AERSCREEN User’s Guide
                                               EPA-454/B-21-005
                                                      April 2021




       AERSCREEN User’s Guide




   U.S. Environmental Protection Agency
Office of Air Quality Planning and Standards
      Air Quality Assessment Division
        Air Quality Modeling Group
  Research Triangle Park, North Carolina
                                         Preface

This document provides a description of AERSCREEN, the screening version of AERMOD.
Included in the document are descriptions of inputs, processing methodology in AERSCREEN,
and outputs. This document represents a revision to the previous AERSCREEN User’s Guide,
EPA document number EPA-454/B-16-004.




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                                    Acknowledgements

AERSCREEN and the AERSCREEN User’s guide The AERSURFACE User’s Guide has been
developed by the Air Quality Modeling Group within EPA’s Office of Air Quality Planning and
Standards and AERSCREEN Workgroup, with input from the AERMOD Implementation
Workgroup. The AERSCREEN code was initially developed by James Haywood, Michigan
Department of Environmental Quality.




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                                                                 Contents
Preface............................................................................................................................................. ii
Acknowledgements ........................................................................................................................ iii
Figures............................................................................................................................................ vi
Tables ............................................................................................................................................. ix
1. Overview of AERSCREEN ....................................................................................................... 1
   1.1 Description of AERSCREEN ............................................................................................... 2
       1.1.1 Changes to AERSCREEN .............................................................................................. 3
   1.2 Description of MAKEMET ................................................................................................... 5
   1.3 Differences with SCREEN3 .................................................................................................. 8
2. AERSCREEN features................................................................................................................ 9
   2.1 Source inputs ......................................................................................................................... 9
       2.1.1 Point, capped stacks and horizontal stack sources ....................................................... 10
       2.1.2 Flares ............................................................................................................................ 13
       2.1.3 Volume sources ............................................................................................................ 14
       2.1.4 Rectangular area sources .............................................................................................. 15
       2.1.5 Circular area sources .................................................................................................... 16
       2.1.6 NOx to NO2 conversion ................................................................................................ 17
       2.1.7 Other inputs .................................................................................................................. 18
   2.2 Downwash ........................................................................................................................... 18
   2.3 Meteorology and surface characteristics ............................................................................. 21
   2.4 Terrain ................................................................................................................................. 25
   2.6 Inclusion of discrete distances............................................................................................. 29
   2.7 Other inputs ......................................................................................................................... 31
   2.8 Fumigation options.............................................................................................................. 32
   2.9 Optional debug file .............................................................................................................. 34
   2.10 Non-default name for output file ....................................................................................... 34
   2.11 Error checking ................................................................................................................... 35
3. AERSCREEN Program Execution .......................................................................................... 37
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   3.1 Data input and validation .................................................................................................... 38
   3.2 Meteorological data files ..................................................................................................... 45
   3.3 BPIPPRM execution ........................................................................................................... 46
   3.4 Source elevation calculation................................................................................................ 47
   3.4 Receptor network ................................................................................................................ 47
   3.5 PROBE ................................................................................................................................ 48
   3.6 FLOWSECTOR .................................................................................................................. 49
      3.6.1 Rectangular area sources .............................................................................................. 50
      3.6.2 Non-rectangular area sources ....................................................................................... 53
   3.7 REFINE ............................................................................................................................... 56
   3.8 Fumigation .......................................................................................................................... 57
      3.8.1 Selection of meteorological data .................................................................................. 57
      3.8.2 Inversion break-up fumigation ..................................................................................... 58
      3.8.3 Shoreline fumigation .................................................................................................... 58
      3.8.4 AERSCREEN run option ............................................................................................. 60
   3.9 Outputs ................................................................................................................................ 60
4. Example run ............................................................................................................................. 62
   4.1 Processing and log file ........................................................................................................ 65
   4.2 AERSCREEN output .......................................................................................................... 82
5. References ................................................................................................................................ 95
Appendix A. Input parameters and invalid responses ............................................................... A-1




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                                                                    Figures
Figure 1. User prompts for MAKEMET........................................................................................ 6
Figure 2. AERSCREEN.INP and prompts inputs for point sources. ........................................... 11
Figure 3. AERSCREEN.INP and prompts inputs for capped stack sources. .............................. 12
Figure 4. AERSCREEN.INP and prompts inputs for horizontal stack sources........................... 13
Figure 5. AERSCREEN.INP and prompts inputs for flare sources. ............................................ 14
Figure 6. AERSCREEN.INP and prompts inputs for volume sources. ....................................... 15
Figure 7. AERSCREEN.INP and prompts inputs for rectangular area sources. ......................... 16
Figure 8. AERSCREEN.INP and prompts inputs for circular area sources. ............................... 16
Figure 9. AERSCREEN.INP and prompts inputs for NOx to NO2 conversion. ......................... 18
Figure 10. AERSCREEN.INP and prompts inputs for building inputs. ...................................... 20
Figure 11. Stack and building orientation for a building oriented 90 degrees to north and stack
oriented 45 degrees to north. ......................................................................................................... 21
Figure 12. AERSCREEN.INP and prompts inputs for meteorological and surface characteristics
data. ............................................................................................................................................... 23
Figure 13. AERSCREEN.INP and prompts inputs for terrain data. ............................................ 26
Figure 14. Example formats of demlist.txt. ................................................................................. 29
Figure 15. AERSCREEN.INP and prompts inputs for including discrete distances. .................. 30
Figure 16. Sample distances in a discrete distances text file. ...................................................... 30
Figure 17. AERSCREEN.INP and prompts inputs for other inputs. ........................................... 31
Figure 18. AERSCREEN.inp and prompt inputs for fumigation. ............................................... 33
Figure 19. AERSCREEN.inp and prompt inputs for fumigation. ............................................... 34
Figure 20. AERSCREEN.INP and prompts inputs for output filename. ..................................... 35
Figure 21. AERSCREEN processing and stages. ........................................................................ 37
Figure 22. AERSCREEN start screen. ......................................................................................... 38
Figure 23. AERSCREEN validation page. .................................................................................. 40
Figure 24. Submenus for changing source parameters for a) point, capped or horizontal stack, b)
volume, c) rectangular area, d) circular area, and e) flare sources. .............................................. 41
Figure 25. Building downwash submenus for a) building downwash included and b) building
downwash not included................................................................................................................. 42
Figure 26. Terrain submenus for a) terrain heights included, b) terrain heights not included and
c) rectangular area sources. ........................................................................................................... 43
Figure 27. Meteorological data submenu for a) when not adjusting u* and b) when adjusted u* is
being used. .................................................................................................................................... 44
Figure 28. Fumigation submenus for various fumigation options. .............................................. 44
Figure 29. Meteorological file creation for monthly 12 sector AERSURFACE output. ............. 45
Figure 30. Sequence of AERMOD runs in PROBE for different surface characteristics
combinations. ................................................................................................................................ 48
Figure 31. Receptor radials for rectangular area sources. ............................................................ 50
Figure 32. ME pathway in the AERMOD runstream with WRDOTATE keyword and values for
various angles................................................................................................................................ 51
Figure 33. AERMOD run sequences for rectangular area source for seasonal 12 sector surface
characteristics. ............................................................................................................................... 52
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Figure 34. Receptor placement for point (including capped and horizontal stacks), flare, volume,
or circular area sources in FLOWSECTOR.................................................................................. 53
Figure 35. AERMOD sequence for seasonal 12 sector surface characteristics when processing
terrain and/or building downwash. ............................................................................................... 54
Figure 36. Flow vector (solid arrow) of 10 degrees and associated upwind surface roughness
sector for three surface roughness sectors (0 to 90, 90 to 225, 225 to 0). .................................... 54
Figure 37. Receptor skipping notification during FLOWSECTOR run, with notification of
missing elevations in AERMAP, and total number of receptors skipped for FLOWSECTOR and
REFINE......................................................................................................................................... 56
Figure 38. Plane view of building and stack orientation for example AERSCREEN run........... 63
Figure 39. a) land use pattern and sectors used for surface characteristics and b) terrain. The
circle represents the 1 km radius from the source......................................................................... 64
Figure 40. Contents of demlist.txt for terrain processing. ........................................................... 64
Figure 41. Contents of discrete_receptors.txt. ............................................................................. 65
Figure 42. Initial AERSCREEN title, units, and source type prompts. ....................................... 65
Figure 43. Source parameter inputs. ............................................................................................ 66
Figure 44. Initial building downwash prompts. ........................................................................... 66
Figure 45. Building parameter inputs. ......................................................................................... 67
Figure 46. Terrain parameter prompts. ........................................................................................ 67
Figure 47. Meteorological parameter prompts and inputs. .......................................................... 68
Figure 48. Fumigation prompts.................................................................................................... 68
Figure 49. Debug option input. .................................................................................................... 69
Figure 50. Output filename prompt and response. ....................................................................... 69
Figure 51. Data validation page. .................................................................................................. 70
Figure 52. Input data in AERSCREEN_EXAMPLE.LOG. ........................................................ 71
Figure 53. Surface characteristics processing and meteorological files creation. ....................... 72
Figure 54. AERMAP processing and elevation of source. .......................................................... 73
Figure 55. AERSCREEN_EXAMPLE.LOG records for AERMAP processing for
FLOWSECTOR. ........................................................................................................................... 73
Figure 56. Status of AERMAP processing for FLOWSECTOR. ................................................ 74
Figure 57. AERSCREEN_EXAMPLE.LOG summary of AERMAP.OUT warning and error
messages. ...................................................................................................................................... 75
Figure 58. Partial AERMAP output for FLOWSECTOR. ......................................................... 75
Figure 59. AERSCREEN processing during FLOWSECTOR.................................................... 76
Figure 60. Partial AERMOD.INP file used in FLOWSECTOR for 20 degree flow vector. ....... 77
Figure 61. AERSCREEN_EXAMPLE.LOG partial output of AERMOD.OUT checks for
FLOWSECTOR. ........................................................................................................................... 78
Figure 62. Status of AERMAP processing for REFINE.............................................................. 79
Figure 63. Partial AERMOD.INP file for REFINE processing. .................................................. 80
Figure 64. REFINE messages. ..................................................................................................... 80
Figure 65. Fumigation and final AERSCREEN messages. .......................................................... 81
Figure 66. Overall maximum, maximum ambient boundary concentration, and maximum
inversion break-up fumigation concentration statistics. ............................................................... 82
Figure 67. AERSCREEN_EXAMPLE.OUT section with source and building information. ..... 83
Figure 68. FLOWSECTOR results in AERSCREEN_EXAMPLE.OUT. .................................. 84

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Figure 69. Meteorological data associated with maximum FLOWSECTOR concentration and
ambient boundary concentration. .................................................................................................. 86
Figure 70. Summary of maximum concentrations by distance in
AERSCREEN_EXAMPLE.OUT. ................................................................................................ 87
Figure 71. Maximum concentration impact, ambient boundary, and inversion break-up
fumigation concentration summaries in AERSCREEN_EXAMPLE.OUT. ................................ 88
Figure 72. Output of aerscreen_example_max_conc_distance.txt. ............................................. 89
Figure 73. Partial output of aerscreen_example_concentrations.txt. ........................................... 90
Figure 74. Partial output of aerscreen_example_fumigate_debug.txt showing effective plume
height calculations. ....................................................................................................................... 91
Figure 75. Partial output of aerscreen_example_fumigate_debug.txt showing concentration
calculations. .................................................................................................................................. 92
Figure 76. Header portion of new AERSCREEN.INP file. ......................................................... 94




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                                                                       Tables

Table 1. MAKEMET prompts and example values for the first month and surface roughness
sector and last month and surface roughness sector for monthly 12 sector AERSURFACE output.
....................................................................................................................................................... 46
Table 2. Variables listed in max_conc_distance.txt..................................................................... 61
Table 3. Inputs for example AERSCREEN run.......................................................................... 62
Table 4. Seasonal surface characteristics by sector. .................................................................... 63




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1. Overview of AERSCREEN


AERSCREEN is EPA’s recommended screening-level air quality model based on AERMOD
(U.S. EPA, 2021a). The AERSCREEN model consists of two main components: 1) the
MAKEMET program which generates a site-specific matrix of meteorological conditions for
input to the AERMOD model; and 2) the AERSCREEN command-prompt interface program.
AERSCREEN interfaces with MAKEMET for generating the meteorological matrix, but also
interfaces with AERMAP (U.S. EPA, 2018) and BPIPPRM (Schulman et al. 2000; U.S. EPA,
2004) to automate the processing of terrain and building information respectively, and interfaces
with the AERMOD model utilizing the SCREEN option to perform the modeling runs.
AERSCREEN interfaces with version 09292 and later versions of AERMOD and will not work
with earlier versions of AERMOD. The AERSCREEN program also includes averaging time
factors for worst-case 3-hr, 8-hr, 24-hr and annual averages.

The screening mode of the current version of AERMOD, which is controlled by the SCREEN
option on the CO MODELOPT card, forces the model calculations to represent values for the
plume centerline, regardless of the source-receptor-wind direction orientation. This option is
included in AERMOD to facilitate the use of the model in a screening mode to estimate worst-
case impacts. Since the screening option in AERMOD is designed to be used with a non-
sequential meteorological data file representing a matrix of conditions, currently generated by
the MAKEMET program, the SCREEN option also forces the use of the NOCHKD option even
if NOCHKD is not included on the MODELOPT card. The NOCHKD option suspends the
checks made within AERMOD for proper date sequences in the surface and profile
meteorological input data files. The SCREEN option also restricts the averaging period options
to 1-hour averages only on the CO AVERTIME card.

Given these two basic components of AERSCREEN, the AERMOD model can be run in a
screening mode by either: 1) using the AERSCREEN command-prompt interface; or 2) using the
stand-alone MAKEMET program to generate the matrix of meteorological conditions and
running AERMOD directly with the SCREEN option. The first approach automates much of the
processing for the user, including building and terrain processing, while the second approach
gives the user more flexibility for defining the receptor network to be used in the screening
analysis and may be more appropriate in certain situations, especially in very complex terrain
settings. These two options for running AERMOD in a screening mode will not necessarily
produce the same results. This is because the results for the stand-alone application of
AERMOD with MAKEMET-generated meteorology will be determined by the user-specified
receptor network, whereas the AERSCREEN program performs a more precise search to isolate
the receptor distance with the highest impact, similar to the automated distance option in
SCREEN3 (U.S. EPA, 1995). In general, the AERSCREEN program should produce slightly
more conservative results than stand-alone AERMOD with MAKEMET data, depending on the
receptor resolution used for the latter.


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Before running AERSCREEN, users should consult and become familiar the following:
   • AERMOD User’s Guide (U.S. EPA, 2021a)
   • AERMAP User’s Guide (U.S. EPA, 2018)
   • AERMET User’s Guide [for surface characteristics tables] (U.S. EPA, 2021b)
   • BPIPPRM User’s Guide (U.S. EPA, 2004)
   • Guideline on Air Quality Models (Appendix W) (U.S. EPA, 2016)
   • AERSURFACE User’s Guide (U.S. EPA, 2020)
   • AERMOD Implementation Guide (U.S., EPA, 2021c)
   • Screening Procedures for Estimating the Air Quality Impact of Stationary Sources (U.S.
       EPA, 1992)

The above documents and other support documents can be found at the AERMOD modeling
page of the Support Center for Regulatory Atmospheric Modeling (SCRAM) page at:
https://www3.epa.gov/ttn/scram/dispersion_prefrec.htm#aermod.


1.1 Description of AERSCREEN


As stated above, AERSCREEN is an interactive command-prompt application that interfaces
with MAKEMET for generating the meteorological matrix, but also interfaces with AERMAP
and BPIPPRM to automate the processing of terrain and building information, and interfaces
with the AERMOD model utilizing the SCREEN option to perform the modeling runs. The
AERSCREEN program also includes averaging time factors for worst-case 3-hr, 8-hr, 24-hr and
annual averages. The AERSCREEN program is currently limited to modeling a single point
(vertical uncapped stack), capped stack, horizontal stack, rectangular area, circular area, flare, or
volume source.

