2001 NLCD land cover and
percent impervious data were also updated with corrections and refinements. Those updates were
carried forward through subsequent updates of the 2006 and 2011 NLCD data years released as new
versions at the time of the release of the 2016 NLCD. The update to the 2001 NLCD did not include an
update to the 2001 percent tree canopy data; therefore, the 2001 NLCD that is currently available from
the MRLC does not include 2001 percent tree canopy data. For consistency, the inter-comparison
presented in this appendix to the AERSURFACE User's Guide for version 20060 is also based on the
2011 edition of the 2001 NLCD which was used for the inter-comparison presented in Appendix G to
the AERSURFACE User's Guide specific to version 19039 DRFT. Unless otherwise stated,
references to the 2001 NLCD are meant to refer to the 2011 edition of the 2001 NLCD. Also included
in this update to the inter-comparison is a comparison of surface characteristic values estimated using
the 2016 NLCD with those estimated using the 2011 edition of the 2001 NLCD.
Surface characteristics were estimated using the two AERSURFACE options for estimating
surface roughness length (ZORAD and ZOEFF) and by varying combinations of input data (i.e., land
cover, percent impervious, and percent canopy). The comparisons that are presented below are not an
evaluation of the updated AERSURFACE tool. Rather, because version 20060, like version
19039 DRFT, includes a research grade method (ZOEFF) for estimating surface roughness length and
the use of supplemental percent impervious and percent canopy data beginning with the release of the
11-1
-------
2001 NLCD, this comparison is a limited demonstration of differences in results using the different
roughness options and varying the NLCD input data. Estimated values of albedo and Bowen ratio are
unaffected by the choice of option for estimating surface roughness length or the use of the impervious
and canopy data; therefore, albedo and Bowen ratio are not presented as part of this comparison.
11.1 AERSURFACE Scenarios and Meteorological Data Processing with AERMET
Three NWS/FAA meteorological sites were selected for this comparison, including: Hartsfield-
Jackson Atlanta International Airport (ATL), Baton Rouge Metropolitan Airport (BTR), and Raleigh-
Durham International Airport (RDU). Because the version of the 2001 NLCD (2011 edition) that was
available at the time this comparison was first performed included land cover, impervious, and canopy
data, this comparison primarily uses the 2011 edition of the 2001 NLCD. Based on historical satellite
imagery, BTR appears to have experienced only a small amount of change in land use from 1992 to
2001 in the near proximity to the tower. Thus, additional comparisons of surface roughness values
estimated using the ZORAD and ZOEFF options with the 1992 NLCD land cover data were performed
to show differences in results between the two NLCD datasets (1992 and 2001). The 1992 NLCD land
cover data combined with the default ZORAD is equivalent to running AERSURFACE version 13016
with land cover data only from the 1992 NLCD.
As discussed in Section 2.1, the land cover classification scheme changed from the 1992 to the
2001 NLCD for certain land cover categories. These changes prompted adding the capability to
AERSURFACE to supplement land cover with impervious and canopy data beginning with the 2001
NLCD.
For each station location, surface characteristic values were estimated for the AERSURFACE
scenarios listed in Table 11-1. Table 11-2 lists the additional AERSURFACE scenarios for which
surface characteristic values were estimated for BTR using the 1992 NLCD.
Table 11-1. 2001 NLCD (2011 Edition) AERSURFACE Scenarios for ATL, BTR, and RDU
Roughness Option
2001 NLCD (2011 Edition)
Scenario Name
Data Inputs
11-2
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ZORAD
Land Cover
Percent Impervious
Percent Canopy
2001 -LC-IMP-CAN-ZORAD
Land Cover
Percent Impervious
2001 -LC-IMP-ZORAD
Land Cover
Percent Canopy
2001-LC-CAN-ZORAD
Land Cover
2001-LC-ZORAD
ZOEFF
Land Cover
Percent Impervious
Percent Canopy
2001-LC-IMP-CAN-ZOEFF
Land Cover
Percent Impervious
2001-LC-IMP-ZOEFF
Land Cover
Percent Canopy
2001 -LC-CAN -ZOEFF
Land Cover
2001 -LC-ZOEFF
Table 11-2. 1992 NLCD AERSURFACE Scenarios for BTR
Roughness Option
1992 NLCD Data Inputs
Scenario Name
ZORAD
Land Cover
1992-LC-ZORAD
ZOEFF
Land Cover
1992-LC-ZOEFF
Seasonal surface characteristic values were estimated using AERSURFACE for each scenario
in Table 11-1 and Table 11-2, assuming average surface moisture, a non-arid climate, and without
continuous snow during the winter. The center of the study area was defined as the location of the
meteorological tower associated with the ASOS station at each airport. Wind sectors were defined for
each site to estimate surface roughness length, based on changes in roughness within a radial distance
out to 1 km from the meteorological tower. Sectors were individually identified as either airport or non-
airport based on visual inspection of satellite imagery. Sectors that consisted primarily of runways or
open parking lots were treated as an airport. Sectors that consisted primarily of buildings or vegetation
were treated as non-airport sectors. (Refer to Sections 2.3.2, 2.4.1.3 and 3.2.9 for more discussion on
the characterization of sectors as airport or non-airport.) The coordinates of the meteorological tower
11-3
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for each station, sector definitions, and whether airport or non-airport reference values were used to
compute surface roughness length, by sector, are listed in Table 11-3. Figure 11-1 through Figure 11-3
show 2001 satellite imagery from Google Earth for each of the airport sites and identifies the
10x10 km area for which albedo and Bowen ratio are estimated and the circular area around the
tower, out to 1 km, including the individual wind sectors for which roughness length is estimated.
11-4
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Table 11-3. NWS/FAA Meteorological Tower Location and Wind Sector Definitions
NWS/FAA
Station
Latitude
Longitude
Sector
Reference Surface
Values
ATL
33.629691
84.442249
o
0
1
Lh
o
Non-airport
145°-270°
Non-airport
270° - 90°
Airport
BTR
30.537804
-91.146804
50°-210°
Airport
210°-280°
Airport
280°-50°
Non-Airport
RDU
35.892300
-78.781900
30° - 60°
Non-airport
60° - 225°
Airport
225°-30
Non-airport
11-5
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Figure 11-1. ATL 10 x 10 km Area and 1 km Radius with Wind Sectors
11-6
-------
O 1km Radius with Sectors
~ BTR Meteorological Tower ~ 10 x 10 km Area
Figure 11-2. BTR: 10 x 10 km Area and 1 km Radius with Wind Sectors
11-7
-------
"fr RDU Meteorological Tower ~ 10 x 10 km Area o lkm Radius with Sectors
K/i*
-
If, .
TS-* v
f.-r
I-
,, _yy, ~v
¦T «• *r
#N Wff*
«J# 32° &,!
t. A ¦ "225 jM*
WSfSS^
60° 1k
V , * /»•
hxyr ¦ m
• • V ¦*
' *•• »)•., \
gur^r-
V^* - -Jt
• • #,r
V I
.<1 K
'¦^y^naoedt^Bdsat / Copernicus
pvt > S.
