United States
Environmental Protection
Agency
Air and Energy
Engineering Research Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/S7-88/024 Mar. 1989
x°/EPA Project Summary
Documentation of Spatial
Allocation Factor
Procedures for the 1980
NAPAP Emissions Inventory
Theresa A. Beaulieu and Lysa G. Modica
Spatial allocation factors were
developed to apportion NAPAP area
source emissions from counties to
individual grid cells for input to the
Regional Acid Deposition Model
(RADM) and Regional Oxidant Model
(ROM). The development effort
focused on creating a variety of
spatial surrogates to allow the user
maximum flexibility in assigning area
source emissions to modeling grid
cells. The surrogates are used to
represent the subcounty distribution
of area source emissions for each
category. Fourteen surrogate indi-
cators were developed for use with
the NAPAP inventory based on
housing, population, and land use
data. Fortran programs were devel-
oped to generate the spatial factors.
These programs are available on a
companion magnetic tape. The user
can specify processing options and
grid definition by means of control
options files accessed by the
programs. Once the subcounty
distribution of each surrogate is
determined, area source emissions
categories are matched to the most
appropriate surrogate. The resultant
Spatial Allocation Factor File is input
to the Spatial Allocation Module of
the Flexible Regional Emissions Data
System.
This Project Summary was devel-
oped by EPA's Air and Energy
Engineering Research Laboratory,
Research Triangle Park, NC, to an-
nounce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Background
The National Acid Precipitation
Assessment Program (NAPAP) was
established by Congress in 1980 to
coordinate and expand research on
problems posed by acid deposition in
and around the U.S. The program is
managed through the Interagency Task
Force on Acid Precipitation which
coordinates seven task groups having
specific technical responsibilities. The
Task Group on Emissions and Controls is
charged with developing comprehensive
and accurate inventories of emissions
from sources thought to be important in
acid deposition processes. To fulfill its
objective and support other related
NAPAP research, the Task Group on
Emissions and Controls has generated a
number of major emissions data bases
using 1980 as the base year.
The primary focus of the 1980 NAPAP
Emissions Inventory is the fulfillment of
the emissions data requirements for
developing and testing the Eulerian
Regional Acid Deposition Model (RADM).
In addition, emissions data are also used
to support applications of the Regional
Oxidant Model (ROM). To create
emissions data suitable as model input,
the 1980 Annual Inventory had to be
resolved temporally, spatially, and by
component species; allocation factors
were developed to address these mod-
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eling requirements. In addition, a data
handling system was developed to
create subsequent versions of the
NAPAP Emissions Inventory. The
Flexible Regional Emissions Data
System (FREDS) for the 1980 NAPAP
Emissions Inventory, consisting of five
primary independent modules, was used
to preprocess the 1980 NAPAP
emissions data for input to the RADM.
Spatial allocation factors were
developed to apportion area source
emissions from counties to individual grid
cells, 1/4° longitude by 1/68 latitude
(approximately 20 x 20 km). The goal of
the spatial allocation factor development
effort was to create as many surrogate
values as possible for each county,
allowing the user maximum flexibility in
assigning county-level emissions to
specific grid cells. These surrogates are
used to estimate the subcounty distri-
bution of area source emissions.
Data used to estimate area source
emissions for the NAPAP grid system
are derived from diverse sources. Actual
emissions or data from which emissions
may be calculated (e.g., activity levels
such as tons of coal sold or gasoline fuel
consumption) are reported at the State
and county level. Census data for
population and housing are reported at
various levels of geographic coverage,
including subcounty levels. Land use
data from satellite imagery and land
use/cover maps were developed for a
1/4° longitude by 1/6° latitude grid. The
land use by grid cell, however, required
resolution relative to the county-level.
Fortran programs were developed to
assimilate the population, housing and
land use data into county-level values
and redistribute the information into
spatial fractions (a spatial fraction is the
fraction of a county's population, housing
or land use contained within a specific
grid cell).
Fourteen surrogate indicators were
developed for use with the NAPAP
inventory based on housing, population,
and land use data. The categories and
sources of data are summarized in Table
1. Once the subcounty distribution of
each surrogate indicator is determined,
area source emission categories are
matched to the most appropriate
surrogate indicators. For 1980 NAPAP
application, 6 of the 14 surrogates are
used for spatial allocation. The resultant
Spatial Allocation Factor File (SAFF), is
input to the Spatial Allocation Module
(SAM) of the Flexible Regional Emissions
Data System (FREDS) such that area
source emissions may be spatially
distributed among approximately 20 x 20
km grid cells.
SAM spatially resolves county-lev
area source emissions to grid cells usir
spatial allocation factors and a use
defined grid. The grid boundaries ar
cell size are input as control option
SAM accepts an EBCDIC spatial fact
file - the Spatial Allocation Factor Fi
(SAFF) - output by the Spatial Allocatic
Factor Preprocessor (SAFP), the fin
program executed for the generation
spatial factors. This file contains SC<
state, county, column, row, and a spati
surrogate value assigned to each recor
Spatial allocation is accomplished t
match-merging area source emissior
records to those in the SAFF an
multiplying county-level area sourc
emissions by their corresponding spati
fractions.