Inputs or options to AERSCREEN are:
   • Source parameters for point, rectangular area, circular area, volume, capped stack,
        horizontal stack or flare sources
   • Building downwash information for point, capped stack, horizontal stack, and flare
        sources
   • Ability to model NOx to NO2 conversion
            o Plume Volume Molar Ratio (PVMRM) (Hanrahan, 1999a and 1999b) or
            o Ozone Limiting Method (OLM)
            o Input of representative ozone background concentration
   • Ability to use terrain heights for source and receptors via AERMAP
   • Specify ambient minimum and maximum temperatures for MAKEMET
   • Specify minimum wind speed and anemometer height for MAKEMET
   • Specify surface characteristics for input to MAKEMET by the following methods:
            o user-defined single values for albedo, Bowen ratio, and surface roughness (no
                temporal or spatial variation in surface characteristics)
            o AERMET seasonal tables (temporal variation only)
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           o Values listed in an external file, either an AERSURFACE (U.S. EPA, 2020)
               output file or surface characteristics listed in an AERMET stage 3 input file
   •   Ability to adjust surface friction velocity based on AERMET algorirthms
   •   Probe distance (maximum downwind distance) of receptors
   •   Use of flagpole receptors and define flagpole height
   •   Specify urban or rural source and urban population if urban source
   •   Minimum ambient distance for ambient air receptors
   •   Up to ten discrete receptor distances in a user supplied text file
   •   Plume fumigation due to inversion break-up
   •   Shoreline fumigation of plume
   •   Performs error checks on AERSCREEN inputs, AERMOD output and/or AERMAP
       output
   •   Calculate maximum concentration by distance
   •   Debug option to output intermediate output from PROBE or FLOWSECTOR as well as
       intermediate fumigation calculations.
   •   Search routine to find overall worst case scenario (maximum 1-hour concentration)

AERSCREEN automatically provides impacts for other averaging periods using scaling ratios.
The averaging period ratios currently implemented in AERSCREEN are as follows (SCREEN3
factors are shown for comparison):

             •   3-hour    fixed ratio of 1.00       0.90
             •   8-hour    fixed ratio of 0.90       0.70
             •   24-hour   fixed ratio of 0.60       0.40
             •   Annual    fixed ratio of 0.10       0.08

For area sources (rectangular and circular), the averaging factors are based on guidance in
Section 4.5.4 of the EPA screening guidance document (U.S. EPA, 1992). For area sources, the
3, 8, and 24-hour average concentrations are equal to the 1-hour average calculated by
AERMOD in screening mode. No annual average concentration is calculated.


1.1.1 Changes to AERSCREEN

The original version of AERSCREEN is version 11060. Following is a list of changes since that
version.

Version 11076
   1. Modified subroutine MAKETERRAIN to change the variable XDIST to always be 1.1
       times the probe distance for the DOMAINXY keyword that goes into AERMAP. In
       version 11060, for the FLOWSECTOR stage of AERSCREEN, XDIST was set to 1.1
       times the probe distance while in FLOWSECTOR it is set to 1.1 times the final distance.
       In complex terrain, this change in DOMAINXY can affect hill height scales, affecting
       concentrations.

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Version 11126
   1. Modified subroutine MAKETERRAIN to accommodate the 12-character source
       identifier for AERMAP version 11103.
   2. Modified subroutine READINP to set the discrete receptor use flag to N and discrete
       receptor file to "NA" when the discrete receptor data section is missing in
       AERSCREEN.INP

Version 14147
   1. Modified subroutines MAKETERRAIN and MAKEGRID to include a new variable,
       REFDIST for calculating receptors for the REFINE stage. Previously, the variable
       NUMPT was used in these subroutines to represent the number of receptor points for the
       PROBE and FLOWSECTOR stages and distance for the REFINE stage. REFDIST was
       created to avoid confusion with different meanings of NUMPT. REFDIST is also set to
       the probe distance if REFDIST exceeds the probe distance.
   2. Modified subroutine MAKEINPUT to eliminate a blank line as the first line of the
       AERMOD input file. This makes AERSCREEN compatible with AERMOD version
       14134 and later due to the skipping of blank lines in AERMOD (see miscellaneous
       change #3 of AERMOD MCB #10).
   3. Modified subroutine FINDMAX to read the AERMOD version number from
       AERSCREEN.FIL so that it is independent of the AERMOD version. Previous versions
       of AERSCREEN read the version number using a fixed format that changed with
       AERMOD 12345. AERSCREEN no longer uses a fixed format to read the version
       number and is flexible for later AERMOD versions.
   4. Modified subroutine READINP to set the discrete receptor use flag DISCFLAG to N
       instead of setting the logical variable DISCDAT to N. Previous versions of
       AERSCREEN were setting the wrong variable (DISCDAT).

Version 15181
   1. Added subroutines FUMINP, FUMIGATE, INVMAX, SHORELINE, SHOREMAX,
       RECALCPLUME, and TIBL to support inversion break-up and shoreline fumigation
       calculations
   2. Added subroutine SUBSETMET to create matrix of hours with meteorological conditions
       of F stability and stack top wind speed of 2.5 m/s for fumigation calculations.
   3. Added fumigation inputs including distance to shoreline, optional direction to shoreline,
       and option to run or not run full AERSCREEN in subroutine READINP.
   4. Added fumigation error check flags to subroutine CHECKDAT.
   5. Modified subroutine VALIDATE AND WRITETOLOG to add fumigation options
   6. Added optional debug option to output PROBE, FLOWSECTOR, and fumigation
       calculations.
   7. Updated subroutine PLUMEHGT to include plume height calculations for stable
       conditions.
   8. Updated subroutine MAKEMET2 to include optional u* adjustment prompt for
       MAKEMET. At this time, this prompt is always set to no (do not include adjustment).
   9. Eliminated numerous system calls of copying and deleting files by using write statements
       and close statements. This is to make code more portable across operating systems.

                                              4
Version 16216
   1. Corrected a bug in subroutine SUBSETMET related to the surface meteorological data
       filename.
   2. Added the option to specify the use of adjusted u* in subroutine READINP, VALIDATE,
       WRITETOLOG, METDATA, MAKEMET2, and OUTPUT.
   3. Modified subroutine OUTPUT to only output non-zero minimum building widths when
       using user supplied building files.
   4. Removed BETA flags for POINTCAP and POINTHOR source types in subroutine
       MAKEINPUT.

Version 21112
   1. Set the inversion fumigation concentration to zero if the maximum distance for inversion
       breakup is less than 2 km in subroutine INVMAX. This is to make AERSCREEN
       consistent with fumigation in SCREEN3.
   2. Add debug statement alerting user that shoreline concentration is set to zero if the
       distance is less than 200 m in subroutine SHOREMAX.
   3. Initialize the variable DEFAULT to .TRUE. so that AERSCREEN writes the default
       output filenames if an error occurs before the program obtains the output filename.
1.2 Description of MAKEMET


The MAKEMET program generates a matrix of meteorological conditions, in the form of
AERMET-ready surface (AERSCREEN.sfc) and profile (AERSCREEN.pfl) files, based on user-
specified surface characteristics, ambient temperatures, minimum wind speed, and anemometer
height. See the AERMET User’s Guide (U.S. EPA, 2021b) for file formats. The current version
of MAKEMET also allows the user to specify the minimum wind speed to include in the matrix
and the anemometer height as well. Beginning with version 15181, MAKEMET has the
capability to include the adjustment to surface friction velocity, u*, that is also a part of
AERMET. These options have been included to facilitate comparisons of AERSCREEN
estimates to estimates from AERMOD in a refined mode to eliminate differences that may be
due to either the minimum wind speed in the refined data or the anemometer height. The
suggested default values for routine application of MAKEMET are 0.5 m/s for the minimum
wind speed and 10 meters for the anemometer height.

MAKEMET allows the user to specify more than one set of surface characteristics and ambient
temperatures, such as for seasonal or monthly variations, and will concatenate the resulting
meteorological matrices into single surface and profile files. For AERSCREEN, this option is
not used and separate files are created for seasonal or monthly variations in surface
characteristics. No variation in minimum and maximum temperature is done in MAKEMET.
MAKEMET also allows the user to specify a single wind direction or a range of wind directions
for the meteorological matrix. This option may be useful for applications involving building
downwash to ensure that building dimensions for all sectors are included in the screening
analysis (the treatment of building downwash in the AERSCREEN program is described in

                                              5
Section 3.2.2). However, in AERSCREEN processing, the wind direction is set to a single
direction of 270 degrees.

MAKEMET can be run from the command-prompt, with the prompts in Figure 1 for user input.


 ENTER SFC MET FILE NAME

 ENTER PFL MET FILE NAME

 ENTER MIN. WS (M/S)

 ENTER ANEM HT (M)

 ENTER OPTION TO ADJUST U* (Y=adjust,N=no adjustment)

 ENTER NUMBER OF WIND DIRECTIONS

 If the user enters one for the number of wind directions
 ENTER WIND DIRECTION

 Otherwise
 ENTER STARTING WIND DIRECTION

 ENTER CLOCKWISE WIND DIRECTION INCREMENT

 ENTER MIN AND MAX AMBIENT TEMPS IN KELVIN

 ENTER ALBEDO

 ENTER BOWEN RATIO

 ENTER SURFACE ROUGHNESS LENGTH IN METERS

 DO YOU WANT TO GENERATE ANOTHER MET SET THAT WILL BE
 APPENDED TO CURRENT FILE?
 [TYPE EITHER "Y" OR "y" FOR YES; OR HIT "ENTER" TO EXIT

 If ("Y" or "y") then the program loops through prompts 7 through 10 for each additional data set (e.g. seasonal).
Figure 1. User prompts for MAKEMET.

The MAKEMET program has a long complex history, dating back over 10 years. Suffice it to
say that the version of MAKEMET supplied with AERSCREEN operates in the following
manner. As mentioned earlier, MAKEMET generates a matrix of meteorological conditions for
application of AERMOD in a screening mode and output the results in the form of AERMOD-
ready surface and profile meteorological data files. The matrix is generated based on looping
through a range of wind speeds, cloud covers, ambient temperatures, solar elevation angles, and
convective velocity scales (w* for convective conditions only) for user-specified surface
characteristics (Zo, Bo, r). For stable cases, the mechanical mixing height (Zim) is calculated
based on the friction velocity, u*. A loop through Zim factors (multiplied times the initial value
calculated form u*) is also included to account for smoothing of Zim that occurs with refined
                                                            6
AERMET data. Stable transition cases with solar angle greater than zero but less than the
critical solar angle (ACRIT) are also included in the matrix.

The program calculates u*, Monin-Obukhov length (L), and Zim for each combination in the
matrix, and also calculates the convective mixing height (Zic) based on w* for convective cases.
The program uses subroutines from AERMET (U.S. EPA, 2021b) to calculate boundary layer
parameters for each combination in the matrix. The program generates a log file, called
MAKEMET.LOG, which summarizes the inputs selected for that run, and the number of “hours”
in the final screening matrix for each set of surface characteristics. An effort has been made to
optimize the MAKEMET program for AERMOD screening applications by eliminating
combinations that are unnecessary in terms of identifying worst-case impacts, based on a wide
range of tests comparing screening to refined AERMOD estimates (which are briefly
summarized below). The number of “hours” per set of surface characteristics will typically be
around 300-400, but will vary depending on the user inputs. The number will tend to be larger
for applications with lower surface roughness due to the internal checks made to eliminate
unnecessary combinations.

MAKEMET uses the following scheme to assign dates for each of the “hours” in the
meteorological matrix. The default starting year for the data is 10, and the year is incremented
by 10 for each additional data set generated. Thus, for seasonal data files, the first season date
will start with a '1', second season will start with a '2', etc. The hour is used to distinguish
between stable and convective conditions, with hours 01 through 11 indicating stable hours, and
hours 12 through 24 indicating convective hours. Note that for monthly data sets and/or for large
numbers of wind directions (greater than 36), duplicate dates may be generated. A warning
message is written to the log file in these cases. AERMOD will still run since the NOCHKD
option is invoked, but determining which conditions produced the worst-case results could
become problematic. In addition to the required variables for input to AERMOD, the surface file
generated by MAKEMET also includes five columns of integer variables that provide the loop
indices for each of the loops in the met matrix corresponding to each "hour" of screening
meteorology. These indices can be used to analyze the frequency of occurrence for various
combinations within the meteorological matrix resulting in the controlling (highest)
concentration.

AERSCREEN provides three options for surface characteristics inputs for generating the
screening meteorology. One option allows for user-specified surface characteristics – albedo,
Bowen ratio, and surface roughness (no spatial or temporal variation), the second option is to use
seasonally varying surface characteristics for generic land use classifications based on Tables 4-
1, 4-2, and 4-3 of the AERMET User’s Guide (U.S. EPA 2021b). The third option is to input the
name of an external file such as an AERSURFACE (U.S. EPA, 2020) output file or AERMET
stage 3 input file that contains surface characteristics. Monthly, seasonal, and annual output for
one sector or multiple sectors is allowed with the third option. AERSCREEN will setup and run
the MAKEMET program to generate the screening meteorological data for input to AERMOD.
AERSCREEN will run MAKEMET for each combination of temporal period and spatial sector
of the surface characteristics. If AERSURFACE output is used, AERSCREEN does not call
AERSURFACE, so the user must run AERSURFACE prior to running AERSCREEN.

                                                7
1.3 Differences with SCREEN3


The three areas where AERSCREEN deviates significantly from SCREEN3 and will, thus, be
the most difficult for first time users are:

   1) Building wake effects – AERSCREEN utilizes all the advantages of PRIME (Schulman
      et al., 2000) including stacks detached from the building. This requires three additional
      pieces of information from the user beyond the normal building height and dimensions.
      The additional information is orientation of the maximum dimension relative to north,
      angle relative to north of the stack and, distance between the stack and building center.
      AERSCREEN will use this information to setup and run the BPIPPRM program and extract
      the information needed for the AERMOD model. More downwash details can be found in
      Section 2.2.

   2) Meteorology – AERSCREEN provides three options for generating the screening
      meteorology. One option allows for user-specified surface characteristics – albedo,
      Bowen ratio, and surface roughness (no temporal or spatial variation) – the second option
      is to use seasonally varying surface characteristics for generic land use classifications
      based on Tables 4-1, 4-2, and 4-3 of the AERMET User’s Guide. The third option is to
      use surface characteristics listed in an external file such as an AERSURFACE output file
      or AERMET stage 3 input file. The user enters the name of the file. The user also
      specifies the overall minimum and maximum ambient temperatures. AERSCREEN will
      setup and run the MAKEMET program to generate the screening meteorological data for
      input to AERMOD. More details about meteorology can be found in Section 2.3.

   3) Terrain – AERSCREEN provides the option for incorporating terrain impacts on the
      screening analysis. The user must create a file called demlist.txt. The first line of this
      file describes the type of terrain file being used. The file type must be DEM or NED.
      DEM refers to any DEM file type and NED refers to National Elevation Dataset. The
      third line of the file lists the location of the NAD conversion files and the fourth line
      begins the list of terrain files with each file on a separate line. When AERSCREEN is
      run, the user will be prompted to provide the source coordinates and associated NAD
      datum. AERSCREEN will then setup the necessary input file for AERMAP, run
      AERMAP, and extract the information needed for the AERMOD model. More terrain
      processing details can be found in Section 2.4

Given the use of surface characteristics and terrain, it is important that the user know the exact
coordinates of the source, i.e., stack or center location of volume or area source.




                                                 8
2. AERSCREEN features


As noted in Section 1.1, AERSCREEN has many features and options available to the user. In
this section, the features and inputs to the restart file, AERSCREEN.INP, are described. When
running AERSCREEN from a restart file, the file must be named AERSCREEN.INP or
AERSCREEN will automatically begin prompting the user for data. The prompts used to enter
the data interactively are described in each relevant section as well. Prompts are not necessarily
shown in the order in which they appear but in the order for the parameters shown in
AERSCREEN.INP for each data section. The prompts described are based on metric units.
When processing data from the input file, all units are assumed to be metric. Some variables
listed below are not requested when using the prompts to enter data, but are automatically
defaulted, such as when processing a rectangular area source, volume source, or circular area
source. In the case of a rectangular area source, terrain use and downwash are automatically set
to “no” and the user is not prompted for the choice of terrain processing and source coordinates.
For all three source types, downwash is automatically set to “no” and downwash information is
not requested. When reading data from the input file, if one of the data sections (source,
building, terrain, meteorology, etc.) is missing, AERSCREEN will notify the user and stop
processing. Also, if the source data is listed after the building, terrain, or miscellaneous data,
AERSCREEN will alert the user and stop processing. This is done because the source type is
needed to determine if parameters must be reset in the building or terrain sections, such as
resetting building downwash to “no” if an area or volume source is being processed. Also, if
data is missing or invalid (such as negative emission rate) when reading AERSCREEN.INP,
AERSCREEN alerts the user and stops processing.