« . npn
*-rr>
W 0 ¥ .
7y • V
>/<«. "•/
• Imagery Date: 12/30/2001 lat—35.894598° Ion -78:803387° elev 105 m eye alt 18.63.km Q
Figure 11-3. RDU: 10 x 10 km Area and 1 km Radius with Wind Sectors
11-8
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Figure 11-4 through Figure 11-10 show the land cover, percent impervious, and percent canopy
data from the 2001 NLCD (2011 edition) for each of the three sites and the 1992 NLCD land cover for
BTR.
11-9
-------
ATL 2001 NLCD Land Cover
¦fr ATLMeteorologicalTower
~ 10 x 10 km Area
0 1 km Radius with Sectors
2001, 2006, 2011 NLCD Land Cover Classification
1 111 Open Water
I 12 Perennial Ice/ Snow
121 Developed. Open Space
] 22 Developed. Low Intensity
123 Developed. Medium Intensity
^¦24 Developed, High Intensity
[ ] 31 Barren Land (Rock/Sand/Clay)
I ] 41 Deciduous Forest
42 Evergreen Forest
] 43 Mixed Forest
f 51 Dwarf Scrub*
52 Shrub/Scrub
] 71 Grassland/Herbaceous
72 Sedge/Herbaceous*
[ 73 Lichens*
| j 74 Moss*
I 181 Pasture/Hay
H 82 Cultivated Crops
90 Woody Wetlands
95 Emergent Herbaceous Wetlands
* Alaska only
Figure 11-4. 2001 NLCD (2011 Edition) Land Cover for ATL
11-10
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ATL 2001NLCD Percent Impervious ATL 2001NLCD Percent Canopy
0% 50% 100% 0% 50% 100%
Figure 11-5. 2001 NLCD (2011 Edition) Percent Impervious and Percent Canopy for ATL
11-11
-------
BTR 1992 NLCD Land Cover
¦jir BTR Meteorological Tower
~ 10 x 10 km Area
o 1 km Radius with Sectors
NLCD 1992 Land Cover Classification Legend
| 11 Open Water
12 Perennial Ice/Snow
J 21 Low Intensity Residential
| 22 High Intensity Residential
| 23 Commercial/lndustrial/Transportation
31 Bare Rock/Sarvd/Clay
| 32 Quarries/Stop Mines/Gravel Pits
| 33 Transitional Barren
| 41 Deciduous Forest
| 42 Evergreen Forest
43 Mixed Forest
] 51 Shrubland
| 61 Orchards/Vineyards/1 CM her
71 Grassland'Herbaceous
~\ 81 Pasture/Hay
| 82 Row Crops
j 83 Small Grams
84 Fallow
| 85 Urban/Recreational Grasses
91 Woody Wetlands
~j 92 Emergent Herbaceous Wetlands
Figure 11-6. 1992 NLCD Land Cover for BTR
11-12
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•fa BTR Meteorological Tower
~ 10 x 10 km Area
0 1 km Radius with Sectors
2001, 2006, 2011 NLCD Land Cover Classification
H111 Open Water
1 J12 Perennial Ice/ Snow
! 21 Developed. Open Space
122 Developed. Low Intensity
123 Developed. Medium Intensity
¦ 24 Developed, High Intensity
[ ] 31 Barren Land (Rock/Sand/Clay)
i J 41 Deciduous Forest
H 42 Evergreen Forest
[ 43 Mixed Forest
j 51 Dwarf Scrub"
52 Shrub/Scrub
71 Grassland/Herbaceous
72 Sedge/Herbaceous'
73 Lichens'
74 Moss"
81 Pasture/Hay
82 Cultivated Crops
90 Woody Wetlands
195 Emergent Herbaceous Wetlands
* Alaska only
BTR 2001 NLCD Land Cover
Figure 11-7. 2001 NLCD (2011 Edition) Land Cover for BTR
11-13
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Figure 11-8. 2001 NLCD (2011 Edition) Percent Impervious and Percent Canopy for BTR
11-14
-------
RDU 2001 NLCD Land Cover
¦fa RDU Meteorological Tower
~ 10 x 10 km Area
0 1 km Radius with Sectors
2001, 2006, 2011 NLCD Land Cover Classification
11 Open Water
1 112 Perennial Ice/ Snow
i 21 Developed. Open Space
Z] 22 Developed, Low Intensity
H 23 Developed. Medium Intensity
124 Developed. High Intensity
\ 131 Barren Land (Rock/Sand/Clay)
_| 41 Deciduous Forest
42 Evergreen Forest
43 Mixed Forest
151 Dwarf Scrub"
52 Shrub/Scrub
71 Grassland/Herbaceous
72 Sedge/Herbaceous*
73 Lichens'
i 74 Moss"
I 181 Pasture/Hay
¦I82 Cultivated Crops
90 Woody Wetlands
95 Emergent Herbaceous Wetlands
* Alaska only
Figure 11-9. 2001 NLCD (2011 Edition) Land Cover for RDU
11-15
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RDU 2001 NLCD Percent Impervious RDU 2001 NLCD Percent Canopy
0% 50% 100% 0% 50% 100%
Figure 11-10. 2001 NLCD (2011 Edition) Percent Impervious and Percent Canopy for RDU
11-16
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AERMET version 19191 was used to process meteorological data for input to AERMOD for
each of three NWS/FAA station locations (ATL, BTR, and RDU). 2001 surface meteorological
observations for each station were retrieved from the National Centers for Environmental Information
(NCEI), archived in the Integrated Surface Hourly (ISH) format, and paired with concurrent upper air
data from a nearby upper air station. Table 11-4 lists the upper air station that was paired with each
surface station. Concurrent 1-minute ASOS wind data was also retrieved from the NCEI for each
station and processed with AERMINUTE version 15272 to generate hourly wind data for input to
AERMET as a replacement for the hourly wind data extracted from the ISH format. For each surface
station, a separate set of AERMOD-ready 2001 meteorological data files were generated for each of the
AERSURFACE scenarios listed in Table 11-1. An additional set of 2001 meteorological files were
generated using surface characteristic values based on the 1992 NLCD land cover for BTR for the
AERSURFACE scenarios listed in Table 11-2. AERMET was run identically for all scenarios using
only regulatory default options without the adjusted u-star (ADJ U*) option. A minimum wind speed
of 0.5 m/s was used as the minimum threshold applied to the 1-minute ASOS wind data.
Table 11-4. Surface and Upper Air Station Pairings for Meteorological Data Processing
Surface
Station
Upper Air
Station
Upper Air
Station Name
Upper Air
Station City
ATL
FFC
Atlanta Regional
Airport
Atlanta, GA
BTR
SIL
Slidell Airport
Slidell, LA
RDU
GSO
Piedmont Triad
International
Airport
Greensboro, NC
11.2 Emission Sources and AERMOD Setup
One-hour ground-level concentrations of a generic inert pollutant were predicted using
AERMOD version 19191. A separate model run was performed using each of the meteorological
datasets generated for the different AERSURFACE scenarios (Table 11-1 and Table 11-2) for each of
three meteorological surface stations. Emission sources were collocated at the meteorological tower
11-17
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and included in each AERMOD simulation. The emission sources and configurations modeled are
listed in Table 11-5. AERMOD was run using the regulatory default (DFAULT) option.