Spatial Factor Overview
The development of spatial allocatic
factors is based on two primary da
sources: U.S. Department of Commerc
Bureau of the Census, Census i
Population and Housing (1980), and lar
use/classification data derived fro
1972-1973 Landsat satellite imagei
and land use/cover maps. Separa
software was created to process tr
Census and Landsat data. Dal
processing utilizes the National Comput
Table 1. Spatial Allocation Surrogates Available in the NAPAP
Spatial Allocation Factor File
Surrogate
Indicator
No.
i
2
3
4
5
6
7
a
9
10
11
12
13
14
Surrogate
Indicator
Population
Housing
Urban Land
Agricultural Land
Range/and
Deciduous Forest
Coniferous Forest
Mixed Forest and
Forested Wetland
Water
Outside Study Area
Non-forested Wetland
Mixed Agricultural Land
and Range/and
Composite Forest
Land Area
Source*
1980 Census
1980 Census
Landsat
Landsat
Landsat
Landsat
Landsat
Landsat
Landsat
Landsat
Landsat
Landsat
Landsat
EPA/Alliance
a National Acid Precipitation Assessment Program Emission
Inventory Allocation Factors, EPA/600/7-85/035 (NTIS; PB86-104
247), September 1985.
bLandsat data are for 1971-1973.
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Center's (NCC) Sperry UNIVAC and IBM
"3090.
The input data and Fortran programs,
which are available on a companion
magnetic tape, are summarized below:
• The Bureau of the Census, Census of
Population and Housing, 1980 is used
to develop the census-based spatial
allocation surrogates. This file consists
principally of sample data expanded to
represent the total population. Census
data are summarized at the State level
and are broken down in hierarchical
sequence to more specific geographic
levels such as block groups and
enumeration districts.
• The Landsat and land use/cover data,
in conjunction with county-grid area
relationships are used to derive land
use specific spatial allocation factors.
The land use/cover data base was
developed using Landsat mosaic
images covering the periods July 23 to
October 31, 1972 and January 1 to
March 31, 1973, and Land Use and
Land Cover maps developed in the
middle-to-late 1970's. Land use/
cover percentages for 1/4° longitude
by 1/6° latitude grid cells are reported
for the following categories: urban
land, agricultural land, rangeland, de-
ciduous forest land, coniferous forest
land, mixed agricultural land and
rangeland, mixed forest land, water,
barren land, and non-forested wet-
land.
• The CREATE7A program condenses
and reformats the census files,
substitutes NEDS for FIPS codes, and
calculates sub-county fractions of
housing and population. The program
input includes the state-specific
census of population and housing data,
a control options file, the FIPS to
NEDS conversion file, and the
Massachusetts Update File (used to
process data relative to Air Pollution
Control Districts instead of counties).
This program is executed on the
Sperry UNIVAC.
The CREATE5A program generates
county-to-grid allocation files for
each State output by CREATE7A.
Allocation files may be created for up
to 11 surrogate categories. In addition
to the condensed census file output by
CREATE7A, a user-defined control
options file is input to CREATE5A. This
program is also executed on the
Sperry UNIVAC.
The program VIRGINIA is executed for
the State of Virginia to adjust the
census data for the state's independ-
ent cities. Of the 41 independent cities,
31 are considered by CREATE5A to
be separate from their respective
counties, although both possess the
same NEDS ID. VIRGINIA merges the
data by NEDS code, combining
identical rows and columns, and
adjusting corresponding county totals.
Virginia is executed on Sperry
UNIVAC.
> The NEWLAND program reads and
processes the land use and land cover
data. The main function of the program
is to convert the land use data,
reported as the percent of each grid
occupied by each land use category,
into the fraction of each county's land
use assigned to each grid cell. Two
input files are required to process the
data: land use percentages and
county-to-grid fractions. Two addi-
tional categories are calculated in
NEWLAND: composite forest land and
land area. Newland is also executed on
the Sperry UNIVAC.
• The program SPACEMERGE, executed
on the Sperry, reads spatial fractions
generated from the land use and
census data and match merges each
record by NEDS ID, column number,
and row number. In addition,
SPACEMERGE checks for Massa-
chusetts' records such that land use
fractions, based on county areas, may
be converted to land use fractions by
Air Pollution Control Districts.
• The Spatial Allocation Factor Prepro-
cessor (SAFP) creates spatial alloca-
tion factors which are compatible with
the SAM of FREDS. The main
function of the program is to match
the spatial fractions output by
SPACEMERGE to area source cate-
gories by means of a user-defined
surrogate selection file. Three input
files are accessed by SAFP: the control
file, the surrogate selection file, and the
spatial fractions. In addition, SAFP
performs quality control checks on the
input spatial fractions.
Conclusions
This report documents the software
used to generate spatial allocation factors
used in the development of the resolved
1980 NAPAP emissions inventory. The
Fortran programs contained in the
document and on magnetic tape support
the spatial resolution requirements of
acid deposition and photochemical
oxidant models. The availability of the
spatial factor software documentation and
magnetic tape allow use of this
methodology by all inventory users. In
addition, documentation of the programs
in accordance with EPA's automatic data
processing standards ensures their
usefulness for future applications.
M
•>
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Theresa A. Beaulieu and Lysa G. Modica are with Alliance Technologies
Corporation, Bedford, MA 01730.
J. David Mobley is the EPA Project Officer (see below).
The complete report consists of paper copy and magnetic tape, entitled
"Documentation of Spatial Allocation Factor Procedures for the 1980 NAPAP
Emissions Inventory,"
Paper Copy (Order No. PB 89-159 4791 AS; Cost: $28.95)
Magnetic Tape (Order No. PB 89-159 461/AS; Cost: $325.00, cost of magnetic
tape includes paper copy)
The above items will be available only from: (cost subject to change)
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Air and Energy Engineering Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection
. Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
EPA/600/S7-88/024
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