2.1 Source inputs


AERSCREEN can be used for a single point, flare, capped stack, horizontal stack, volume,
rectangular area source, or circular area source. Below are listed the source types with required
input variables and example values from the first line of the AERSCREEN.INP file. Building
downwash is allowed for the point, capped stack, horizontal stack, and flare sources but not for
volume or area (rectangular or circular) sources. Terrain processing is allowed for all sources
except rectangular area sources. For all source types, emission rates are in g/s or lb/hr. For area
source types, AERSCREEN calculates the emission rate per unit area, the required input for
AERMOD.




                                                 9
2.1.1 Point, capped stacks and horizontal stack sources


Stack parameters for point (vertical stacks with no caps), capped stacks, and horizontal stacks are
the same. Point sources are denoted by the term “** STACK DATA “in the input file in the line
above the source parameters. Capped stacks are denoted by the term “** POINTCAP DATA” in
the input file and horizontal stacks are denoted by the term “** POINTHOR DATA” in the input
file. Source inputs for these three source types are, with English and metric units in parentheses:
     • emission rate (lb/hr or g/s)
     • stack height (feet or meters)
     • stack diameter (inches or meters)
     • stack temperature (degrees Fahrenheit or Kelvin)
     • and stack velocity (ft/s or m/s) or flow rate (ACFM)

Note that stack velocity can be input as ft/s or m/s, regardless of using English or metric units for
other parameters. AERSCREEN.INP and prompt inputs (shown in italics) are shown in Figures
2 through 4 for point, capped stack and horizontal stacks, respectively. If a stack temperature of
zero (Fahrenheit or Kelvin) or negative stack temperature is entered, the entered temperature will
be used as a difference between the stack and ambient temperature. A negative number, such as
-10, implies that the stack is 10 degrees warmer than the ambient temperature.




                                                 10
                                  AERSCREEN.INP point source inputs
 ** STACK DATA     Rate Height Temp. Velocity Diam. Flow
 **          0.1896E+01 5.0902 353.7056 13.2662 0.6096 8204.
                                         Point source prompts inputs
 If the user enters “P” or “p” for point source:

 Enter Emission Rate (g/s):

 Enter Stack Height (meters):

 Enter Stack Diameter (meters):

 Enter Stack Temperature (K)
  Enter 0 for ambient temperature
  or a negative number for temperature difference ((K))
 between stack temperature and ambient temperature:

 Option (1) - Exit Velocity (m/s)
 Option (2) - Exit Velocity (ft/s)
 Option (3) - Flow Rate (ACFM)

 Enter Option for Flow Rate or Exit Velocity:

 If the user chooses option 1, the prompt is:

 Enter Exit Velocity (m/s):

 If the user chooses option 2, the prompt is:

 Enter Exit Velocity (ft/s):

 If the user chooses option 3, the prompt is:

 Enter Flow Rate (ACFM):
Figure 2. AERSCREEN.INP and prompts inputs for point sources.




                                                      11
                                AERSCREEN.INP capped stack source inputs
 ** POINTCAP DATA    Rate Height Temp. Velocity Diam. Flow
 **            0.1896E+01 5.0902 353.7056 13.2662 0.6096 8204.
                                      Capped stack source prompts inputs
 If the user enters “S” or “s” for capped stack source:

 Enter Emission Rate (g/s):

 Enter Stack Height (meters):

 Enter Stack Diameter (meters):

 Enter Stack Temperature (K)
  Enter 0 for ambient temperature
  or a negative number for temperature difference ((K))
 between stack temperature and ambient temperature:

 Option (1) - Exit Velocity (m/s)
 Option (2) - Exit Velocity (ft/s)
 Option (3) - Flow Rate (ACFM)

 Enter Option for Flow Rate or Exit Velocity:

 If the user chooses option 1, the prompt is:

 Enter Exit Velocity (m/s):

 If the user chooses option 2, the prompt is:

 Enter Exit Velocity (ft/s):

 If the user chooses option 3, the prompt is:

 Enter Flow Rate (ACFM):
Figure 3. AERSCREEN.INP and prompts inputs for capped stack sources.




                                                          12
                            AERSCREEN.INP horizontal stack source inputs
  ** POINTHOR DATA       Rate                    Height           Temp.   Velocity    Diam.    Flow
  **               0.1896E+01                    5.0902        353.7056    13.2662   0.6096   8204.
                                  Horizontal stack source prompts inputs
  If the user enters “H” or “h” for horizontal stack source:

  Enter Emission Rate (g/s):

  Enter Stack Height (meters):

  Enter Stack Diameter (meters):

  Enter Stack Temperature (K)
   Enter 0 for ambient temperature
   or a negative number for temperature difference ((K))
  between stack temperature and ambient temperature:

  Option (1) - Exit Velocity (m/s)
  Option (2) - Exit Velocity (ft/s)
  Option (3) - Flow Rate (ACFM)

  Enter Option for Flow Rate or Exit Velocity:

  If the user chooses option 1, the prompt is:

  Enter Exit Velocity (m/s):

  If the user chooses option 2, the prompt is:

  Enter Exit Velocity (ft/s):

  If the user chooses option 3, the prompt is:

  Enter Flow Rate (ACFM):
Figure 4. AERSCREEN.INP and prompts inputs for horizontal stack sources.


2.1.2 Flares


    Flare sources are denoted by the term “** FLARE DATA” in the input file in the line above
the source parameters. Flare source inputs are, with English and metric units:
    • emission rate (lb/hr or g/s)
    • stack height (feet or meters)
    • total heat release rate (cal/sec)
    • radiative heat loss fraction

    The heat loss fraction can be user selected or the SCREEN3 default value of 0.55. For
information about heat loss fractions, see Leahey and Davies (1984). AERSCREEN will process

                                                          13
the flare in AERMOD as a POINT source type. For the exit velocity and exit temperature,
AERSCREEN defaults these values to 20 m/s and 1,273 K, respectively as done in SCREEN3
(U.S. EPA, 1995). The stack diameter and effective stack height used in AERMOD are
calculated from the inputs as:

𝐷 = 9.88 × 10−4 × √𝐻𝑅 × (1 − 𝐻𝐿)                                                             (1)

ℎ𝑒𝑓𝑓 = 𝐻𝑠 + 4.56 × 10−3 × 𝐻𝑅 0.478                                                           (2)

Where D is effective stack diameter, HR is the heat release rate, HL is the heat loss fraction, Heff
is effective stack height and Hs is the stack height entered by the user.

AERSCREEN.INP and prompt inputs (in italics) are shown in Figure 5.

                                    AERSCREEN.INP flare source inputs
  ** FLARE DATA                  Rate            Height          Heat   HeatLoss
  **                       0.1000E+03           35.0000    0.1000E+08      0.550
                                          Flare source prompts inputs
  If the user enters “F” or “f” for flare source:

  Enter Emission Rate (g/s):

  Enter Flare Stack Height (meters):

  Enter Total Heat Release Rate (cal/sec):

  Enter Radiative Heat Loss Fraction –
  <Enter> for default value of 0.55:
Figure 5. AERSCREEN.INP and prompts inputs for flare sources.


2.1.3 Volume sources


Volume sources are denoted by the term “** VOLUME DATA” in the input file in the line
above the source parameters. Volume source inputs are, with English and metric units:
   • emission rate (lb/hr or g/s)
   • release height, i.e. center of volume (feet or meters)
   • initial lateral dimension of the volume (feet or meters)
   • initial vertical dimension of the volume (feet or meters)

AERSCREEN.INP and prompt inputs (in italics) are shown in Figure 6.




                                                          14
                                AERSCREEN.INP volume source inputs
  ** VOLUME DATA                Rate           Height        Syinit   Szinit
  **                      0.1000E+03           2.0000        1.5000   3.0000
                                      Volume source prompts inputs
  If the user enters “V” or “v” for volume source:

  Enter Emission Rate (g/s):

  Enter Center of Volume Height (meters):

  Enter Initial Lateral Dimension (meters):

  Enter initial Vertical Dimension (meters):
Figure 6. AERSCREEN.INP and prompts inputs for volume sources.


2.1.4 Rectangular area sources


Rectangular area sources are denoted by the term “** AREA DATA” in the input file in the line
above the source parameters. Rectangular area source inputs are, with English and metric units:
   • emission rate (lb/hr or g/s)
   • release height above ground (feet or meters)
   • long and short dimensions of area (feet or meters)
   • initial vertical dimension of plume (feet or meters)

As previously noted, the emission rate is in g/s or lb/hour, not emission rate per unit area as
entered in AERMOD input files. AERSCREEN automatically calculates the emission rate per
unit area to input into AERMOD. The angle of the source relative to north is automatically set to
0 degrees. Note that the long dimension of the area source is in the x-direction and short
dimension in the y-direction. AERSCREEN.INP and prompt inputs (in italics) are shown in
Figure 7. For rectangular area sources, AERMOD uses the non-default FASTAREA keyword on
the MODELOPT keyword in the CO pathway of the AERMOD.INP file.




                                                        15
                                AERSCREEN.INP rectangular area inputs
  ** AREA DATA                   Rate            Height          Length      Width   Angle     Szinit
  **                       0.1000E+03            2.0000        500.0000   200.0000     0.0       1.50
                                  Rectangular area source prompts inputs
  If the user enters “A” or “a” for rectangular area source:

  Enter Emission Rate (g/s):

  Enter Release Height Above Ground (meters):

  Enter Long Side of Area Source (meters):

  Enter Short Side of Area Source (meters):

  Enter Initial Vertical Dimension (meters):
Figure 7. AERSCREEN.INP and prompts inputs for rectangular area sources.


2.1.5 Circular area sources


Circular area sources are denoted by the term “** AREACIRC DATA” in the input file in the
line above the source parameters. Circular area source inputs are, with English and metric units:
    • emission rate (lb/hr or g/s)
    • release height above ground (feet or meters)
    • radius of circle (feet or meters)
    • initial vertical dimension of plume (feet or meters)

As with rectangular area sources, the emission rate is in g/s or lb/hour, not emission rate per unit
area. AERSCREEN.INP and prompt inputs (in italics) are shown in Figure 8. For circular area
sources, AERMOD uses the non-default FASTAREA keyword on the MODELOPT keyword in
the CO pathway of the AERMOD.INP file.

                               AERSCREEN.INP circular area source inputs
  ** AREACIRC DATA       Rate                    Height          Radius   NVerts      Szinit
  **               0.1000E+03                    2.0000        250.0000       20        1.50
                                    Circular area source prompts inputs
  If the user enters “C” or “c” for circular area source:

  Enter Emission Rate (g/s):

  Enter Release Height Above Ground (meters):

  Enter Radius of AREACIRC Source (meters):

  Enter Initial Vertical Dimension (meters):
Figure 8. AERSCREEN.INP and prompts inputs for circular area sources.



                                                            16
2.1.6 NOx to NO2 conversion


Beginning with version 11060, AERSCREEN allows the option to include NOx to NO2
conversion either by using the Plume Volume Molar Ratio Method (PVMRM) or the Ozone
Limiting Method (OLM). See Section 2.4 of the AERMOD User’s Guide Addendum for more
information about PVMRM and OLM and Hanrahan (1999a and 1999b) for background on
PVMRM.

When entering data via the prompts, the user is asked to enter an option for modeling NOx to
NO2 conversion:

   1. No chemistry or pollutant is not NO2
   2. Use Ozone Limiting Method (OLM)
   3. Use Plume Volume Molar Ratio Method (PVMRM)

If option two or three is chosen, the user is prompted for the NO2/NOx in-stack ratio (AERMOD
card CO NOSTACK) and a representative ozone background concentration (AERMOD card CO
OZONEVAL). The NO2/NOX in-stack ratio can range from zero to one and units of the
background concentration can be parts per million (ppm), parts per billion (ppb) or micrograms
per cubic meter (g/m3). For PVMRM the NO2EQUIL ratio is set at the default value of 0.9.
For OLM use, since only one source is being modeled, the OLMGROUP keyword is not needed.

When entering data via AERSCREEN.INP, the user can specify NOx to NO2 conversion by
setting the appropriate keywords in the CO pathway of the AERMOD runstream file portion of
AERSCREEN.INP. PVMRM or OLM must be included on the MODELOPT keyword string,
POLLUTID must be NO2, NO2STACK must be specified with a ratio, and the background
ozone concentration and units must be specified using OZONEVAL. Figure 9 shows the inputs
using AERSCREEN.INP or interactive prompts.




                                              17
                          AERSCREEN.INP NOx to NO2 chemistry inputs
   MODELOPT CONC SCREEN OLM
   POLLUTID NO2
   NO2STACK 0.9000
   OZONEVAL    0.4000 UG/M3
   MODELOPT CONC SCREEN PVMRM
   POLLUTID NO2
   NO2STACK 0.9000
   OZONEVAL    0.4000 UG/M3
                                 NOx to NO2 chemistry prompts inputs

  Enter an option for modeling NO2 chemistry
  1) No chemistry or pollutant is not NO2
  2) Use Ozone Limiting Method (OLM)
  3) Use Plume Volume Molar Ratio Method (PVMRM)

  If the user enters “2” or “3”
  Enter in-stack NO2/NOx ratio ( 0 to 1.0):

  Enter concentration units for representative ozone concentration
  1) Micrograms per cubic meter (ugm/m^3)
  2) Parts per million (ppm)
  3) Parts per billion (ppb)

  Enter ozone concentration:
Figure 9. AERSCREEN.INP and prompts inputs for NOx to NO2 conversion.


2.1.7 Other inputs


Other inputs in the source input prompts are urban/rural classification and minimum ambient
distance. These are discussed in more detail in Section 2.7.


2.2 Downwash


   Several parameters are needed by AERSCREEN for input into BPIPPRM. These are:
   • Include downwash (Y=use building downwash, N=no downwash)
   • Option to use an existing BPIPPRM input file or,
   • Building height (feet or meters)
   • Maximum building horizontal dimension (feet or meters)
   • Minimum building horizontal dimension (feet or meters)
   • Degrees from North of maximum building horizontal dimension (0-179 degrees)
   • Degrees from North of stack location relative to building center (0-360 degrees)
   • Distance between stack and building center (feet or meters)



                                                       18
Building parameter data are denoted by the term “** BUILDING DATA” in the input file in the
line above the building dimensions. These inputs are listed in the second block of data of
AERSCREEN.INP (Figure 10) and must be entered in the AERSCREEN.INP file after the
emissions data or AERSCREEN will stop processing. The order of variables is as listed above.
Prompts for building downwash are also shown in Figure 10. When entering data via the
prompts, building prompts will only appear when processing point, capped stack, horizontal
stacks, or flare sources. Building dimensions are in feet or meters. Angles are in degrees
relative to North (0 to 360 degrees). An example building/stack configuration is shown in Figure
11. When entering building parameters, either through the building data line or prompts shown
in Figure 10, the parameters are for a single tier rectangular or square shaped building. If the
user wishes to use downwash for multiple buildings, tiers, or more complicated geometries, the
user can enter a BPIPPRM input filename at the prompts (“Use pre-existing BPIPPRM input
file”) or in the CO pathway of the AERSCREEN input file using the TITLETWO keyword. If a
BPIPPRM input filename is entered, AERSCREEN will use the parameters from the file but will
not overwrite parameters from the building data block. If a pre-existing BPIPPRM input file is
used, the process, line 2 of the BPIPPRM input file, must be set to ‘P’ or ‘p’ for PRIME
downwash and only one stack located within the file or AERSCREEN will abort.




                                              19
                  AERSCREEN.INP building inputs on BUILDING DATA line
 ** BUILDING DATA             BPIP    Height    Max dim.     Min dim.     Orient.     Direct.    Offset
 **                            Y     34.0000    120.0000      60.0000     90.0000     26.6000   45.0000
                    AERSCREEN.INP building BPIPPRM input filename line
 CO STARTING
    TITLEONE flare
    TITLETWO BUILDING.INP
 **            REFINE STAGE 3
    MODELOPT CONC SCREEN
    AVERTIME 1
    POLLUTID OTHER
    RUNORNOT RUN
 CO FINISHED
                                          Building prompts inputs
 Include Building Downwash? (y/n):

 If user enters “y” or “Y”:

 Use pre-existing BPIPPRM input file? (y/n):

 If user enters “y” or “Y” for pre-existing BPIPPRM input file:

 Enter user created BPIPPRM input file:

 If user enters “n” or “N” for pre-existing BPIPPRM input file:

 Enter Building Height (meters):

 Enter Maximum Horizontal Building Dimension (meters):

 Enter Minimum Horizontal Building Dimension (meters):

 Enter Maximum Building Dimension Angle to True North (0 - 179 degees):

 Enter Direction of Stack from Building Center (0 - 360 degrees):

 Enter Distance Between Stack and Building Center (meters):

 If user enters “n” or “N” for building downwash use then no prompts are processed.
Figure 10. AERSCREEN.INP and prompts inputs for building inputs.