Table 11-5. Emission Sources
Point Sources
Emission
Release
Exit
Exit
Stack
Source ID
Rate (g/s)
Height (m)
Temperature (K)
Velocity (m/s)
Diameter (m)
PI
100.0
10.0
432.0
11.7
2.4
P2
100.0
35.0
432.0
11.7
2.4
P3
100.0
55.0
432.0
11.7
2.4
P4
100.0
100.0
432.0
18.8
4.6
P5
100.0
200.0
432.0
26.5
5.6
Area Source
Emission
Release
Initial X
Initial Y
Source ID
Rate (g/s-m2)
Height (m)
Dimension (m)
Dimension (m)
A1
0.00001
0.01
100.0
100.0
Volume Source
Emission
Release
Initial
Initial
Source ID
Rate (g/s)
Height (m)
Sigma Y (m)
Sigma
Z (m)
VI
100.0
100.0
14.0
16.0
Concentrations were estimated using a polar receptor grid, centered on the meteorological tower
and extending out to 10 km from the tower. Receptors were defined every 10 degrees around the tower
at the following distances from the tower: 100-meter intervals out to 500 meters; 250-meter intervals
out to 1 km; 500-meter intervals out to 5 km; 1000-meter intervals out to 10 km. The receptor grid for
each station was comprised of 720 receptors. Receptors were processed for each station using
AERMAP version 18081 with 1-arcsecond terrain data from the National Elevation Dataset (NED) to
determine receptor elevations and hill heights.
11-18
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11.3 Inter-comparison of AERSURFACE and AERMOD Results
Figure 11-11, Figure 11-24, and Figure 11-40, at the end of this section, compare estimated
surface roughness lengths across the different AERSURFACE scenarios, seasons, and sectors for ATL,
BTR, and RDU, respectively. Refer to Table 11-1 and Table 11-2 for descriptions of the different
AERSURFACE scenarios for which surface values were generated. Figure 11-12, Figure 11-25, and
Figure 11-41 plot the AERMOD estimated highest 1-hour (H1H) concentrations for each scenario by
source type for each of the three sites, while Figure 11-13, Figure 11-26, and Figure 11-42 plot the
second highest (H2H) estimated 1-hour concentrations.
The remaining figures at the end of this section are collections of scatter plots for each of the
sites that compare AERMOD results by source type for the different scenarios, paired in space.
Specifically, each of the scatter plots compares either the H1H or H2H predicted concentrations at each
receptor, for two of the scenarios. The data points on the scatter plots are colorized based on the
distance from the emission source. For each site, a default "base" scenario is defined. The base
scenario is that scenario that incorporates all three 2001 NLCD data products including land cover,
impervious and canopy data and utilizes the ZORAD roughness option (i.e., LC-IMP-CAN-ZORAD).
The base scenario is compared to each of the other scenarios at the respective site. Similarly, there are
scatter plots that compare each scenario that utilized the ZORAD roughness option to the analogous
scenario that utilized the ZOEFF roughness option (e.g., LC-IMP-CAN-ZORAD vs. LC-IMP-CAN-
ZOEFF)
For each of the three sites, there are generally only small differences (0.01-0.02 meters) in the
roughness length estimated using the research grade ZOEFF option for estimating surface roughness
compared to the default ZORAD option, when comparing scenarios that used the same combination of
NLCD data files (see Figure 11-11, Figure 11-24, and Figure 11-40). This suggests the two methods
for estimating roughness length are comparable to each other. There are, however, greater differences
in the estimated roughness lengths when comparing scenarios that used the same roughness option and
different combinations of NLCD products. The largest differences for the three sites are shown in
Figure 11-11, at ATL, where there is a difference of about 0.2 meters in the roughness values estimated
for Sector 2 during the summer when land cover data are supplemented with both impervious and
11-19
-------
canopy data (2001-LC-IMP-CAN-ZORAD) versus when land cover data are supplemented with
canopy data only (2001-LC-CAN-ZORAD) and similarly, between 2001-LC-CAN-ZORAD and 2001-
LC-ZORAD in which land cover data is not supplemented with either impervious or canopy data.
However, these are the largest differences between estimated values for any sector and season across
the different scenarios for any of the three locations. There is a much smaller difference between 2001-
LC-IMP-CAN-ZORAD which includes impervious and canopy data and 2001-LC-ZORAD which is
based solely on land cover data. For each of the sites, when comparing the scenario that includes both
impervious and canopy data to the scenario that uses only land cover data, the difference in the derived
roughness is generally much less than 0.1 meter.
In general, H1H and H2H concentrations for all scenarios are comparable to the base case (ratio
close to 1.0). ATL resulted in the largest differences in modeled concentrations when comparing
scenarios that used different combinations of NLCD products. In Figure 11-12, a comparison of the
difference in the H1H modeled concentrations (not paired in space or time) for source PI represents a
20% decrease in the scenarios using the ZORAD roughness option for which land cover was
supplemented with both impervious and canopy data (2001-LC-IMP-CAN-ZORAD) compared with
supplementing land cover with canopy data only (2001-LC-CAN-ZORAD). For the same two
scenarios, there is 44% increase in the concentration for the P3 source. PI is the lowest level point
source which has a 10-meter release height. P3 is also a point source with a release height of 55 meters.
For each of the sites, the greatest differences estimated concentrations occur for the low-level point
source, PI. (Refer to Table 11-5 for the source characteristics of each of the modeled emission
sources.) In keeping with the comparison of roughness values, there are generally smaller differences
in H1H and H2H estimated concentrations, not paired in time or space) when comparing the scenario
that includes both impervious and canopy data to the scenario that uses only land cover data. The
scatter plots, however, do illustrate greater differences in the estimated concentrations across the
different scenarios when paired in space which highlights the sensitivity of AERMOD to roughness.
A comparison of the base case, which uses the 2001 NLCD (2011 Edition), to the scenarios that
use the 1992 NLCD at BTR (Figure 11-27 and Figure 11-28), where there has been little change over
the years in the vicinity of the met tower, shows very little difference in the derived roughness lengths
11-20
-------
(< 0.04 meters) for all seasons and sectors, suggesting that the default base scenario which incorporates
2001 land cover, impervious, and canopy data is comparable to using the 1992 NLCD land cover data
only.
To summarize:
• Supplementing the 2001 land cover data with impervious and canopy data appears to
yield comparable results to the 1992 land cover when there has been little change in land
use overall.
• Supplementing the 2001 land cover data with impervious and canopy data appears to be
more comparable to using land cover data only than supplementing with only
impervious or canopy data.
• A comparison of estimated AERMOD concentrations, paired in space, highlights the
sensitivity of low-level sources to even small changes roughness length.
11-21
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£
1,0.40
ATL - Surface Roughness Length - Winter
Sector 1(90-145)*
Sector 2 (145 - 270)'
Sector 3 (270 - 90)
ATL - Surface Roughness Length - Spring
E,
t040
Sector 1(90-145)*
Sector 2 (145 - 270)*
Sector 3 (270 - 90)
AERSURFACE Scenario
AERSURFACE Scenario
—. °-50
E.
0.40
c
ai
% 0.30
ATL - Surface Roughness Length - Summer
-Sector 1(90-145)*
-Sector 2 (145 - 270)*
-Sector 3 (270 - 90)
ATL - Surface Roughness Length - Autumn
-Sector 1 (90 -145)*
-Sector 2 (145-270)*
-Sector 3 (270 - 90)
•& 0.20
t
w 0.00
if
J3
./
J1
AERSURFACE Scenario
^Processed as Non-airport Sector
g o.io
•t
^ 0.00
jjS'
if
J3
AERSURFACE Scenario
Figure 11-11. ATL Surface Roughness Length by Season, Sector, and AERSURFACE Scenario
11-22
-------
Figure 11-12. ATL H1H Predicted Concentrations by AERSURFACE Scenario and
Emission Source
11-23
-------
Figure 11-13. ATL H2H Predicted Concentrations by AERSURFACE Scenario and
Emission Source
11-24
-------
Figure 11-14. ATL, Scatter Plots, H III and H2H at each Receptor,
2001 Base Case, LC-IMP-CAN-ZORAD Vs. 2001 LC-IMP-CAN-ZOEFF
LC-IMP-CAN_ZORAD (ug:m3)
11-25
-------
ATL
Base: LC-IMP-CAN ZORAD
Case: LC-IMP_ZORAD
Figure 11-15. ATL, Scatter Plots, H1H and H2H at each Receptor,
2001 Base Case, LC-IMP-CAN-ZORAD Vs. 2001 LC-IMP-ZORAD
LC-!MP-CAN_ZORAO (ug.'mS)
11-2
-------
ATL
Base: LC-IMP-CAN ZORAD
Case: LC-IMP-ZOEFF
Figure 11-16. ATL, Scatter Plots, H1H and H2H at each Receptor,
2001 Base Case, LC-IMP-CAN-ZORAD Vs. 2001 LC-IMP-ZOEFF
11-3
-------
ATL
Base: LC-IMP-CAN ZORAD
Case: LC-CAN-ZORAD
1-Hr H1H Scatter Plot
Area
LC-IMP-CAN_ZORAD (ug,'m3)
1-Hr H2H Scatter Plot
Area
LC-IM P-CAW_ZORAD (ug,'m3)
LC-IMP-CAN_ZORAD (ug.'m3)
LC-IMP-CAN_ZORAD (ug.'m3)
LC-IMP-CANZORAD (ug.'m3)
LC-!MP-CAN_ZORAD (ug.'m3)
LC-I MP-C AN_ZORAD (ug.'m3)
LC-IMP-CANZORAD (ug.'mJ)
Distance (km) H
LC-IMP-CAN_ZORAD (ug,'m3)
Distance (Km)
LC-IMP-CAiN_ZORAD (ug/m3)
Distance (km)
LC-I M P-C AN_ZORAD (ug>m3)
Distance (km)
LC-IMP-CAN_ZORAD (ug'mS)
LC-IMP-CAN_ZORAD (ug/m3)
Distance (km)
LC-IMP-CAN_ZORAD (ug/m3)
Distance (km)
Figure 11-17. ATL, Scatter Plots, H1H and H2H at each Receptor,
2001 Base Case, LC-IMP-CAN-ZORAD Vs. 2001 LC-CAN-ZORAD
11-4
-------
ATL
Base: LC-IMP-CAN ZORAD
Ca&e: LC-CAN-ZOEFF
1-Hr H1H Scatter Plot
Area
./V
LC-IMP-CAN_ZORAD (ug,'m3)
1-Hr H2H Scatter Plot
Area
.*» •
Xf'/
J
,t*/
.*?/
LC-IMP-CANZORAD (ug.'mJ)
Distance (km) H
/
/*
\ .
LC-IM P-CAW_ZORAD (ug,'m3)
LC-1MP-CAN_Z0RAD (ug.'m3)
LC-IMP-CAN_ZORAD (ug.'m3)
LC-IMP-CANJ_ZORAD (ug.'m3)
LC-!MP-CAN_ZORAD (ug.'m3)
LC-I MP-C AN_ZORAD (ug.'m3)
/
LC-IMP-CAN_ZORAD (ug,'m3)
Distance (Km)
LC-IMP-CAiN_ZORAD (ug/m3)
Distance (km)
LC-IMP-CAN_ZORAD (ug>m3)
Distance (km)
LC-IMP-CAN_ZORAD (ugfmS)
(km)
LC-IMP-CAN_ZORAD (ugj'm3)
Distance (km)
LC-IMP-CAN_ZORAD (ug.'m3)
Distance (km)
Figure 11-18. ATL, Scatter Plots, H1H and II2H at each Receptor,
2001 Base Case, LC-IMP-CAN-ZORAD Vs. 2001 LC-CAN-ZOEFF
11-5
-------
ATL
Base: LC-IMP-CAN ZORAD
Case: LC-ZORAD
Figure 11-19. ATL, Scatter Plots, IIIII and 112H at each Receptor,
2001 Base Case, LC-IMP-CAN-ZORAD Vs. 2001 LC-ZORAD
LC-IMP-CAN_ZORAD (ug.'m3)
11-6
-------
ATL
Base: LC-IMP-CAN ZORAD
Case: LC-ZOEFF
Figure 11-20. ATL, Scatter Plots, H1H and H2H at each Receptor,
2001 Base Case, LC-IMP-CAN-ZORAD Vs. 2001 LC-ZOEFF
11-7
-------
Figure 11-21. ATL, Scatter Plots, IIIII and II2II at each Receptor,
2001 LC-IMP-ZORAD Vs. 2001 LC-IMP-ZOEFF
LC-IMP-ZORAD (ug;'m3)
LC-IMP-ZORAD (ug.'m3)
11-8
-------
Figure 11-22. ATL, Scatter Plots, Hill and 11211 at each
Receptor, 2001 LC-CAN-ZORAD Vs. 2001 LC-CAN-ZOEFF
LC-CAN-ZORAD (ugi'm3)
LC-CAN-ZORAD {jg'm3)
LC-CAN-ZORAD (ugfm3)
LC-CAN-ZORAD
11-9
-------
ATL
ZORAD Case: LC-ZORAD
ZOEFF Case: LC-ZOEFF
Figure 11-23. ATL, Scatter Plots, H1H and H2H at each Receptor,
2001 LC-ZORAD Vs. 2001 LC-ZOEFF
11-10
-------
BTR - Surface Roughness Length - Winter
£
JZ
w i
-Sector 1(50-210)
-Sector 2 {210 - 280)
-Sector 3 (280 - 50)*
¦f
_ 0.20
.c
j? 0.15