                                                       20
Figure 11. Stack and building orientation for a building oriented 90 degrees to north and
stack oriented 45 degrees to north.


2.3 Meteorology and surface characteristics


For inputs to MAKEMET, the user enters the following:

   •   Minimum and maximum ambient air temperatures (Fahrenheit or Kelvin)
   •   Minimum wind speed (m/s)
   •   Anemometer height (m)
   •   Surface characteristics type (user-entered, AERMET tables, or surface characteristics
       listed in an external file)

When entering data via the prompts, the user can choose to enter default values for temperatures,
wind speed, and anemometer height (see Figure 12). If using non-default values for
temperatures, the record minimum and maximum temperatures for the area containing the source
should be entered. If using a non-default value for the minimum wind speed, a wind speed less
than 0.5 m/s is allowed. When entering surface characteristics, if the user chooses to utilize user-
                                                21
entered single value surface characteristics, the user will be prompted for those values. If the
user chooses to use AERMET seasonal tables, the user will be prompted for land use type and
surface moisture (average, dry, or wet). If the user chooses to use an external file, i.e.
AERSURFACE output or AERMET stage 3 input file, the user will be prompted to enter the
name of the file. If the filename contains spaces or the pathname contains spaces, the pathname
should be entered in quotations. If the surface characteristics are in a file that is not an
AERSURFACE file or AERMET stage 3 input file, the format should follow that as outlined in
the AERMET User’s Guide, Section 4.7.7 (U.S. EPA, 2021b). After entering the filename,
AERSCREEN will check for its existence and if it does not exist, the user will be re-prompted
for the filename. AERSCREEN will also check the file for format and valid values for surface
characteristics and if the format is incorrect or surface characteristics are not valid, the user will
be re-prompted for the surface characteristics type (user, AERMET tables, or external file) when
entering data from the prompts. If the data is entered from AERSCREEN.INP and the file is
missing, the format is incorrect or surface characteristics are not valid, AERSCREEN will alert
the user and stop processing.

AERSCREEN will also alert the user if the ambient temperatures exceed current world record
temperatures (183 K and 331 K), Bowen ratio is less than -10 or greater than 10, and if the
surface roughness is less than 0.001 (but positive) or greater than two meters. If surface
roughness is less than 0.001 and not negative, AERSCREEN automatically resets the value to
0.001 and notifies the user. In the case of these warnings, AERSCREEN will use the entered
values but warns the user that they may exceed reasonable values.

If the user uses the AERSCREEN input file to enter the meteorological parameters, the inputs are
as follows in the third block of data of the input file and the data section is denoted by “**
MAKEMET DATA” in the input file. The order of the MAKEMET data line relative to the
other data sections is unimportant. In the AERSCREEN.INP file, temperatures are in degrees
Kelvin. For prompts based input, temperatures are in degrees Fahrenheit or Kelvin. Regardless
of the units convention, wind speeds are in m/s and anemometer height is in meters. The
AERSCREEN.INP and prompts inputs are shown in Figure 12.




                                                  22
                                             AERSCREEN.INP meteorological inputs
** MAKEMET DATA          MinT       MaxT Speed         AnemHt Surf Clim   Albedo    Bowen   Length   SC FILE
**                     250.00     310.00   0.5         10.000    0    0   0.1600   0.8700   0.0440   “aersurface_12.out”

** ADJUST U*             Y
                                                           Prompts inputs
Enter Min & Max Ambient Temperatures (K) or
<Enter> to default to 250 310 K...

Enter Minimum Temperature (K):

If user enters a number for minimum temperature:

Enter Maximum Temperature (K):

Enter Minimum Wind Speed or <Enter> to default to 0.5 m/s...

Enter Anemometer Height or <Enter> to default to 10.0 meters...

--------------------------------
 1) Single user specified values
 2) AERMET seasonal tables
 3) External file
 --------------------------------
  Enter surface characteristics option:

If the user enters 1

Enter Albedo:

Enter Bowen Ratio:

Enter Surface Roughness Length (m):

If the user enters 2
1) Water
2) Deciduous Forest
3) Coniferous Forest
4) Swamp
5) Cultivated Land
6) Grassland
7) Urban
8) Desert Shrubland

Enter Dominant Surface Profile:

1) Average Moisture
2) Wet Conditions
3) Dry Conditions

Enter Dominant Climate Profile:

If user enters 3

Enter filename containing surface characteristics.
Enclose filename with quotes if path or filename includes spaces...

Enter Y or y to adjust u* or N or n to not adjust u*
  Figure 12. AERSCREEN.INP and prompts inputs for meteorological and surface
  characteristics data.
                                       23
The parameters in the input file are:
   • Minimum temperature
   • Maximum temperature
   • Minimum wind speed
   • Anemometer height
   • Land use type for surface characteristics
          o 0 = user-entered surface characteristics
          o 1 = water
          o 2 = deciduous forest
          o 3 = coniferous forest
          o 4 = swamp
          o 5 = cultivated land
          o 6 = grassland
          o 7 = urban
          o 8 = desert shrub land
          o 9 = use external file of surface characteristics
   • Climatology type ( for land use of 1 through 8)
          o 1 = average moisture
          o 2 = wet conditions
          o 3 = dry conditions
   • User defined albedo (not used/requested if land use type is 1 through 9)
   • User defined Bowen ratio (not used/requested if land use type is 1 through 9)
   • User defined surface roughness (not used/requested if land use type is 1 through 9)
   • External surface characteristics filename (not used/requested if land use type is 0 through
       8)
   • Option to adjust or not adjust surface friction velocity u*

When determining surface characteristics, the user should consider the location of the source
(stack or center of volume or area source). Often in emission inventories, the location given for
a source is not the actual location of the source, but an average of sources in a facility or location
of an address. The user should verify coordinates of a stack, volume, or area source. The exact
location of the source is important in determining surface characteristics, especially when using a
tool such as AERSURFACE. Inaccurate source locations can lead to inaccurate surface
characteristics estimations, especially surface roughness. When determining surface
characteristics for the source, regardless of method (user-entered, AERMET tables, or
AERSURFACE), the user is highly encouraged to review Section 3.1 of the AERMOD
Implementation Guide (U.S. EPA, 2021c) and if using AERSURFACE, to review the
AERSURFACE User’s Guide (U.S. EPA, 2020).




                                                 24
2.4 Terrain


   For terrain processing in AERMAP, the user enters the following:

   •   Include terrain processing (yes=include terrain, no=do not include terrain effects)
   •   Probe distance (meters)
   •   Include discrete receptor distances (discussed in Section 2.6) (beginning with version
       11060)
   •   Flagpole receptors (discussed in Section 2.7)
   •   Source elevation or use AERMAP to determine source elevation
   •   Source coordinates (geographic or UTM)
   •   NAD datum (NAD 27 or 83)
   •   UTM zone (if UTM coordinates entered)

If the user is processing a rectangular area source, the only inputs the user enters via the prompts
are probe distance, use of discrete receptor distances (version 11060), flagpole receptors, and
source elevation. The user will not have the choice of using AERMAP for source elevation
determination. If flat terrain is being processed for any source type, the user cannot use
AERMAP for source elevation determination. When entering data via the prompts and
processing terrain, the user has the choice of inputting geographic coordinates (latitude and
longitude) or UTM coordinates, as well as the NAD datum of the coordinates , North American
Datum of 1927 (NAD 27) or North American Datum of 1983 (NAD 83). If the user enters
geographic or UTM coordinates with NAD 27 datum, AERSCREEN converts the coordinates to
UTM coordinates with NAD 83 datum. If the user enters geographic coordinates with NAD 83,
AERSCREEN converts the coordinates to UTM coordinates with NAD 83 datum and writes
those to the AERSCREEN.INP file. If the terrain files read in AERMAP are NAD datum 27 and
not datum 83, AERMAP will do the necessary conversions to NAD 27 for terrain processing in
AERMAP. For more information about the NAD conversion process see the AERMAP User’s
Guide (U.S. EPA, 2018).

If geographic to UTM conversion is performed, AERSCREEN will write the converted NAD 83
UTM coordinates to the new AERSCREEN.INP file with a message that the latitude and
longitude coordinates were converted to UTM coordinates. AERSCREEN will also write a
message to the input file if coordinates were switched from NAD 1927 to NAD 1983. When
entering data using the AERSCREEN.INP file, coordinates must be in UTM coordinates. If the
coordinates are indicated to be in NAD 1927, AERSCREEN will convert to NAD 1983 UTM
coordinates and notify the user. Coordinates should only be in NAD 1927 if the user manually
changed the coordinates and NAD in AERSCREEN.INP. The variables are as follows in the
fourth line of the AERSCREEN input file (Figure 13). Terrain data is denoted by the term “**
TERRAIN DATA” in the input file. Prompts are also shown in Figure 13.




                                                25
                                                      AERSCREEN.INP inputs
** TERRAIN DATA           Terrain        UTM East        UTM North       Zone    Nada   Probe   PROFBASE   Use AERMAP elev
**                           N           406672.0        3698970.8         12       1     5.0      18.30          N

                                                              Prompts inputs
Include Terrain Heights? (y/n):

If user enters “y” or “Y”:

Enter Maximum Distance (m) to probe
<Enter> for default (10000 m):

If user enters “n” or “N”:
Enter Maximum Distance (m) to probe
 <Enter> for default (5000 m):

Enter stack elevation (m) or
<Enter> for AERMAP derived elevation:

If the user enters “n” or “N” for terrain or source is a rectangular area source:

Enter source elevation (m) or
<Enter> for default 0 m:

If user enters “y” or “Y” for terrain:

Enter coordinate type:
LATLON for latitutde & longitude or
UTM for UTM coordinates

If the user enters LATLON:

Enter Source Latitude (North positive) (xx.xxxx):

Enter Source Longitude (West negaitive) (xxx.xxxx):

If the user enters UTM:

Enter Source UTM Easting (xxxxxx.x):

Enter Source UTM Northing (xxxxxxx.x):

The following prompt is shown for UTM coordinates:

Enter Source UTM Zone (xx):

------------------------------------------------------------------------------
Option (1) - North American Datum of 1927
Option (4) - North American Datum of 1983
-----------------------------------------------------------------------------

Enter Option for Applicable UTM Nada:
   Figure 13. AERSCREEN.INP and prompts inputs for terrain data.
                                                                        26
Input parameters in AERSCREEN.INP are:

   •   Terrain flag (Y=use terrain, N=do not use terrain)
   •   UTM X coordinate
   •   UTM Y coordinate
   •   UTM zone
   •   NAD datum of source location
   •   Probe distance in meters
   •   Source elevation (feet or meters)
   •   Override source elevation with AERMAP value (Y=yes, N=no)

When the probe distance is entered, AERSCREEN checks to see if the probe distance is a
multiple of 25 meters. If the distance is not a multiple of 25, the probe distance is reset to the
next distance that is greater than the entered probe distance and is a multiple of 25.
AERSCREEN alerts the user of the change. For example, if the entered probe distance is 1,031
m, AERSCREEN will reset the distance to 1,050 m. This is done because the receptor spacing
between zero and 5 km is 25 m and a multiple of 100 between 5 km and the probe distance. The
reset makes it easier to perform the calculations.

If the user enters the source coordinates as latitude and longitude, the UTM zone will not be
requested and is determined by AERSCREEN. If not processing terrain, the user can enter the
actual elevation for the source or choose a default of zero. The user will not be prompted for
AERMAP override of user-entered source elevation.

When entering data via the prompts, the prompt for terrain processing and overriding of source
elevation with AERMAP will appear for all source types except rectangular area sources. The
other prompts will appear for all sources.

The name(s) of the terrain input file(s) that AERMAP reads are input into AERSCREEN by a
file called demlist.txt, which is to be located in the same directory as the AERSCREEN
executable or local folder in which the user is working. The demlist.txt file is not created by
AERSCREEN but the user must create the file prior to running AERSCREEN. If terrain is to be
processed, AERSCREEN will check for the existence of this file and if it is not present,
AERSCREEN will stop processing. The general format of the file and three examples are shown
in Figure 14. The general format is that the first line contains either “NED” or “DEM” (the case
can be lower or upper case) as the first three characters to denote the file type. The rest of the
line is for informational purposes and not read by AERSCREEN. The second line is a delineator
between the file type and the file list, usually a series of dashes. The third line is to specify the
location of the grid files (conus.las, conus.los, etc.) that will be used for NAD conversion (from
27 to 83 or vice versa). The location is specified by starting the line with “NADGRIDS”
followed by the pathname of the files. If the pathname contains spaces, the entire pathname
should be enclosed in quotations. Beginning with AERSCREEN version 11060, a trailing “\” is
no longer necessary at the end of the pathname. In Figure 14a, AERSCREEN will accept

                                                 27
“c:\grid files\” or “c:\grid files”. If the files are in the current working directory1, the rest of the
line after “NADGRIDS” can be the full path of the current working directory, blank, or .\,.
However, if the files are not in the working directory, AERSCREEN will stop processing.
Regardless of the NAD datum of the coordinates, the field will be read by AERSCREEN and
input into AERMAP. If the line beginning with NADGRIDS is not in the demlist.txt file,
AERSCREEN will notify the user and stop processing.

Finally beginning with the fourth line, is the list of the files to be read into AERMAP, each file
on a separate line. If the filename or pathname of the file contains spaces, the filename or
pathname must be enclosed in quotations. For NED files only, the units of the terrain data can be
included. The units are:

    •   FEET for units of feet
    •   DECI-FEET or DECIFEET for units of decifeet
    •   DECA-FEET or DECAFEET for units of decafeet
    •   METERS for meters
    •   DECI-METERS or DECIMETERS for units of decimeters
    •   DECA-METERS or DECAMETERS for units of decameters

Note that the units are not case sensitive, so lower-case text is allowed. If no units are entered,
i.e. blank after the filename, the units are understood to be meters and AERMAP will give a non-
fatal warning to the user when AERMAP is executed. If units are included, when AERSCREEN
creates the AERMAP.INP file, the TIFFDEBUG keyword will be added to the DATAFILE line
in the AERMAP.INP file.

In Figure 14a, a single National Elevation Data (NED) file called ned_file.tif is to be read into
AERMAP with units of meters by default. Also, the NADGRIDS files are located in a folder
with spaces in the pathname so the filename is in quotations. Figure 14b gives an example of a
NED file whose pathname contains spaces, so the name is enclosed in quotations. The units of
the terrain are specified to be meters. Figure 14b also shows that the location of the grid files
used for NAD conversion. Figure 14c shows a list of DEM files that will be processed in
AERMAP with NAD grid files located in the current working directory. Note that units cannot
be included with DEM files.

Users are encouraged to use NED data as DEM data is static and no longer updated. NED data is
more up to date and is regularly updated.




1
  Current working directory refers to the directory or folder that a DOS prompt is working in when using a DOS
window or to the folder that the AERSCREEN executable is in when double clicking the AERSCREEN executable
icon.
                                                      28
Figure 14. Example formats of demlist.txt.


If terrain is to be included, users should consult the AERMOD Implementation Guide,
specifically sections 4.3, 4.4, and 4.5 (U.S. EPA, 2021c) as well as the AERMAP User’s Guide
and addendum (U.S. EPA, 2018).


2.6 Inclusion of discrete distances


Beginning with version 11060, AERSCREEN allows for the input of up to ten discrete receptor
distances that are not part of the regularly spaced receptor network created by AERSCREEN
(See Section 3.4). These could include distances to specific locations near a source such as a
monitor, school, residential area, etc. AERSCREEN will read all of the locations input by the
user but will only process receptors that are between the ambient distance and probe distance.
Discrete receptor use is entered in AERSCREEN.INP via the 6th data line in AERSCREEN.INP
(Figure 15) or during the terrain processing prompts when entering via the prompts. If the user
wishes to include discrete distances, the distances should be entered into a simple text file. The
user will also be prompted for the filename of distances. The distances listed in the file can be in

                                                29
several units: meters, feet, kilometers, or miles and is independent of whether other data (source
inputs, meteorology, etc.) are in metric or English units. To define the units, the first line of the
text file should be the line “units: “followed by the units of the distances. An example file is
shown in Figure 16 with distances listed in meters. The format of the units line is not case
sensitive but it must be the first line of the file. Distances can be entered as:
    • FEET or FT for feet
    • METERS for meters
    • KILOMETERS, KILO-METERS, or KM for kilometers
    • MILES for miles

If the units line is present but no distance units are entered, i.e. the line is just “units: “, then
AERSCREEN will assume distance units of meters. When entering the filename from
AERSCREEN.INP, if the file does not exist, or the number of receptors exceeds ten, or no units
line is listed, AERSCREEN will alert the user and stop processing. If entering the filename
using prompts and one of the conditions above is met, AERSCREEN will alert the user and re-
prompt for a filename.