•
0)
M 0.10
*e
4/1 0.00
J*
-------
Figure 11-25. BTR H1H Predicted Concentrations by AERSURFACE Scenario and
Emission Source
11-12
-------
BTR 1-Hour H2H Predicted Concentrations
2400
AERSURFACE Scenario
Figure 11-26. BTR H2H Predicted Concentrations by AERSURFACE Scenario and
Emission Source
11-13
-------
BTR
Base: LC-IMP-CAN-ZORAD
Case: LC-ZORAD_1992
1-Hr H1H Scatter Plot
/
LC-IMP-CAN-ZORAD (ug,'m3)
1-Hr H2H Scatter Plot
/
/
LC-IMP-CAN-ZORAD (ug.'m3)
Distance (km) H
LC-IMP-CAN-ZORAD (ug.'m3>
LC-IMP-CAN-ZORAD (ug'm3)
Distance (Km)
LC-IMP-CAN-ZORAD (ug,'m3)
LC-IMP-CAN-ZORAD (ug'm3>
LC-IMP-CAN-ZORAD (ug/m3j
LC-IMP-CAN-ZORAD (ug.'m3)
4
c-i
LC-IMP-CAN-ZORAD (ug«n3)
LC-IMP-CAN-ZORAD (Ug.'m3)
LC-IMP-CAN-ZORAD (ug.'m3)
LC-IP.1P-CAN-ZORAD (ug/mol
Distance (km)
LC-IMP-CAN-ZORAD (ug.'m3)
LC-IMP-CAN-ZORAD (ug.'m3j
Distance (km)
Figure 11-27. BTR, Scatter Plots, H1H and H2H at each
Receptor, 2001 Base Case, LC-IMP-CAN-ZORAD Vs. 1992 LC-
ZORAD
11-14
-------
BTR
Base: LC-IMP-CAN-ZORAD
Case: LC-20EFF_1992
1-Hr H1H Scatter Plot
Area
LC-IMP-CAN-ZORAD (ug;m3)
LC-IMP-CAN-ZORAD (ug.'m3)
LC-IMP-CAN-ZORAD Iug;m3)
LC-IMP-CAN-ZORAD (ug'm3)
• 7n
•v#
LC-IMP-CAN-ZORAD (ug/m3)
LC-IMP-CAN-ZORAD (og,'m3)
LC-IMP-CAN-ZORAD (ug«n3)
1-Hr H2H Scatter Pi
V
/
LC-IMP-CAN-ZORAD (ug(m3)
Distance (km)
LC-IMP-CAN-ZORAO (ug.'m3)
(km)
/
/
LC-IMP-CAN-ZORAD (ug/m3)
Distance (km)
.N-ZORAD (ug'rn3)
Jr
JF
LC-IMP-CAN-ZORAD (ug.'m3)
Distance (km)
Figure 11-28. BTR, Scatter Plots, 111 II and H2H at each Receptor,
2001 Base Case, LC-IMP-CAN-ZORAD Vs. 1992 LC-ZOEFF
11-15
-------
BTR
ZORAD Case: LC-IMP-CAN-ZORAD
ZOEFF Case: LC-IMP-CAN-ZOEFF
Figure 11-29. BTR, Scatter Plots, H1H and H2H at each Receptor,
2001 Base Case, LC-IMP-CAN-ZORAD Vs. 2001 LC-IMP-CAN-ZOEFF
LC-IMP-CAN-ZORAD
11-16
-------
BTR
Base: LC-IMP-CAN-ZORAD
Case: LC-IMP-ZORAD
Figure 11-30. BTR, Scatter Plots, HIH and H2H at each Receptor,
2001 Base Case, LC-IMP-CAN-ZORAD Vs. 2001 LC-IMP-ZORAD
11-17
-------
BTR
Base: LC-IMP-CAN-ZORAD
Case: LC-IMP-ZOEFF
1-Hr H1H Scatter Plot
Area
if
/
:¦/
LC-IMP-CAN-ZORAD (ugfm3)
1-Hr H2H Scatter Plot
LC-IMP-CAN-ZORAD {ugfm3>
/
LC-IMP-CAN-ZORAD
-------
BTR
Base: LC-IMP-CAN-ZORAD
Case: LC-CAN-ZORAD
1-Hr H1H Scatter Plot
Area
/
LC-IMP-CAN-ZORAD (ugftn3)
1-Hr H2H Scatter Plot
LC-IMP-CAN-ZORAD (ug.'m3)
/
/
/'
4 •.
LC-IMP-CAN-ZORAD {ugfm3>
/
/
IP-CAN-ZORAD (ug.'mS)
LC-IMP-CAN-ZORAD
-------
BTR
Base: LC-IMP-CAN-ZORAD
Case: LC-CAN-ZOEFF
1-Hr H1H Scatter Plot
Area
/
LC-IMP-CAN-ZORAD (ugftn3)
1-Hr H2H Scatter Plot
/
LC-IMP-CAN-ZORAD {ugfm3>
LC-IMP-CAN-ZORAD
-------
BTR
Base: LC-IMP-CAN-ZORAD
Case: LC-ZORAD
1-Hr H1H Scatter Plot
Area
&
/
LC-IMP-CAN-ZORAD (ugftn3)
1-Hr H2H Scatter Plot
LC-IMP-CAN-ZORAD {ugfm3>
LC-IMP-CAN-ZORAD
-------
f
/
/
m
/
60-
1
.rdr
1
1-
/
/
/
/
/'
/
,
¦/
¥
"
/
f
1 "¦
/
LC-IMP-CAN-ZORAD {ugfm3>
LC-IMP-CAN-ZORAD
-------
Figure 11-36. BTR, Scatter Plots, H1H and H2H at each
Receptor, 1992 LC-ZORAD Vs. 1992 LC-ZOEFF
LC-ZORAD (og.'m3)
11-23
-------
ZORAD Case: LC-IMP-ZORAD
ZOEFF Case: LC-IMP-ZOEFF
Figure 11-37. BTR, Q-Q Plots, HI H and H2H at each Receptor,
2001 LC-IMP-ZORAD Vs. 2001 LC-IMP-ZOEFF
LC-IMP-ZORAD (ug/m3)
11-24
-------
BTR
ZORAD Case: LC-CAN-ZORAD
ZOEFF Case: LC-CAN-ZOEFF
Figure 11-38. BTR, Scatter Plots, H1H and H2H at each
Receptor, 2001 LC-CAN-ZORAD Vs. 2001 LC-CAN-ZOEFF
11-25
-------
Figure 11-39. BTR, Scatter Plots, H1H and H2H at each
Receptor, 2001 LC-ZORAD Vs. 2001 LC-ZOEFF
LC-ZORAD (og.'m3)
11-26
-------
RDU - Surface Roughness Length - Winter
£
— 0.25
f
® 0.20
3
0.15
sz
ma
I 010
0)
•g 0.05
3
0.00
0.00
Sector 1(30-60)*
Sector 2 (60 -225)
Sector 3 (225 - 30)*
J
.J
J?
4f
&
¦f
AERSURFACEScenario
>?
-—* 0.25
f
3 0.20
o 0.10
•t 0.05
if
..cf
•/
AERSURFACEScenario
*Processed as Non-airport Sector
Figure 11-40. RDU Surface Roughness Length by Season, Sector, and AERSURFACE Scenario
11-27
-------
Figure 11-41. RDU H1H Predicted Concentrations by AERSURFACE Scenario and
Emission Source
11-28
-------
Figure 11-42. RDU H2H Predicted Concentrations by AERSURFACE Scenario and
Emission Source
11-29
-------
RDU
ZORAD Case: LC-IMP-CAN-ZORAD
ZOEFF Case: LC-IMP-CAN-ZOEFF
Figure 11-43. RDU, Scatter Plots, H1H and H2H at each Receptor,
2001 Base Case, LC-IMP-CAN-ZORAD Vs. 2001 LC-IMP-CAN-ZOEFF
LC-IMP-CAN-ZORAD fug.'m3)
•ZORAD (ug.'m3)
11-30
-------
RDU
Base: LC-IMP-CAN_ZORAD
Case: LCHMP-ZORAD
Figure 11-44. RDU, Scatter Plots, H1H and H2H at each Receptor,
2001 Base Case, LC-IMP-CAN-ZORAD Vs. 2001 LC-IMP-ZORAD
LC-IMP-CAN_ZORAD (ug/m3)
LC-IMP-CAM_ZORAD (ug.'m3)
11-31
-------
RDU
Base: LC-IMP-CAN_ZORAD
Case: LC-IMP-ZOEFF
Figure 11-45. RDU, Scatter Plots, H1H and II2II at each Receptor,
2001 Base Case, LC-IMP-CAN-ZORAD Vs. 2001 LC-IMP-ZOEFF
LC-I MP-CAN_2ORA0
-------
RDU
Base: LC-IMP-CAN_ZORAD
Case: LC-CAN-ZORAD
1-Hr H1H Scatter Plot
Area
if
/
LC-IMP-CAN_ZORAD (ug.'m3)
1-Hr H2H Scatter Plot
LC-IMP-CAN_ZORAD (ugfm3)
LC-IMP-CAN_ZORAO (ug/m3)
LC-IMP-CAN_ZORAD (ug;rn3)
LC-IMP-CAN_ZORAD (ug.'mS)
LC-IMP-CAN_ZORAD (ug/m3)
LC-I MP-CAN_ZORAD (ug/m3)
/
LC-IMP-CAN_ZORAD (ug.'m3)
Distance (Km)
"¦/
LC-IMP-CAN_ZORAD (ugfm3)
Distance (km)
\l_ZORAD (ug'm3)
C-IMP-CAN_ZORAD (ug'mS)
LC-IMP-CAN_ZORAD (ug.'m3)
Distance (km)
Figure 11-46. RDU, Scatter Plots, H1H and H2H at each Receptor,
2001 Base Case, LC-IMP-CAN-ZORAD Vs. 2001 LC-CAN-ZORAD
11-33
-------
RDU
Base: LC-IMP-CAN_ZORAD
Case: LC-CAN-ZOEFF
1-Hr H1H Scatter Plot
Area
f
/
LC-IMP-CAN_ZORAD (ug.'m3)
1-Hr H2H Scatter Plot
/
/
«/ .
LC-IMP-CAN_ZORAD (ugfm3)
LC-IMP-CAN_ZORAO (ug/m3)
LC-IMP-CAN_ZORAD (ug.'m3)
LC-IMP-CAN_ZORAD (ug.'mS)
LC-IMP-CAN_ZORAD (ug/m3)
LC-I MP-CAN_ZORAD (ug/m3)
LC-IMP-CAN_ZORAD (ug:m3)
Distance (Km)
,-r
Av
LC-IMP-CAN_ZORAD (ugrtrtf)
Distance (km)
\l_ZORAD (ug'm3)
C-IMP-CAN_ZORAD (ug'mS)
N_ZORAD (ug,'m3)
LC-IMP-CAN_ZORAD (ug.'m3)
Distance (krnl
Figure 11-47. RDU, Scatter Plots, H1H and H2H at each Receptor,
2001 Base Case, LC-IMP-CAN-ZORAD Vs. 2001 LC-CAN-ZOEFF
11-34
-------
Figure 11-48. RDU, Scatter Plots, H1H and H2H at each
Receptor, 2001 Base Case, LC-IMP-CAN-ZORAD Vs. 2001 LC-
ZORAD
LC-IMP-CAN_ZORAD (ug.'mS)
11-35
-------
Figure 11-49. RDU, Scatter Plots, H1H and H2H at each
Receptor, 2001 Base Case, LC-IMP-CAN-ZORAD Vs. 2001 LC-
ZOEFF
-IMP-CAN_ZORAD !ug.'rn3)
11-36
-------
RDU
20RAD Case: LC-IMP-ZORAD
ZOEFF Case: LC-IMP-ZOEFF
Figure 11-50. RDU, Scatter Plots, H1H and H2H at each
Receptor, 2001 LC-IMP-ZORAD Vs. 2001 LC-IMP-ZOEFF
LC-IMP-ZORAD (ug.'m3)
I 1-37
-------
RDU
ZORAD Case: LC-CAN-ZORAD
ZOEFF Case: LC-CAN-ZOEFF
Figure 11-51. RDU, Scatter Plots, H1H and H2H at each
Receptor, 2001 LC-CAN-ZORAD Vs. 2001 LC-CAN-ZOEFF
11-38
-------
RDU
ZORAD Case: LC-ZORAD
ZOEFF Case: LC-ZOEFF
Figure 11-52. RDU, Scatter Plots, H1H and H2H at each
Receptor, 2001 LC-ZORAD Vs. 2001 LC-ZOEFF
LC-ZORAD (ug.'m3)
11-39
-------
11.4 Comparison of Surface Roughness Length Estimated with 2001 NLCD (2011 Edition) and
2016 NLCD
This updated inter-comparison using AERSURFACE version 20060 is expanded to include a
comparison of the estimated surface roughness length for ATL, BTR, and RDU, based on the 2001
NLCD (2011 edition) and presented in the sections above, to the estimated surface roughness length
based on the 2016 NLCD. Figure 11-53, Figure 11-56, and Figure 11-59 compare the landcover,
percent impervious, and percent tree canopy for ATL, BTR, and RDU, respectively for the 2001 NLCD
(2011 edition) to the 2016 NLCD. Figure 11-54 and Figure 11-55 compare seasonal surface roughness
lengths for ATL estimated with the 2001 NLCD (2011 edition) and the 2016 NLCD. Similarly, Figure
11-57 and Figure 11-58 compare seasonal surface roughness lengths for BTR, and Figure 11-60 and
Figure 11-61 compare seasonal roughness lengths estimated for RDU. In general, each of the three
sites have experienced and increase in area characterized as "Developed" with an increase in the
amount of impervious area and a decrease in tree canopy.