If the discrete receptor data line is not in AERSCREEN.INP, AERSCREEN will assume no
discrete receptor distances will be used in modeling. The user can then include discrete receptor
use in the data validation phase of AERSCREEN.

                                          AERSCREEN.INP inputs
  ** DISCRETE RECEPTORS        Discflag    Receptor file
  **                            Y         "discrete_rec.txt"
                                                Prompts inputs
  Include up to 10 discrete receptors (y/n)?

  If user enters “y” or “Y”:

  Enter name of file with discrete receptors.
  Enclose filename with quotes if path or filename includes spaces...
Figure 15. AERSCREEN.INP and prompts inputs for including discrete distances.


 units: meters
 26.0
 35.1
 111.5
 427.35
 535.0
Figure 16. Sample distances in a discrete distances text file.




                                                        30
2.7 Other inputs


Other inputs or options used by AERSCREEN are:

   •    units of inputs (metric or English),
   •    urban/rural classification
   •    urban population if urban
   •    minimum ambient distance (feet or meters)
   •    use of flagpole receptors
   •    flagpole receptor height (feet or meters)

These variables in the sixth line of the AERSCREEN input file are shown in Figure 15 and are
denoted by the term “** UNITS/POPULATION.” This line must be listed after the source input
line. While entering data via prompts, the English or metrics unit prompt is before any other
prompts, while the urban/rural and ambient distance prompts occur during the source input
processing. The flagpole receptor prompts occur in the terrain inputs processing.

                                             AERSCREEN.INP inputs
  ** UNITS/POPULATION          Units   R/U    Population        Amb. dist.   Flagpole   Flagpole height
  **                             M     R              0.            50.000       N        0.00
                                                 Prompts inputs
  English or Metric Units? (E or M):

  Rural or Urban? (R or U):

  Enter Population of Urban Area:

  Enter Minimum Distance (meters) to Ambient Air –
  <Enter> for default (1 m):

  Use Flagpole receptors? (y or n):

  If user enters “y” or “Y”:

  Enter Flagpole receptor height (meters)
Figure 17. AERSCREEN.INP and prompts inputs for other inputs.




                                                           31
Inputs in AERSCREEN.INP are:
   • Units of data (M=metric, E=English)
   • Urban/rural flag (U=urban, R=Rural)
   • Population for urban source
   • Minimum ambient distance
   • Use Flagpole receptors
   • Flagpole receptor height (ignored if flagpole receptors = no)

If the units flag in AERSCREEN.INP is set to “E” AERSCREEN will stop processing and notify
the user that the flag is not set to “M.” for metric. The user can enter the data in English units
when entering data from the prompts but AERSCREEN will change the units flag to metric and
convert the variables from English to metric units during processing. When AERSCREEN
creates the AERSCREEN.INP file from prompt-entered data, there will be a comment in the new
input file that units were converted from English to metric.

For minimum ambient air distances for non-volume sources, when entering data with English
units, the default value listed will be 3.3 feet, or 1 meter. For volume sources, the ambient
distance must be greater than or equal to 2.15 times the initial lateral dimension, 2.15σy plus one
meter. In AERMOD, receptors with source-receptor distances less than 2.15σy plus one meter
are not included in concentration calculations. When entering data via the prompts, the default
value that is listed will be 2.15σy plus 1 m (or equivalent in feet). If the user chooses the default
value by hitting <Enter>, that will be the ambient distance. If the user enters a different value
from the listed default value, it must be greater than or equal to the default value listed.
Otherwise, the user will receive a message that the value reset to 2.15σy plus 1 m. When
obtaining the ambient distance from AERSCREEN.INP, AERSCREEN will compare that value
against 2.15σy plus 1 m and if the entered value is less than 2.15σy plus 1m, it is reset to 2.15σy
plus 1 m. If the user does not wish to use the reset value, it change be changed at the validation
page but must be greater than or equal to 2.15σy plus 1m.

When the source is a non-volume source and the ambient distance is less than 1 meter in the
AERSCREEN.INP, the distance will be reset to 1 meter and AERSCREEN will alert the user. If
the user enters a distance less than 1 meter using the prompts, the distance will be reset to 1 m
and the user will be alerted.


2.8 Fumigation options

Beginning with version 15181, AERSCREEN will calculate fumigation due to inversion break-
up and coastal fumigation for point sources with release heights (above ground level) 10 m or
more in height. The fumigation equations are taken from SCREEN3 (U.S. EPA, 1995) and
follow the methodology of Turner (1970). The inputs to AERSCREEN.INP are:

   •   Calculate inversion break-up fumigation (Y=calculate fumigation, N=do not calculate
       fumigation)
   •   Calculate shoreline fumigation (Y=calculate fumigation, N=do not calculate fumigation)
                                                 32
   •    Minimum distance to shoreline in meters (less than 3,000 m)
   •    Optional direction to shoreline from source (0-360 degrees or -9 for no specified
        direction)

For shoreline fumigation, the user also enters the minimum distance to the shoreline from the
source and the user has the option to specify the direction from the source to the shoreline when
using spatially varying surface characteristics for MAKEMET. This option allows AERSCREEN
to use appropriate surface characteristics corresponding to the upwind direction from the source
to shoreline. For the fumigation options, the source is considered rural, no downwash effects are
included, and no terrain effects are included. For shoreline fumigation, if the distance for a
concentration is less than 200 m, the concentration is set to zero. Likewise, for inversion break-
up fumigation, if the distance for a concentration is less than 2,000 m, the concentration is set to
zero. The inputs for fumigation are shown in Figure 18.

                                          AERSCREEN.INP inputs
  ** FUMIGATION                  Inversion Break-up             Shoreline        Distance          Direct     Run
  AERSCREEN
  ** FUMIGATION                   Inversion Break-up Shoreline                   Distance          Direct     Run
                                              AERSCREEN
  **                                    N                 N                            0.00           0.0       Y
                                                 Prompts inputs
  Apply inversion break-up fumigation (y/n):

  Apply shoreline fumigation (y/n):

  Enter minimum distance to shoreline (m):

  Enter optional direction to shoreline (0 - 360 degrees) or enter -9 or <Enter> for no specific direction:

  Run AERSCREEN (y/n):

Figure 18. AERSCREEN.inp and prompt inputs for fumigation.




                                                         33
2.9 Optional debug file


Beginning with version 15181, AERSCREEN allows for the option to output a debug file that
contains all intermediate output from the stages of AERSCREEN (PROBE and FLOWSECTOR)
described in Section 3.5 and 3.6 of this guide. When fumigation options are selected, the debug
option will also output the meteorological variables and iterations of the fumigation calculations.
The inputs for the debug option are shown in Figure 19.

                                         AERSCREEN.INP inputs
  ** DEBUG OPTION         Debug
  **                        N
                                               Prompts inputs
  Enter Y or y to turn on the debug option or <Enter> to not use the debug option

Figure 19. AERSCREEN.inp and prompt inputs for fumigation.


2.10 Non-default name for output file


The default output files for AERSCREEN are AERSCREEN.OUT and max_conc_distance.txt.
The default name for the optional debug file is concentrations.txt and fumigate_debug.txt for
fumigation output. AERSCREEN.OUT lists the inputs and various outputs of the AERSCREEN
run. The file max_conc_distance.txt, lists the maximum concentration by distance. Beginning
with AERSCREEN version 11060, the user can choose different names other than the defaults.
The filename must have an “.out” extension. The user can specify a filename within the current
working folder or a complete path. If a complete pathname is entered, AERSCREEN will check
to make sure that the target folder or directory exists. If the folder does not exist, the user must
re-enter the filename. The filename that is used for output file is also used to construct the
maximum concentration by distance file as well the debug files. The prefix (including folder
name) of the new output file is used for the maximum concentration file and debug files. The
prefix (including folder name) is also used to copy the final AERSCREEN.INP file and
AERSCREEN.LOG files to new files that have the same prefix as the output file. The user can
change the filename using prompts or by the seventh data line beginning with “** OUTPUT
FILE” followed by the output filename. Figure 20 shows the AERSCREEN.INP inputs and
prompts inputs. If the output file option is not listed in AERSCREEN.INP, AERSCREEN will
assume the default AERSCREEN.OUT for the filename and the user can change the filename
during the data validation phase of AERSCREEN.




                                                       34
                                          AERSCREEN.INP inputs
  ** OUTPUT FILE "AERSCREEN.OUT"

                                                Prompts inputs
  Enter name of AERSCREEN output file
  Enter <Enter> to use default name AERSCREEN.OUT
  Filename should include .out or .OUT extension
  If filename contains spaces, enter entire filename in quotations
Figure 20. AERSCREEN.INP and prompts inputs for output filename.


2.11 Error checking


When entering data via the AERSCREEN.INP file or via prompts, AERSCREEN will check for
invalid responses for flags (use downwash, terrain, urban/rural, etc.) and numeric values (stack
height, building height, etc.). When processing input from the AERSCREEN.INP file, any flags
or parameters found to be invalid or outside a realistic data range (minimum ambient temperature
is greater than maximum ambient temperature), AERSCREEN lists error messages for the
parameters to the AERSCREEN.LOG file and stops AERSCREEN processing to allow the user
to correct the values in the AERSCREEN.INP file. Examples would be a character other than
“Y”, “y”, “N”, or “n” for the building downwash flag or a negative building height for
downwash. If processing input data from the prompts, AERSCREEN will re-prompt the user for
a valid response. For the two examples listed above, AERSCREEN would re-prompt the user
for responses. Appendix A lists the input parameters, reasons for invalid values, and actions
taken by AERSCREEN.

When entering data from AERSCREEN.INP, AERSCREEN checks to make sure that the
emissions data is listed before the building, terrain, and miscellaneous data lines. If the
emissions data line is listed after one of the other three lines, AERSCREEN notifies the user and
stops processing.

AERSCREEN also checks for the presence of several files, if applicable:
  • Demlist.txt (when processing terrain)
  • BPIPPRM input file (if processing downwash and filename is entered)
  • External surface characteristics file (if isurf equals 9)
  • Discrete receptor file (if processing discrete receptors)

If these files are not found, AERSCREEN issues a message and stops processing. Note that if
demlist.txt does not exist, AERSCREEN stops processing, regardless of whether data is being
entered via prompts or AERSCREEN.INP. AERSCREEN will also check if the pathname of the
output file is valid. If the folder or directory does not exist, AERSCREEN issues a message and
stops processing. AERSCREEN also checks for the presence of the AERMOD and MAKEMET
executables in the current working folder. If one of those executables is not present,
AERSCREEN issues a warning and prompts the user for the location of the executable.
AERSCREEN will copy the executable from the entered locations to the current working folder.
                                                        35
If processing downwash, AERSCREEN will check for the presence of the BPIPPRM executable
and the AERMAP executable if processing terrain. If those are not present, AERSCREEN will
issue a warning, prompt the user for the locations of the executables, and copy them to the
current working folder.




                                            36
3. AERSCREEN Program Execution

The AERSCREEN program can be run from the command-prompt or by double-clicking on the
AERSCREEN.EXE from Windows Explorer. The user should make sure that demlist.txt, the
AERMOD, MAKEMET, and if necessary the AERMAP and BPIPPRM executables are in the
current working directory. General AERSCREEN processing is shown in Figure 21. If a restart
file generated from a previous run (called ‘AERSCREEN.INP’) is present in the folder, then the
user will be asked to continue with the restart file or enter data via the prompts (Figure 22a). If
there is no restart file, the prompts will begin automatically (Figure 22b).




Figure 21. AERSCREEN processing and stages.




                                                37
Figure 22. AERSCREEN start screen.


3.1 Data input and validation


If the user chooses the restart file, AERSCREEN goes directly into the user validation page. The
user should carefully review the data to ensure accurate inputs. If processing terrain, particular
attention should be paid to the coordinates to ensure that any NAD conversions were successful.
Also on the validation page, the user will have the option of rerunning the same inputs or
selectively modifying specific components, such as building or terrain information (Figure 23).
For example, if changes are to be made to building parameters, the user chooses option 2 and a
list of further options will appear (Figure 25). The user can change individual parameters
without having to re-enter all the parameters. The option to re-enter all parameters is a choice as
well. Changes to individual parameters are available for source, meteorological, and terrain
parameters as well. Some options cannot be changed without changing another parameter first.
These include changing urban population for a rural source or surface characteristics (i.e. user
defined values when AERMET tables are chosen). Figure 24 shows the list of choices for
various source types, Figure 25 shows the choices for building parameters, Figure 26 lists the
choices for terrain processing, Figure 27 lists the choices for meteorological processing and
Figure 28 lists the fumigation options. For each submenu, once the desired changes are made,
                                                38
the user can hit <Enter> to return to the validation page. Some changes will automatically return
the user to the validation page, such as choosing option 1 in Figure 25a for building downwash
or turning the debug option on or off.

Note, that if the user chooses to change source data, the source type cannot be changed; only
parameters for the source type from the AERSCREEN.INP file or from the prompts. For
example, the user cannot change the source from point to rectangular area. For building data, if
the user is running AERSCREEN for an area source, rectangular or circular, or a volume source
(which do not use building downwash) and chooses option 2 from the validation page,
AERSCREEN will give the message that building parameters cannot be changed due to source
type and return to the validation page. The same is true for changing terrain data when running a
rectangular area source. The user may also change parameters in the AERSCREEN.INP file
before running AERSCREEN, instead of modifying the data using the prompts.




                                               39
                               AERSCREEN 16216

        ----------------- DATA ENTRY VALIDATION -----------------
                       METRIC             ENGLISH
 ** STACKDATA ** ---------------    ----------------

 Emission Rate:       1.0000 g/s                   7.937 lb/hr
 Stack Height:         61.00 meters               200.13 feet
 Stack Diameter:       5.000 meters               196.85 inches
 Stack Temperature:    415.0 K                     287.3 Deg F
 Exit Velocity:       11.000 m/s                   36.09 ft/s
 Stack Flow Rate:     457646 ACFM
 Model Mode:           RURAL
 Dist to Ambient Air:          50.0 meters                       164. feet


 ** BUILDING DATA **

 User defined BPIPPRM input file:
 BUILDING.INP




 ** TERRAIN DATA **

 No Terrain Elevations
 Source Base Elevation:     25.0 meters          82.0     feet

 Probe distance:   10000. meters            32808. feet

 No flagpole receptors

 Using discrete receptors in
 discrete_rec.txt

 Only receptors between the ambient and probe distances will be included
 Input distance units are: METERS


 ** FUMIGATION DATA **

 No fumigation requested


 ** METEOROLOGY DATA **

 Min/Max Temperature:     270.0 / 310.0 K       26.3 /       98.3 Deg F

 Minimum Wind Speed:       0.5 m/s

 Anemometer Height:      10.000 meters

 Using surface characteristics in file:
 season_3.out

 Surface friction velocity (u*): adjusted

DEBUG OPTION OFF



 AERSCREEN output file:
 AERSCREEN_FLAT_DW.OUT


 *** AERSCREEN Run is Ready to Begin - Choose Option to Proceed ***

                        1 - Change Source Data;
                        2 - Change Building Data;
                        3 - Change Terrain Data;
                        4 - Change Meteorology Data;
                        5 - Change Fumigation Data;
                        6 - Change Title;
                        7 - Change Debug Option;
                        8 - Change Output Filename;
                        9 - Stop AERSCREEN;
                                  - or -
                         Hit <Enter> to Start Run


Figure 23. AERSCREEN validation page.




                                                                         40
Figure 24. Submenus for changing source parameters for a) point, capped or horizontal
stack, b) volume, c) rectangular area, d) circular area, and e) flare sources.




                                          41
Figure 25. Building downwash submenus for a) building downwash included and b)
building downwash not included.




                                         42
Figure 26. Terrain submenus for a) terrain heights included, b) terrain heights not
included and c) rectangular area sources.




                                            43
Figure 27. Meteorological data submenu for a) when not adjusting u* and b) when
adjusted u* is being used.




Figure 28. Fumigation submenus for various fumigation options.

If the user chooses to run from the restart file, while reading the file, AERSCREEN may
automatically change some of the options in the file, depending on other options. If the source
being modeled is a rectangular area source and the terrain flag is set to “y” or “Y” then the
terrain flag is reset to “N.” For rectangular area sources, circular area sources, or volume
sources, if the BPIP flag is set to “Y” or “y” in the input file then the BPIP flag is set to “N” and
no downwash is calculated. If the user enters data using prompts instead of the
AERSCREEN.INP file, the validation page will appear after all prompts have been processed for
the source, building, terrain, and meteorological data.


                                                 44
3.2 Meteorological data files


After reading the input file or prompt inputs, and prompting the user for any changes,
AERSCREEN processes the surface characteristics and runs MAKEMET to create the
AERMOD meteorological input files (.sfc, and .pfl files). MAKEMET is run for each temporal
period /spatial sector combination of surface characteristics. Depending on the temporal
resolution and number of spatial sectors of the surface characteristics, one surface and one
profile file (annual, 1 sector) to a maximum of 144 (monthly, 12 sector) surface files and 144
profile files are created, one for each temporal period/spatial sector combination (Figure 29). In
the meteorological files naming convention, the first set of 2-digit numbers refers to the temporal
period of the surface characteristics, which ranges from 1 to 12. If processing annual surface
characteristics, the number would be “01” and if processing seasonal or monthly surface
characteristics, the number would be range from “01” to “04” for seasonal output and “01” to
“12” for monthly output. The second set of numbers in the filenames is the number of spatial
sectors for surface roughness. This can range from “01” to “12” for one sector to 12 sectors.
In Figure 26, aerscreen_01_01.sfc and aerscreen_01_01.pfl use surface characteristics for
January, sector 1; aerscreen_01_02.sfc and aerscreen_01_02.pfl use surface characteristics for
January, sector 2 and so on with aerscreen_12_12.sfc and aerscreen_12_12.pfl using surface
characteristics for December, and sector 12.


 Creating met files aerscreen_01_01.sfc & aerscreen_01_01.pfl

 Creating met files aerscreen_01_02.sfc & aerscreen_01_02.pfl

 Creating met files aerscreen_01_03.sfc & aerscreen_01_03.pfl

 Creating met files aerscreen_01_04.sfc & aerscreen_01_04.pfl

 Creating met files aerscreen_01_05.sfc & aerscreen_01_05.pfl
 .
 .
 .
 Creating met files aerscreen_12_12.sfc & aerscreen_12_12.pfl
Figure 29. Meteorological file creation for monthly 12 sector AERSURFACE output.

The input parameters to MAKEMET, which are normally entered using prompts, are written to a
text file called prompts.inp by AERSCREEN and then “piped” to the MAKEMET call by
AERSCREEN with the call system command, “makemet < prompts.inp.” Using the
MAKEMET prompts shown in Figure 1 as a guide, AERSCREEN assigns the names for the
surface and upper air meteorological files requested in the first two prompts shown in Figure 1
based on the file naming convention described above. The minimum wind speed and
anemometer height are assigned the values entered by the user. The number of wind directions
is automatically set to 1 by AERSCREEN and the wind direction is set to 270 degrees. The
minimum and maximum temperatures are assigned the values entered by the user. The albedo,
Bowen ratio and surface roughness length are assigned the values for the particular
                                                45
temporal/spatial combination being processed. The final prompt, “DO YOU WANT TO
GENERATE ANOTHER MET SET THAT WILL BE APPENDED TO CURRENT FILE?
[TYPE EITHER "Y" OR "y" FOR YES; OR HIT "ENTER" TO EXIT]” is set not to generate
another file. An example for monthly, 12 sector AERSURFACE output is shown in Table 1.


Table 1. MAKEMET prompts and example values for the first month and surface
roughness sector and last month and surface roughness sector for monthly 12 sector
AERSURFACE output.
             MAKEMET prompt                     Value (month 1, sector 1)    Value (month 12, sector 12)
 ENTER SFC MET FILE NAME                        aerscreen_01_01.sfc          aerscreen_12_12.sfc
 ENTER PFL MET FILE NAME                        aerscreen_01_01.pfl          aerscreen_12_12.pfl
 ENTER MIN. WS (M/S)                            User input minimum wind      User input minimum wind
                                                speed                        speed
 ENTER ANEM HT (M)                              User input anemometer        User input anemometer
                                                height                       height
 ENTER OPTION TO ADJUST U* (Y=adjust,N=no       User entered option (Y or    User entered option (Y or N)
 adjustment)                                    N)
 ENTER NUMBER OF WIND DIRECTIONS                1                            1
 ENTER WIND DIRECTION                           270                          270
 ENTER MIN AND MAX AMBIENT TEMPS IN             User entered temperatures    User entered temperatures
 KELVIN
 ENTER ALBEDO                                   Albedo for month 1, sector   Albedo for month 12, sector
                                                1                            12
 ENTER BOWEN RATIO                              Bowen ratio for month 1,     Bowen ratio for month 12,
                                                sector 1                     sector 12
 ENTER SURFACE ROUGHNESS LENGTH IN              Surface roughness for        Surface roughness for month
 METERS                                         month 1, sector 1            12, sector 12
 DO YOU WANT TO GENERATE ANOTHER MET            N                            N
 SET THAT WILL BE
 APPENDED TO CURRENT FILE?
 [TYPE EITHER "Y" OR "y" FOR YES; OR HIT
 "ENTER" EXIT]




3.3 BPIPPRM execution


If downwash is to be considered, BPIPPRM inputs are calculated and written to a BPIPPRM
input file or the user entered input file is used. For either method, BPIPPRM is executed to
create the projected building dimensions for input into AERMOD. If a user-entered file is used
and the processing flag (line 2) of the BPIPPRM input file is not a “P” or “p” then BPIPPRM
will abort and AERSCREEN will notify the user and stop processing. Beginning with
AERSCREEN version 11060, AERSCREEN also checks to make sure only one stack is listed in
the BPIPPRM input file. If more than one stack is listed, AERSCREEN will stop processing and
notify the user.



                                             46
3.4 Source elevation calculation


If terrain is being used, AERSCREEN calls AERMAP to get the source location’s elevation.
The source elevation, user-entered or AERMAP calculated, can be used as the source elevation
in the SO pathway of the AERMOD runstream file, AERMOD.INP, and as the station elevation,
keyword PROFBASE in the ME pathway of the AERMOD input file. If the user has chosen to
replace the input source elevation, either from the restart file or via prompts, AERSCREEN will
use the AERMAP elevation as the source location’s elevation. If the user chose to keep the input
elevation, AERSCREEN will calculate a percent difference between the user-entered elevation
and the AERMAP calculated elevation and write the difference to the AERSCREEN log file.


3.4 Receptor network


An array of receptor distances is also created including the minimum ambient distance,
automatically calculated distances (as described in steps 1 and 2 below), and any discrete
receptor distances. The probe distance is set to the user-specified probe distance, or reset probe
distance (as described in Section 2.4). Depending on the probe distance, there may be two
receptor spacing values:
    1. 25 meters from zero to 5 km
    2. From 5 km to the final probe distance, the spacing is the greater of 25 m or a spacing
       calculated by: (probe distance – 5,000 m)/100 where 100 represents 100 receptors

For example, if the user enters a probe distance of 12, 500 m, the receptor spacing from zero to
5,000 m is 25 m and the spacing from 5,000 to 12,500 is 75 m (7,500 m/100).

Receptors located at distances less than the minimum ambient distance, either discrete or
automatically calculated, are not included in the set of receptors. Also, any discrete receptor
distances that exceed the probe distance are not included. Discrete receptors that are also equal
to any distance in the automatic array are not included to avoid duplicate receptors. Receptor
distances are relative to x=0 and y=0. For point, capped stacks, horizontal stacks, and flare
sources, x=0 and y=0 represent the stack or flare location. For volume and circular area sources,
x=0 and y=0 represent the center of the source.

There are three main routines in AERSCREEN: PROBE, FLOWSECTOR and REFINE as
shown in Figure 19. There are two optional fumigation routines FUMIGATE and SHORELINE
used to calculate maximum concentrations due to inversion break-up fumigation and shoreline
fumigation respectively. PROBE is executed when there is no source-receptor direction
dependency (no terrain, no building downwash, and the source is not a rectangular area source).
FLOWSECTOR is executed when there is a source-receptor direction dependency (terrain and/or
building downwash, or source is a rectangular area source). REFINE is executed after PROBE
or FLOWSECTOR. FUMIGATE and SHORELINE are executed, if chosen, after REFINE.


                                                47
Details about each section and the final output of AERSCREEN are described in each of the
following sections.


3.5 PROBE


PROBE executes AERMOD for each combination of temporal periods and spatial sectors. For
example, if user defined surface characteristics are used (annual, 1 spatial sector), AERMOD is
executed once (Figure 30a). If monthly, 12 spatial sector AERSURFACE output is used, then
AERMOD is executed 144 times, 12 months x 12 sectors (Figure 30b).




Figure 30. Sequence of AERMOD runs in PROBE for different surface characteristics
combinations.

AERSCREEN reads the output from AERMOD for each run and the highest concentration and
its distance from the source are stored in arrays that will be used to find the highest overall
concentration in REFINE. AERSCREEN also retains the high first high (H1H) 1-hour
concentration for each receptor. These concentrations are later used in determining the
maximum concentration by downwind distance.




                                               48
3.6 FLOWSECTOR


FLOWSECTOR is executed when there is a source-receptor direction dependency (terrain and/or
building downwash, or rectangular area source).

If terrain is to be used, AERSCREEN checks for the presence of output from a previous
AERMAP run. If there is output available, AERSCREEN checks the following against the same
parameters in the current AERSCREEN run:
     • source location
     • probe distance
     • minimum ambient distance
     • receptor spacing
     • number of receptors
     • NAD datum
     • UTM zone
     • Type (DEM or NED files), number and names of terrain input files
     • If all of the above parameters match between the existing AERMAP output and the
         current AERSCREEN run, AERSCREEN then checks the receptor coordinates in the
         previous AERMAP run to ensure the distances and directions match the receptor spacing
         of the current run and that all 36 radial directions are included. This step is done in case
         the file was changed or corrupted without the user’s knowledge or if different discrete
         receptors are used, but the number of receptors has not changed.

If any of the above parameters differ, AERMAP will be executed to create new receptor
elevations. If all parameters match, the user is prompted to decide to use the elevations from the
previous output, or to run AERMAP to create new elevations. If the older AERMAP output is
for a source type different than the one being processed in the current run, the user may want to
consider re-running AERMAP. AERSCREEN sets the ANCHORXY, x=0 and y=0 to the source
location and receptor locations are relative to this location. For volume and circular area
sources, this represents the center of the source. For point and flare sources, this is the stack
location.

If AERMAP is run in FLOWSECTOR, AERSCREEN will calculate a domain for the receptor
grid to include with the DOMAINXY keyword in the AERMAP.INP file that AERSCREEN
generates to run AERMAP. This will speed up processing, especially if large terrain files are
used. For FLOWSECTOR, the domain is 1.1 times the probe distance.

After running AERMAP for the receptor elevations, AERSCREEN checks the AERMAP.OUT
file for any warnings or errors. If any are found, they are written to the AERSCREEN log file
and AERSCREEN stops processing.



                                                 49
3.6.1 Rectangular area sources


For rectangular area sources, the angle of the diagonal is calculated from the center to the corner
of the rectangle. Next, radials are calculated every five degrees, beginning with 0 degrees up to
the nearest 5 degrees past the diagonal. For example, if the diagonal of the source was found to
be 26 degrees, radials are calculated for 0, 5, 10, 15, 20, 25, and 30 degrees, as shown in Figure
31.




Figure 31. Receptor radials for rectangular area sources.


For each one of these radials, receptors are placed out to the probe distance at the calculated
spacing(s). For each radial, the WDROTATE keyword is used in the ME pathway of the
AERMOD runstream input file with the value set to the angle of the radial (0, 5, 10, etc.). See
Figure 32 for examples.




                                                50
Figure 32. ME pathway in the AERMOD runstream with WRDOTATE keyword and
values for various angles.


The WDROTATE keyword rotates the wind to be along the radial being processed in AERMOD
because the wind direction in the meteorological files is 270 degrees. Receptor x and y
coordinates are also calculated based on the angle of the radial, i.e. for the 10 degree radial at 50
m x=49.24 m, y=8.68 m. AERMOD is run for each of the radials for each surface characteristic
temporal/spatial sector combination. In the example in Figure 28, for annual surface
characteristics for the whole 360 degree sector, AERMOD is executed seven times, once for each
radial. For seasonal surface characteristics for 2 spatial sectors, AERMOD is executed 56 times,
once for each radial for each season and sector. For monthly surface characteristics with the
maximum 12 sectors for surface roughness, AERMOD is executed 1,008 times, once for each
radial, month, and surface roughness sector. Figure 33 shows sample AERMOD run sequences
for seasonal, 12 sector surface characteristics for a rectangular area source with six radials. First,
winter surface characteristics for sector 1 are used for each of the six radials. Next, winter
surface characteristics for sector 2 are used for each of the six radials. This process is followed
for each season and surface characteristic sector finishing with autumn sector 12 surface
characteristics. For each temporal/sector combination, AERSCREEN then determines the worst
case concentration, associated radial, and meteorology to be used later in the REFINE stage.




                                                 51
 Processing Winter

 Processing surface roughness sector 1
 Processing wind flow sector   1
 Processing wind flow sector   2
 Processing wind flow sector   3
 Processing wind flow sector   4
 Processing wind flow sector   5
 Processing wind flow sector   6
 Processing surface roughness sector 2
 Processing wind flow sector   1
 Processing wind flow sector   2
 Processing wind flow sector   3
 Processing wind flow sector   4
 Processing wind flow sector   5
 Processing wind flow sector   6
 .
 .
 Processing surface roughness sector 12
 Processing wind flow sector   1
 Processing wind flow sector   2
 Processing wind flow sector   3
 Processing wind flow sector   4
 Processing wind flow sector   5
 Processing wind flow sector   6
 .
 .
 Processing Autumn
 Processing surface roughness sector 12
 Processing wind flow sector   1
 Processing wind flow sector   2
 Processing wind flow sector   3
 Processing wind flow sector   4
 Processing wind flow sector   5
 Processing wind flow sector   6
Figure 33. AERMOD run sequences for rectangular area source for seasonal 12 sector
surface characteristics.




                                          52
3.6.2 Non-rectangular area sources


For non-rectangular area sources, FLOWSECTOR arranges receptors along 36 radials from the
source, every 10 degrees, shown below in Figure 34. AERMOD is executed for each temporal
period (annual, seasonal, or monthly) of the surface characteristics (Figure 35). However, it is
not executed for each surface roughness sector. Instead, for each radial, AERSCREEN
determines the upwind surface roughness sector of the radial being processed. That is,
AERSCREEN determines the sector that contains the direction 180 degrees from the radial being
processed. That is done because the radial is considered in the direction of the flow while
surface characteristics are for the sector from which the wind is blowing, i.e. upwind. Figure 36
shows which sector is used for the 10 degree flow vector (solid black arrow) for three sectors
from AERSURFACE output. In this case, the upwind direction of 10 degrees, 190 degrees
(dashed black arrow), is contained in the 90 to 225 surface roughness sector.




Figure 34. Receptor placement for point (including capped and horizontal stacks), flare,
volume, or circular area sources in FLOWSECTOR.



                                               53
 Processing Winter

 Processing wind flow sector 10
 Processing wind flow sector 20
 Processing wind flow sector 30
 Processing wind flow sector 40
 .
 .
 Processing wind flow sector 360
 .
 .
 Processing Spring
 Processing wind flow sector 10
 .
 .
 Processing Autumn
 Processing wind flow sector 10
 Processing wind flow sector 20
 Processing wind flow sector 30
 Processing wind flow sector 40
 .
 .
 Processing wind flow sector 360
Figure 35. AERMOD sequence for seasonal 12 sector surface characteristics when
processing terrain and/or building downwash.