11-40
-------
2001 NLCD
2016 NLCD
-fa MeteorologicalTower
HI 10 x 10 km Area
0 1 km Radius with Sectors
¦ 11 Open Water
[ 112 Perennial Ice/ Snow
' 21 Developed. Open Space
] 22 Developed, Low Intensity
^|23 Developed. Medium Intensity
¦¦24 Developed. High Intensity
^|31 Barren Land (Rock/Sand/Clay)
H 41 Deciduous Forest
42 Evergreen Forest
43 Mixed Forest
^|51 Dwarf Scrub*
1 152 Shrub/Scrub
I 171 Grassland/Herbaceous
I 172 Sedge/Herbaceous*
lit 173 Lichens*
m 74 Moss*
I 181 Pasture/Hay
¦ 82 Cultivated Crops
90 Woody Wetlands
95 Emergent Herbaceous Wetlands
* Alaska only
f :«t, j'*> » •
Ipipc
50%
100%
Figure 11-53. Comparison of 2001 NLCD (2011 Edition) to 2016 NLCD for ATL
Land Cover (top), Percent Impervious (middle), and Percent Tree Canopy (bottom)
11-41
-------
2001 NLCD
2016 NLCD
_ 0.S0
£
¦£ 0.40
e
v
a ojo
0.20
ATI - Surface Roughness Length - Winter
ATL - Surface Roughness Length - Winter
-Sector 1 (90- 14S)'
-Sector 2 (145 • 27CT
-Sector 3 (220 • 90)
f W
AERSURFACE Scenario
E.
toaa
-Sector 1(90- 145)*
-Sector 2 (145-270J*
-Sector 3 (270-90)
AERSURFACE Swnario
£
£ 0.40
c
*
g OJO
fr-
ee
2 o.io
ATL - Surface Roughness Length - Spring
-^•Sector 1(90-US)*
Sector 2 (US • 270)'
—~—Sector 3 (270 - SO)
•
J
4
¦f -f r
AERSURFACE Scenario
£
|,0.40
ATL - Surface Roughness Length - Spring
Sector 1(90-145)*
Sector 2 (145-270)'
Sector 3 (270 • 90)
#
-------
2001 NLCD
2016 NLCD
ATL - Surface Roughness Length - Summer
ATL ¦ Surface Roughness Length ¦ Summer
_E
§0.40
Sector 1 (90- t4S)B
Sector ?, (145 - 270} *
Sector 3 (270 - 90)
AERSURFACE Scenario
^ 0.40
Sector 1 (90* 14S)*
Sector 2 (14S • 270}*
Sector 3 (270 • 90)
AERSURFACE Scenario
ATL - Surface Roughness Length - Autumn
ATL - Surface Roughness Length • Autumn
Sector 1 (90- 145)*
¦Sector 2 1145 270)'
Sector 3 T2TO-9Ch)
AERSURFACE Scenario
Sector 1 (90- 145)'
Sector 2 (145 - 2701*
Sector 3 (270 • 90)
AERSURFACE Scenario
Figure 11-55. Surface Roughness Length Estimated for ATL using 2001 NLCD (2011 Edition) and 2016 NLCD
Summer Months (top), Autumn Months (bottom)
11-43
-------
MeteorologicalTower
l~l 10 x 10 km Area
(0 1 km Radius with Sectors
H11 Open Water
I ] 12 Perennial Ice/ Snow
21 Developed. Open Space
122 Developed. Low Intensity
H 23 Developed. Medium Intensity
24 Developed, High Intensity
H31 Barren Land {Rock/Sand/Clay)
HH 41 Deciduous Forest
^¦42 Evergreen Forest
en 43 Mixed Forest
^^51 Dwarf Scrub*
52 Shrub/Scrub
I 171 Grassland/Herbaceous
I 172 Sedge/Herbaceous*
II 173 Lichens*
M 74 Moss*
]81 Pasture/Hay
H 82 Cultivated Crops
90 Woody Wetlands
195 Emergent Herbaceous Wetlands
* Alaska only
2001 NLCD
-r •. v*: - f-
!a mw
st-V —-_yy I
2016 NLCD
, * I
• l: > -£»* ¦* i
l 'X " *"v' ftl —• » *¦
i p. Vftpi ''' •'flr, '-i..' t
J«a5\is
50%
100%
Figure 11-56. Comparison of 2001 NLCD (2011 Edition) to 2016 NLCD for BTR
Land Cover (top), Percent Impervious (middle), and Percent Tree Canopy (bottom)
11-44
-------
&
% 0.15
2001 NLCD
BTR - Surface Roughness Length - Winter
—Sector 1 <50- 210)
-Sector 2 <210 ?fl0|
—Sector 3 <280 • SO)*
AERSURFACE Scenario
2016 NLCD
BTR - Surface Roughness Length - Winter
-Sector 1 <50 210)
—Sector i (210
-Sector 3<230-SO)*
&
jr
-f ¦&
f /
W #
./ J ,sf
? y ./ ~ ./
AERSURFACE Scenario
Figure 11-57. Surface Roughness Length Estimated for BTR using 2001 NLCD (2011 Edition) and 2016 NLCD
Winter Months (top), Spring Months (bottom)
11-45
-------
2001 NLCD
2016 NLCD
Figure 11-58. Surface Roughness Length Estimated for BTR using 2001 NLCD (2011 Edition) and 2016 NLCD
Summer Months (top), Autumn Months (bottom)
11-46
-------
2001 NLCD
2016 NLCD
MeteorologicalTower
l~l 10 x 10 km Area
0 1 km Radius with Sectors
H11 Open Water
112 Perennial Ice/ Snow
j 21 Developed. Open Space
122 Developed, Low Intensity
H 23 Developed. Medium Intensity
¦ 24 Developed, High Intensity
1 131 Barren Land (Rock/Sand/Clay)
1—1| 41 Deciduous Forest
42 Evergreen Forest
] 43 Mixed Forest
^¦51 Dwarf Scrub*
,52 Shrub/Scrub
171 Grassland/Herbaceous
I 1172 Sedge/Herbaceous*
BH 73 Lichens*
li i 74 Moss'
81 Pasture/Hay
82 Cultivated Crops
~ 90 Woody Wetlands
HI 95 Emergent Herbaceous Wetlands
* Alaska only
100%
Figure 11-59. Comparison of 2001 NLCD (2011 Edition) to 2016 NLCD for RDU BTR
Land Cover (top), Percent Impervious (middle), and Percent Tree Canopy (bottom)
11-47
-------
2001 NLCD
2016 NLCD
RDU - Surface Roughness Length - Spring RDU - Surfate Roughness Length - Spring
AE RSURFACE Scenario AERSURFACE Scenario
Figure 11-60. Surface Roughness Length Estimated for RDU using 2001 NLCD (2011 Edition) and 2016 NLCD
Winter Months (top), Spring Months (bottom)
11-48
-------
2001 NLCD
RDU - Surface Roughness Length * Summer
2 0.20
s«,»
J O.IO
SaOW-lOO-IHt*
Sector 2 (60 • 22S)
Sector Jfi2S • *))•
^ ^
f / jf J J?