Figure 36. Flow vector (solid arrow) of 10 degrees and associated upwind surface
roughness sector for three surface roughness sectors (0 to 90, 90 to 225, 225 to 0).
                                             54
If building downwash is considered, projected building dimensions calculated by BPIPPRM for
the flow direction being modeled are included in the AERMOD run. If terrain is processed,
AERSCREEN will find the appropriate receptors (based on distance and direction) from the
AERMAP output and include the appropriate terrain data in the AERMOD input file.
AERSCREEN also checks to ensure the receptor coordinates match the specified distance and
direction. If they do not, AERSCREEN will issue an error and stop processing. Since
AERSCREEN generates the receptor elevations via AERMAP, this should not happen, unless
the AERMAP output file became corrupted during processing. When extracting the appropriate
receptors, if any receptors have a missing elevation, i.e. -9999.0, AERSCREEN will skip those
receptors and they will not be included in the AERMOD run for that particular direction.
AERSCREEN will notify the user of how many receptors were skipped for the particular
AERMOD run (Figure 37a). If any receptors did have missing elevations, the warning messages
for those receptors will appear in the AERSCREEN.LOG file for the AERMAP quality
assurance check (Figure 37b). AERSCREEN will notify the user of the total number of
receptors skipped for FLOWSECTOR at the end of the AERSCREEN run (Figure 37c). If the
user finds that receptors have been skipped due to missing elevations, the user may want to
check the input terrain files for gaps or other irregularities or reconsider the probe distance, as
this can affect the final maximum 1-hour concentration from AERSCREEN.




                                                55
Figure 37. Receptor skipping notification during FLOWSECTOR run, with notification of
missing elevations in AERMAP, and total number of receptors skipped for
FLOWSECTOR and REFINE.

For each AERMOD run in FLOWSECTOR, the maximum concentration, downwind distance,
and terrain (if applicable) are stored for later use in REFINE. The stored concentrations are
concentrations for each radial and temporal period of the surface characteristics.


3.7 REFINE


REFINE finds the maximum concentration and associated distance and date output from PROBE
or FLOWSECTOR. If output is from PROBE or a rectangular area source from
FLOWSECTOR, REFINE uses the meteorological files for the temporal period and surface
                                              56
roughness sector of the maximum concentration. If output is from FLOWSECTOR for non-
rectangular area sources, REFINE finds the upwind surface characteristic sector of the flow
direction of maximum concentration as in Figure 36. REFINE then uses the meteorological files
for the appropriate temporal and surface characteristics sector. Receptor spacing becomes one,
two, or five meters, depending on maximum concentration distance, to refine the output. For
rectangular area sources, the receptors are placed along the radial associated with the maximum
concentration. Any discrete receptors supplied by the user are not included in the REFINE
AERMOD run. If building downwash is used, building dimensions based on the flow direction
of maximum concentration are used. If terrain is used, REFINE will rerun AERMAP with the
new receptors in the flow direction of the maximum concentration output from FLOWSECTOR.
As in FLOWSECTOR, REFINE will create a domain to be used with the DOMAINXY keyword
in AERMAP. After running AERMAP, REFINE then runs AERMOD using the new receptors
and appropriate meteorological, building and terrain data. As with FLOWSECTOR, if any
receptors have a missing elevation, they will be skipped, and the user will be notified of how
many were skipped (see Figure 37c for example).


3.8 Fumigation

The optional fumigation calculations, inversion break-up and shoreline fumigation are based on
the equations implemented in SCREEN3 (U.S. EPA, 1995). The inversion break-up calculations
are based on procedures described in Turner (1970). Fumigation calculations are only made for
point type sources, including flares, with release heights 10 m or more above ground level.
3.8.1 Selection of meteorological data

Before fumigation calculations are performed, AERSCREEN determines the appropriate hours
to use from the meteorological data created by MAKEMET. For the fumigation calculations, the
fumigations are based on assumptions of F stability and a stack top wind speed of 2.5 m/s (U.S.
EPA, 1995). Also, for the fumigation calculations AERSCREEN assumes the source is a rural
source, ignores building downwash, and ignores terrain effects.

AERSCREEN reads the meteorological data files that are created as described in Section 3.2 of
this document. Using various meteorological variables, AERSCREEN determines a stability
class (A, B, C, D, E, or F) and stack top wind speed. For those hours that meet the criteria of F
stability and stack top wind speed of 2.5 m/s, AERSCREEN calculates an array of variables that
will be needed for the fumigation calculations.

If no hours meet the stability and wind speed criteria, AERCREEN issues a notice that no hours
meeting the criteria and fumigation calculations are not performed. Otherwise, AERSCREEN
proceeds with the calculations.




                                               57
3.8.2 Inversion break-up fumigation

Inversion break-up fumigation in AERSCREEN uses the inversion break-up fumigation
equations from SCREEN3 (U.S. EPA, 1995) which are based on Turner (1970). For the
fumigation calculations, the distance to maximum fumigation is based on an estimate of the time
required for the mixing layer to develop from the top of the stack to the top of the plume is
calculated by:

𝑋𝑚𝑎𝑥 = (𝑢𝜌𝑎 𝑐𝑝 /𝑅)(∆Θ/∆𝑧)(ℎ𝑖 − ℎ𝑠 )⌊(ℎ𝑖 − ℎ𝑠 )/2⌋                                           (3)

where:

Xmax=distance to maximum concentration (m)
u= stack top wind speed (2.5 m/s)
a=ambient air density (1205 g/m3 at 20°C)
cp=specific heat of air at constant pressure (0.24 cal/gK)
R=net rate of sensible heating of an air column by solar radiation (67 cal/m2/s)
∆Θ/∆z=potential temperature gradient (0.035 K/m for F stability)
hi=height of the top of the plume (he + 2σze) where he is the plume centerline height (m)
hs=physical stack height or release height (m)
σze=vertical dispersion parameter incorporating buoyancy induced dispersion (m)

and the maximum concentration is calculated as:

Χ𝑓 = 𝑄/⌊(2𝜋)0.5 𝑢(𝜎𝑦𝑒 + ℎ𝑒 /8)(ℎ𝑒 + 2𝜎𝑧𝑒 )⌋                                                 (4)

where:

f=maximum ground level concentration due to inversion break-up fumigation (g/m3)
Q=emission rate in g/s
u=stack top wind speed (2.5 m/s)
ye=horizontal dispersion parameter incorporating buoyancy induced dispersion (m)

Other parameters are defined as in Equation 3. To calculate Xmax, AERSCREEN uses an
iterative approach to solve Equation 3, beginning with an initial value of 5,000 m. This iteration
is done for each hour of appropriate meteorology. Once Xmax is found, f is calculate for the
hour using Equation 4. After all hours have been processed, the highest value of f is the
maximum ground level concentration. If the distance to the maximum concentration is less than
2 km, AERSCREEN resets the concentration to zero, consistent with SCREEN3.


3.8.3 Shoreline fumigation

AERSCREEN will calculate shoreline fumigation for sources within 3 km of the coastline.
Again, AERSCREEN incorporates the calculations from SCREEN (U.S. EPA 1995). The
                                                58
assumptions in the calculations are described in Section 3.8.1 above, F stability and onshore flow
of 2.5 m/s at stack top. The maximum ground-level shoreline fumigation concentration is
assumed to occur where the top of the stable plume intersects the top of the well-mixed thermal
internal boundary layer (TIBL). The TIBL height for rural flat terrain as a function of inland
distance can be estimated by:

ℎ𝑇 = 𝐴𝑥 0.5                                                                                (5)

where:
hT=TIBL height (m)
A= TIBL factor containing physics needed for TIBL parameterization (including heat flux)
(m1/2) set to 6 (U.S. EPA, 1995).
x=inland distance (m)

As with the inversion break-up fumigation, the distance to the maximum concentration due to
shoreline fumigation is an iterative process for each hour. The distance, Xmax is found by:
𝑋𝑚𝑎𝑥 = ⌊(ℎ𝑒 + 2𝜎𝑧𝑒 )/6⌋2 − 𝑥𝑠                                                              (6)

Where xs is the shoreline distance and all other variables are defined as in Section 3.8.2. The
maximum concentration at Xf is found by:

Χ𝑓 = 𝑄/⌊(2𝜋)0.5 𝑢(𝜎𝑦𝑒 + ℎ𝑒 /8)(ℎ𝑒 + 2𝜎𝑧𝑒 )⌋                                                (7)

Where
f=maximum ground level concentration due to shoreline break-up fumigation (g/m3) and all
other variables defined as above.

Before proceeding with the shoreline fumigation calculations, AERSCREEN determines if any
of the meteorological hours determined in Section 3.8.1 or hours that match upwind surface
characteristics from the shoreline have a plume height above the TIBL height by calculating the
distance at which the effective stack height is equal to the TIBL height and taking the difference
with the shoreline distance to calculate x0:

𝑥0 = (ℎ𝑒 /6)2 − 𝑥𝑠                                                                         (8)

If x0 is less than zero for all relevant hours then the plume is considered to be below the TIBL
height for the shoreline distance xs and no shoreline fumigation calculations will be performed at
all. If x0 is greater than zero for any relevant hour then shoreline fumigation calculations will
proceed.

As with inversion break-up fumigation, to calculate Xmax for shoreline fumigation AERSCREEN
uses an iterative approach to solve Equation 6, beginning with an initial value of equal to x0
(Equation 8) that is calculated for the particular hour being processed. This iteration is done for
each hour of appropriate meteorology. Once Xmax is found, f is calculate for the hour using
Equation 7. After all hours have been processed, the highest value of f is the maximum ground
                                                59
level concentration for shoreline fumigation. If the distance to the maximum concentration is
less than 200 m, the concentration is set to zero.


3.8.4 AERSCREEN run option

Beginning with version 15181, when the interest is only in the fumigation concentrations,
AERSCREEN allows the option of skipping the screening modeling portion of AERSCREEN
(PROBE, FLOWSECTOR, and REFINE) to save processing time.
3.9 Outputs


AERSCREEN creates the file AERSCREEN.OUT or user-supplied output filename which
contains the following: source information, output from either PROBE or FLOWSECTOR,
meteorology associated with the maximum concentration output from PROBE or
FLOWSECTOR, maximum concentrations by distance, REFINE output (final maximum
concentration and maximum concentration at the minimum ambient distance), and optional
fumigation results. See Section 4 for example output. AERSCREEN also outputs a file called
max_conc_distance.txt, or name based on the user-supplied output filename, that contains the
highest concentration by distance, independent of worst case meteorology and flow direction,
with associated meteorology for the concentrations. These concentrations were calculated in
PROBE or FLOWSECTOR. Also included in the file is the overall maximum concentration
output from REFINE. This concentration is denoted by an asterisk in the file. The format of this
file is shown in Table 2. If the optional debug output is chosen a file containing PROBE or
FLOWSECTOR results is created and has a similar format to the max_conc_distance.txt file
with the exception that for AREA sources, the individual diagonal angles are listed. If
fumigation options are chosen along with the debug option, a fumigation debug file will be
created with the intermediate fumigation calculations. AERSCREEN also copies the
AERMOD.INP file from the REFINE AERMOD run to the file AERSCREEN.INP, containing
the inputs to AERSCREEN entered via prompts or a previous AERSCREEN.INP file with any
changes that were made during AERSCREEN processing2. AERSCREEN also copies the
AERSCREEN.INP and AERSCREEN.LOG files to new files with names based on the user-
supplied filename.




2
  If at any time, AERSCREEN aborts during PROBE, FLOWSECTOR, or REFINE, the user may be able to copy
the current AERMOD.INP file to AERSCREEN.INP to avoid re-entering data.
                                                  60
Table 2. Variables listed in max_conc_distance.txt.
    Variable                                      Description
 Concentration Maximum 1-hour screening concentration (µg/m3). A concentration with a
                preceding asterisk is the overall maximum concentration.
 Distance       Distance (m) from source of maximum 1-hour concentration
 Elevation      Elevation (m) of maximum 1-hour concentration
 Flow           Flow vector (degrees) associated with maximum 1-hour concentration
 Season/Month Season/Month of maximum 1-hour concentration (can be annual, season, or
                month)
 Zo sector      Surface roughness sector number of maximum 1-hour concentration
 Date           Date of maximum 1-hour concentration
 H0             Heat flux (W/m2)of hour of maximum 1-hour concentration
 U*             Friction velocity (m/s) of hour of maximum 1-hour concentration
 W*             Convective velocity (m/s) of hour of maximum 1-hour concentration
 DT/DZ          Lapse rate (K/m) of hour of maximum 1-hour concentration
 ZICNV          Convective mixing height (m) of hour of maximum 1-hour concentration
 ZIMCH          Mechanical mixing height (m) of hour of maximum 1-hour concentration
 M-O LEN        Monin-Obukhov length (m) of hour of maximum 1-hour concentration
 Z0             Surface roughness length (m) of hour of maximum 1-hour concentration
 Bowen          Bowen ratio of hour of maximum 1-hour concentration
 Albedo         Albedo of hour of maximum 1-hour concentration
 REF WS         Wind speed (m/s) of hour of maximum 1-hour concentration
 HT             Anemometer height (m) of hour of maximum 1-hour concentration
 REF TA         Temperature (K) of hour of maximum 1-hour concentration
 HT             Height of Temperature (m) of hour of maximum 1-hour concentration




                                          61
4. Example run


This section will show an example AERSCREEN run for a point source with building downwash
and terrain. Inversion break-up fumigation will also be selected as well as the output of a debug
file. Table 3 gives a summary of the AERSCREEN inputs and Figure 38 shows the
building/stack orientation. Table 4 lists the seasonal surface characteristics and Figure 39 shows
the land use and terrain for the example. Figure 40 lists the inputs for demlist.txt and Figure 41
lists the discrete receptor file contents.

Table 3. Inputs for example AERSCREEN run.
 Parameters           Inputs                                               Input values
 Source               Source type                                          POINT
                      Stack height                                         20 m
                      Emission rate                                        1 g/s
                      Stack diameter                                       0.5 m
                      Stack exit temperature                               300 K
                      Stack exit velocity                                  15 m/s
 Building             Include building downwash                            Yes
                      Building height                                      34 m
                      Maximum horizontal dimension                         120 m
                      Orientation of maximum building dimension to North   90°
                      Minimum horizontal dimension                         60 m
                      Direction of stack from North                        26.6°
                      Distance from stack to building center               67 m
 Meteorology          Minimum temperature                                  261.4
                      Maximum temperature                                  313.1
                      Minimum wind speed                                   1.5 m/s
                      Anemometer height                                    10 m
                      Source of surface characteristics                    AERSURFACE (aersurface_12.out)
                      Adjust u*                                            No
 Terrain              Include terrain                                      Yes
                      Coordinate type                                      Latitude and longitude (LATLON)
                      Source latitude                                      35.891400° N
                      Source longitude                                     78.781940° W
                      NAD                                                  83
                      Probe distance                                       1 km
                      Source elevation                                     126.8
                      Override input elevation with AERMAP derived value   No
 Discrete receptors   Use five discrete receptors, units in meters         discrete_receptors.txt
 Other inputs         Input units                                          Metric
                      Rural/urban                                          Urban
                      Input population                                     2400000
                      Minimum ambient distance                             30 m
                      Use flagpole receptors                               No
 Fumigation           Inversion break-up                                   Yes
                      Shoreline fumigation                                 No
 Debug option         Yes
 Output file          Use non-default name                                 aerscreen_example.out




                                                         62
Figure 38. Plane view of building and stack orientation for example AERSCREEN run.

Table 4. Seasonal surface characteristics by sector.
                                                                   Sector
 Variable    Season
                        1       2       3       4        5       6        7      8       9      10      11      12
 Albedo      Winter    0.15    0.15    0.15    0.15     0.15    0.15    0.15    0.15    0.15    0.15    0.15    0.15
             Spring    0.14    0.14    0.14    0.14     0.14    0.14    0.14    0.14    0.14    0.14    0.14    0.14
             Summer    0.15    0.15    0.15    0.15     0.15    0.15    0.15    0.15    0.15    0.15    0.15    0.15
             Autumn    0.15    0.15    0.15    0.15     0.15    0.15    0.15    0.15    0.15    0.15    0.15    0.15
 Bowen       Winter    0.85    0.85    0.85    0.85     0.85    0.85    0.85    0.85    0.85    0.85    0.85    0.85
 ratio       Spring    0.63    0.63    0.63    0.63     0.63    0.63    0.63    0.63    0.63    0.63    0.63    0.63
             Summer    0.36    0.36    0.36    0.36     0.36    0.36    0.36    0.36    0.36    0.36    0.36    0.36
             Autumn    0.84    0.84    0.84    0.84     0.84    0.84    0.84    0.84    0.84    0.84    0.84    0.84
 Surface     Winter   0.089   0.011   0.025   0.029    0.032   0.034 0.031     0.013   0.115   0.244   0.391   0.305
 roughness   Spring   0.118   0.016   0.032   0.036     0.04   0.042 0.038     0.019   0.141   0.289   0.458   0.379
             Summer   0.143   0.022   0.038   0.043    0.048   0.049 0.045     0.025   0.163   0.335   0.509   0.435
             Autumn   0.123   0.016   0.032   0.036    0.041   0.042 0.038     0.019   0.142   0.311   0.478   0.405




                                                      63
Figure 39. a) land use pattern and sectors used for surface characteristics and b) terrain.
The circle represents the 1 km radius from the source.