.r
*
¦f
AE R5URFACE Sc«n»rto
2016 NLCD
RDU - Surface Roughness Length - Summer
^ o.is
f
5 o.io
-s*tu>j a (30- tor
-Sector 2 (60- 22S)
-Sector i 1225 *>)•
s j* j
&
, -p
ty
AERSURFACE Scenario
RDU - Surface Roughness Length - Autumn RDU - Surface Roughness Length - Autumn
AERSURFACE Scenario AERSURFACE Scenario
Figure 11-61. Surface Roughness Length Estimated for RDU using 2001 NLCD (2011 Edition) and 2016 NLCD
Summer Months (top), Autumn Months (bottom)
11-49
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12,0 Appendix H: Error and Warning Messages
El00 Invalid Pathway Specified
El05 Invalid Keyword Specified
E110 Keyword is Not Valid for This Pathway
E115 STARTING or FINISHED Out of Sequence
El20 Pathway is Out of Sequence
El25 Missing FINISHED-Runstream File Incomplete
E13 0 Missing Mandatory Keyword
El35 Nonrepeatable Keyword
El40 Keyword is Out of Sequence
E150 Too Few Parameters Specified for Keyword
El55 Too Many Parameters Specified for Keyword
El60 Invalid Parameter Specified for Keyword
El70 Keyword Conflict Encountered
E200 Only one of PRIMARY or SECONDARY allowed
E201 Only one of ZOEFF or ZORAD allowed
E202 Anem. height is required when ZOEFF option is used
203 A LC Data File Has Not Been Specified
E205 Invalid Keyword for Number of Sectors Specified
E206 NAD Grid Files Missing (*.los & *.las)
E208 Invalid # SECTOR Definitions for # of Sectors
W209 DBGOPT EFFRAD is not applicable with OPTIONS ZORAD
E210 SEASON Keyword Only Valid with ANNUAL and MONTHLY
W227 Calc. IBL Height < Minimum (Based on Anem. Ht.)
W228 Calc. IBL Height > Maximum (Based on Anem. Ht.)
12-1
-------
E230 Primary Title Cannot Be Blank
W235 Secondary Title is Blank
E240 File Name is Too Long, Exceeds Maximum Length
E245 Illegal Numerical Field Encountered
E247 Anemometer Height Must Be Within the Valid Range:
E248 IBL Factor Must Be Within the Valid Range:
E250 Invalid Horizontal Datum Specified
E255 Arid Climate is Invalid with Continuous Snow
E260 Invalid Number of Sectors Specified
E265 Invalid Sector ID Specified
E266 Sector IDs Must Be Consecutive
E267 Gap or Overlap in Sector Start/End Directions
E268 Min Sector Width of 30-degrees Required
E269 Coverage For All Sectors Must Equal 360-degrees
E270 Numeric Value Out of Range
E271 Min Sector Width of 22.5-degrees Required
E275 WINTERWS Not Valid When CLIMATE = NOSNOW
E280 Invalid Month Specified
E285 Month Was Previously Assigned to a Season
E290 File does not exist
W294 Recommended use of Impervious and Canopy data
E295 Both Impervious and Canopy input files required
E296 Must use same year for NLCD, MPRV, and CNPY
W297 Not a valid NLCD year
W305 EFFRAD Not Specified on CO DEBUGOPT; Ignored
W310 GRID Not Specified on CO DEBUGOPT; Ignored
12-2
-------
W315 TIFF Not Specified on CO DEBUGOPT; Ignored
E340 File Name is Too Long, Exceeds Maximum Length
E405 Byte Order of Processor Could Not Be Determined
E410 Byte Order of GeoTIFF Undetermined (See Log File)
E415 File is Not Correctly Identified as a TIFF File
E420 Allocation Error While Reading GeoTIFF File
W425 GeoTIFF File Does Not Contain Georeference Info
W430 GeoTIFF File Contains Unidentified Data Type
W435 Required Georeference Data Was Not Found in GeoTIFF
W440 Multiple Values Found for a GeoKey. Expecting One
E500 Fatal Error Occurred Opening a Primary I/O File
E505 Fatal Error Occurred Reading from Input File
E510 Fatal Error Occurred Reading from Temporary File
E515 Fatal Error Occurred Writing to Output File
E600 The Study Area Extends Beyond the Data File
12-3
-------
13,0 References
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www.alternatiff.com/resources/TIFF6.pdf
Cimorelli, A. J., S. G. Perry, A. Venkatram, J. C. Weil, R. J. Paine, R. B. Wilson, R. F. Lee, W. D.
Peters, R. W. Brode, and J. O. Paumier, 2004. AERMOD: Description of Model Formulation,
EPA-454/R-03-004. U.S. Environmental Protection Agency, Research Triangle Park, NC.
EPA, 2024a: User's Guide for the AERMOD Meteorological Preprocessor (AERMET). EPA-454/B-24-
004. U.S. Environmental Protection Agency, Research Triangle Park, NC
EPA, 2024b: User's Guide for the AMS/EPA Regulatory Model - AERMOD. EPA-454/B-24-007. U.S.
Environmental Protection Agency, Research Triangle Park, NC.
EPA, 2024c: AERMOD Implementation Guide (Revised October 2024). EPA-454/B-24-009. U.S.
Environmental Protection Agency, Research Triangle Park, North Carolina 27711.
EPA, 2019a: User's Guide for Draft AERSURFACE Tool (Version 19039 DRFT). EPA-454/B-19-001,
February 2019. U.S. Environmental Protection Agency, Research Triangle Park, North Carolina
27711.
EPA, 2019b: User's Manual: The Mesoscale Model Interface Program (MMIF). Prepared for US EPA
by Ramboll. Version 3.4.1.
Garratt, J. R., 1990: The Internal Boundary Layer - A Review. Boundary-Layer Meteorology. 50: 171-
203.
Garratt, J. R., 1992: The Atmospheric Boundary Layer. Cambridge University Press, New York, New
York, 334pp.
Miyake, M., 1965: Transformation of the Atmospheric Boundary Layer over Inhomogeneous Surfaces,
Department of Atmospheric Sciences, Univ. of Washington, Scientific Report. Office of Naval
Research, Contract 477 (24) (NR 307-252). October, 1965.
Oke, T. R., 1978: Boundary Layer Climates. John Wiley and Sons, New York, New York, 372pp.
Randerson, D., 1984, "Atmospheric Boundary Layer," in Atmospheric Science and Power Production,
ed., D. Randerson. Technical Information Center, Office of Science and Technical Information,
U.S. Department of Energy, Springfield, VA, 850pp.
Slade, D.H. (ed.), 1968. Meteorology and Atomic Energy. Division of Technical Information, U.S.
13-4
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Atomic Energy Commission. Oak Ridge, TN, 445pp.
Stull, R. B., 1988. An Introduction to Boundary Layer Meteorology. Kluwer Academic Publishers, The
Netherlands, 666pp.
Ritter, N. and M. Ruth, 1995: GeoTIFF Format Specification.
www.remotesensing.org/geotiff/spec/geotiffhome.html.
Wieringa, J., 1976: An objective exposure correction method for average wind speeds measured at a
sheltered location. Quarterly Journal of the Royal Meteorological Society. 102 (431): 241-253,
doi:10.1002/qj.49710243119.
Wieringa, J., 1993: Representative roughness parameters for homogeneous terrain. Boundary Layer
Meteorology. 63: 323-363.
13-5
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United States Office of Air Quality Planning and Standards Publication No. EPA-454/B-24-003
Environmental Protection Air Quality Assessment Division November 2024
Agency Research Triangle Park, NC
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