 NED :
    ----------------------------------------------------
 NADGRIDS .\
 NED_22944813\NED_22944813.tif
Figure 40. Contents of demlist.txt for terrain processing.




                                             64
 units: METERS
 53
 105
 201
 503
 702
Figure 41. Contents of discrete_receptors.txt.



4.1 Processing and log file


Below in Figures 42 through 47 are the prompts and inputs for the source, building information,
terrain data and meteorological data. In Figure 39, the initial prompts are shown. Since there is
no existing AERSCREEN.INP file, AERSCREEN alerts the user that AERSCREEN.INP does
not exist and the user must enter the data. The user enters a title, whether the inputs are in
English or metric units, and the source type (point, volume, etc.).




Figure 42. Initial AERSCREEN title, units, and source type prompts.


After the initial prompts, the user then enters source parameters (Figure 43). The stack
parameters, stack height, inner stack diameter, stack exit temperature, stack velocity units, and
stack velocity. The user also enters if the source is urban or rural, and the urban population if an

                                                 65
urban source. The user then enters the minimum distance to ambient air, i.e. ambient boundary.
Values entered are as described in Table 3.




Figure 43. Source parameter inputs.


After source parameters have been entered, the user enters the building parameters for building
downwash effects (Figures 44 and 45). In Figure 44, the initial prompts are shown. The user is
prompted to include downwash if desired and if so, the user is prompted if an existing BPIPPRM
input file is to be used. If the answer is yes to downwash but no to an existing BPIPPRM file,
the user is then prompted for the building dimensions, building orientation, and stack orientation
relative to the building (Figure 45). The inputs are building height, maximum horizontal
dimension, minimum horizontal dimension, angle of maximum horizontal dimension to North,
angle of stack from North, and distance between stack and building center. Building dimensions
are shown in Table 3 and Figure 38.




Figure 44. Initial building downwash prompts.




                                               66
Figure 45. Building parameter inputs.


The next set of inputs is for terrain (Figure 46). The user is prompted if terrain is to be used.
The user is then prompted for the probe distance with a default of 10 km available. Note, that
the terrain input file or files (NED or DEM), must encompass the probe distance. Following the
probe distance, the user is prompted for the use of discrete receptors and then the user is
prompted for the use of flagpole receptors and if so, the flagpole height. After the flagpole
information, the source elevation is input by the user. This can be an elevation or the user can hit
<Enter> to use AERMAP to calculate elevation. In this case, the user has entered 126.8 m. Note
if terrain is not used, this is the last prompt in the terrain section of inputs. If terrain is to be
used, the user enters the coordinate type and coordinates. The NAD datum is also entered by the
user. If coordinates are UTM coordinates, the user will be prompted for the UTM zone. Since
geographic coordinates are used in this example, the UTM zone is determined by AERMAP.




Figure 46. Terrain parameter prompts.


                                                 67
The meteorological parameters are the next inputs by the user (Figure 47). The user enters the
minimum and maximum air temperatures for the AERSCREEN run or accepts defaults of 250
and 310 K. The user then enters the minimum wind speed and anemometer height. For this
example, a minimum of 1.5 m/s was selected for the wind speed and the default 10 m
anemometer height was entered. After the anemometer height, the surface characteristics type,
user-entered single values (option 1), AERMET seasonal tables (option 2), or use of an external
file (option 3) is chosen. Option 3, an external file, is chosen by the user and the user then enters
the filename. The file is in the same folder as the current working directory so no pathnames are
necessary. For the example, the surface friction velocity will not be adjusted. Figures 48 and 49
show the fumigation inputs and debug selection respectively. After processing the debug option,
the user is prompted for the name of the output file (Figure 50).




Figure 47. Meteorological parameter prompts and inputs.




Figure 48. Fumigation prompts.




                                                 68
Figure 49. Debug option input.




Figure 50. Output filename prompt and response.


Finally after the output file options, the validation page is displayed to the user listing all input
parameters for the source, building downwash, terrain, and meteorological data (Figure 51). The
source and building parameters are listed in both metric and English units as well as the
minimum and maximum temperatures, source elevation and probe distance. AERSCREEN also
displays the UTM and geographic coordinates for the source with the message that coordinates
were converted from geographic to UTM coordinates. Coordinates are displayed in NAD datum
of 1983. If coordinates were initially entered in NAD 1927 datum, those coordinates would be
listed as well with the message that coordinates were switched from NAD 27 to NAD 83 with
the NAD 27 geographic and UTM coordinates listed as well. The validation page indicates that
inversion break-up fumigation calculations will be performed and that the urban source will be
assumed to be rural for fumigation. Meteorological data are listed followed by the message that
the debug option is on and the name of the output file. The options listed below the output
filename can be used to change parameters for the source, building, terrain, meteorological data,
fumigation options, run title, debug option, and output filename. If options 1 through 6 are
chosen, the user then sees a sub-menu of parameters to choose (See Section 3). If the user is
ready to proceed, the user enters <Enter> and AERSCREEN begins processing the data. After
choosing to run AERSCREEN, the same data as seen on the validation page is written to the
AERSCREEN.LOG file (Figure 52).




                                                 69
Figure 51. Data validation page.
                                   70
Start date and time    04/22/21 10:41:06
                               AERSCREEN 21112

Example stack

            Example stack


         ----------------- DATA ENTRY VALIDATION -----------------
                        METRIC             ENGLISH
 ** STACKDATA ** ---------------     ----------------

 Emission Rate:        1.0000 g/s                7.937 lb/hr
 Stack Height:          20.00 meters             65.62 feet
 Stack Diameter:        0.500 meters             19.69 inches
 Stack Temperature:     300.0 K                   80.3 Deg F
 Exit Velocity:        15.000 m/s                49.21 ft/s
 Stack Flow Rate:        6240 ACFM
 Model Mode:            URBAN
 Population:          2400000
 Dist to Ambient Air:           30.0 meters               98. feet


 ** BUILDING DATA **

 Building Height:               34.0 meters             111.5 feet
 Max Building Dimension:       120.0 meters             393.7 feet
 Min Building Dimension:        60.0 meters             196.9 feet
 Building Orientation: 90.0 degrees
 Stack Direction:        26.6 degrees
 Stack Distance:         67.0 meters             219.8 feet


 ** TERRAIN DATA **

 Input coordinates switched from geographic to UTM

 Source Longitude: -78.78194 deg          700198. Easting
 Source Latitude:    35.89140 deg        3974176. Northing
 UTM Zone:          17          Reference Datum: 4 (NAD 83)
 Source Base Elevation: 126.8 meters      416.0 feet

 Probe distance:      1000. meters         3281. feet

 No flagpole receptors

 Using discrete receptors in
 discrete_receptors.txt

 Only receptors between the ambient and probe distances will be included
 Input distance units are: METERS


 ** FUMIGATION DATA **

 Urban source, assume rural for fumigation

 Inversion break-up fumigation requested


 ** METEOROLOGY DATA **

 Min/Max Temperature:    261.4 / 313.1 K    10.9 / 103.9 Deg F

 Minimum Wind Speed:        1.5 m/s

 Anemometer Height:      10.000 meters

 Using surface characteristics in file:
 aersurface_12.out

 Surface friction velocity (u*): not adjusted

DEBUG OPTION ON



 AERSCREEN output file:
 aerscreen_example.out


 *** AERSCREEN Run is Ready to Begin



 Terrain to be used,AERMAP will be run
**************************************************

Figure 52. Input data in AERSCREEN_EXAMPLE.LOG.
                                     71
After data validation, AERSCREEN reads the AERSURFACE output file and lists the surface
characteristics (Figure 53).

 SURFACE CHARACTERISTICS & MAKEMET
 Obtaining surface characteristics...

 Using seasonal surface characteristics for 12 spatial sector(s)
 Sector   Start End
    1        0     30
    2       30     60
    3       60     90
    4       90    120
    5      120    150
    6      150    180
    7      180    210
    8      210    240
    9      240    270
   10      270    300
   11      300    330
   12      330      0
 Season     Sector Albedo      Bo       zo
 Winter         1     0.15    0.85     0.089
 Winter         2     0.15    0.85     0.011
 Winter         3     0.15    0.85     0.025
 Winter         4     0.15    0.85     0.029
 Winter         5     0.15    0.85     0.032
 Winter         6     0.15    0.85     0.034
 Winter         7     0.15    0.85     0.031
 Winter         8     0.15    0.85     0.013
 Winter         9     0.15    0.85     0.115
 Winter        10     0.15    0.85     0.244
 Winter        11     0.15    0.85     0.391
 Winter        12     0.15    0.85     0.305
 Spring         1     0.14    0.63     0.118
 Spring         2     0.14    0.63     0.016
 .
 .
 .
 Autumn         11      0.15       0.84       0.478
 Autumn         12      0.15       0.84       0.405

 Creating met files aerscreen_01_01.sfc & aerscreen_01_01.pfl

 Creating met files aerscreen_01_02.sfc & aerscreen_01_02.pfl
 .
 .
 .
 Creating met files aerscreen_04_11.sfc & aerscreen_04_11.pfl

 Creating met files aerscreen_04_12.sfc & aerscreen_04_12.pfl
  ***************************************************
Figure 53. Surface characteristics processing and meteorological files creation.


                                             72
AERSCREEN then runs AERMAP for the source and determines the percent difference between
the user-entered source elevation and the AERMAP derived elevation (Figure 54). The
AERMAP elevation will not be used by AERSCREEN. AERSCREEN also lists any fatal error
or warning messages from AERMAP. In this case warning messages about the use of default
elevation units of meters for the NED file are displayed. For the example case, the difference
between the AERMAP elevation, 120.98 m, and the user-entered elevation, 126.8 m, differ by
4.59%.


 Running AERMAP for source
      *** AERMAP Finishes Successfully ***    for stage 0
     ********    WARNING MESSAGES   ********
  OU W473     26 NEDCHK:Default elevation units of METERS used; NED file:               1

 AERMAP elevation,    120.98 differs from user entered elevation,        126.80 by      4.59%
Figure 54. AERMAP processing and elevation of source.


Once AERMAP has been run for the source, AERSCREEN then begins the FLOWSECTOR
stage and executes AERMAP for the receptors (Figure 55). While processing the receptors,
AERMAP writes the processing status to the screen (Figure 56). Once AERMAP is completed
for all receptors for all thirty-six directions, AERSCREEN checks the AERMAP.OUT file for
any warnings or errors (Figure 57).


 Buildings and/or terrain present or rectangular area source, skipping probe

 FLOWSECTOR   started 04/22/21 10:42:43
  ***************************************************

 Running AERMAP for FLOWSECTOR
Figure 55. AERSCREEN_EXAMPLE.LOG records for AERMAP processing for
FLOWSECTOR.




                                              73
Figure 56. Status of AERMAP processing for FLOWSECTOR.




                                     74
         *** AERMAP Finishes Successfully ***  for stage 2
        ********   WARNING MESSAGES   ********
     OU W473 1462 NEDCHK:Default elevation units of METERS used; NED file:
 1
     ********************************************
Figure 57. AERSCREEN_EXAMPLE.LOG summary of AERMAP.OUT warning and
error messages.

Figure 58 shows partial AERMAP output for FLOWSECTOR. It is from this output that
AERSCREEN will extract the receptor elevations for AERMOD processing in FLOWSECTOR.
Receptor spacing for this example was 25 m since the probe distance was less than 5 km.
Summing across all 36 radials, excluding receptors less than the minimum ambient distance,
including the ambient distance, discrete receptors, and the source location, results in 1,621 total
receptors. Also listed in the output is information that will be used for later AERSCREEN runs
to determine if AERMAP needs to be rerun for FLOWSECTOR. This includes the UTM
coordinates, probe distance (meters), receptor spacing, UTM zone, NAD datum, number of NED
files and number of receptors. Coordinates, probe distance, receptor spacing, UTM zone, and
NAD datum are listed in the line after “** Example stack.”

 ** AERMAP - VERSION 18081                                                         04/22/21
 **                                                                                10:42:44
 ** Example stack
 **   700198.4 3974175.8    1000.0      25.0      25.0                  17         4
 ** A total of       1 NED files were used
 ** A total of    1621 receptors were processed
 ** DOMAINXY      699098.2   3973075.5 17     701298.2           3975275.5    17
 ** ANCHORXY           0.0         0.0        700198.2           3974175.5    17   4
 ** Terrain heights were extracted by default

 RE ELEVUNIT METERS
    DISCCART             0.00          0.00       120.98       120.98
    DISCCART             5.21         29.54       119.75       119.75
    DISCCART             8.68         49.24       119.60       119.60
    DISCCART             9.20         52.19       119.84       119.84
    DISCCART            13.02         73.86       120.82       120.82
    DISCCART            17.36         98.48       120.82       120.82
    DISCCART            18.23        103.40       120.81       120.81
    DISCCART            21.71        123.10       120.73       120.73
    DISCCART            26.05        147.72       120.36       120.36
    DISCCART            30.39        172.34       119.77       120.36
    DISCCART            34.73        196.96       117.76       120.49
    DISCCART            34.90        197.95       117.69       120.49
    DISCCART            39.07        221.58       117.96       117.96
Figure 58. Partial AERMAP output for FLOWSECTOR.


Once AERMAP has been run for all receptors, AERSCREEN processes each flow vector every
10 degrees from 10 degrees to 360 degrees. The appropriate building dimensions and
meteorological files are used for each flow vector. During processing, AERSCREEN notifies
the user what season or month and flow vector is being processed (Figure 59). A sample
AERMOD.INP file is shown in Figure 60 with projected building dimensions and receptors for a
particular flow vector. Note that the y-coordinate for each receptor is reset to 0. After

                                                75
AERMOD is executed for each flow vector, AERSCREEN checks the AERMOD.OUT file and
notifies the user of any warning or error messages for that flow vector (Figure 61).




Figure 59. AERSCREEN processing during FLOWSECTOR.




                                         76
SO STARTING
 LOCATION SOURCE POINT   0.0 0.0 126.80
 SRCPARAM SOURCE 0.1000E+01 10.000 300.000 15.000   0.500

    BUILDHGT SOURCE 36*34.00
    BUILDWID SOURCE 36*133.28
    BUILDLEN SOURCE 36*97.42
    XBADJ SOURCE 36*-115.27
    YBADJ SOURCE 36*7.70

    URBANSRC SOURCE

    SRCGROUP ALL

SO FINISHED


RE STARTING
** Fence line receptor
   DISCCART      30.0           0.0   120.90   120.90
** Automatic receptors
   DISCCART      50.0           0.0   120.84   120.84
   DISCCART      53.0           0.0   120.88   120.88
   DISCCART      75.0           0.0   121.31   121.31
.
.
.
 RE FINISHED
Figure 60. Partial AERMOD.INP file used in FLOWSECTOR for 20 degree flow vector.




                                          77
  Running AERMOD
 Processing Winter

 *****************************************************
 Processing wind flow sector 10

  AERMOD Finishes Successfully for FLOWSECTOR stage 2 Winter sector          10

          0 receptors skipped due to missing elevations
     ********   WARNING MESSAGES   ********
                *** NONE ***

 *****************************************************
 .
 .
 *****************************************************
 Processing wind flow sector 360

  AERMOD Finishes Successfully for FLOWSECTOR stage 2 Autumn sector 360

          0 receptors skipped due to missing elevations
     ********   WARNING MESSAGES   ********
                *** NONE ***

 FLOWSECTOR    ended 04/22/21 10:44:30
Figure 61. AERSCREEN_EXAMPLE.LOG partial output of AERMOD.OUT checks for
FLOWSECTOR.


After FLOWSECTOR, AERSCREEN enters the REFINE subroutine and calculates the overall
maximum concentration and its associated distance, flow vector, projected building dimensions,
terrain and meteorology. AERSCREEN then reruns AERMAP (Figure 62) and AERMOD with
refined receptor spacing using the terrain, projected building dimensions, and meteorology of the
maximum concentration’s flow vector. The receptors include the minimum ambient receptor
and receptors near the maximum concentration with 1 to 5 m spacing. See Figure 63 for the
partial AERMOD.INP file used in REFINE. Messages from AERSCREEN.LOG for REFINE
are shown in Figure 64. The maximum concentration is along the 160 degree flow vector.




                                               78
Figure 62. Status of AERMAP processing for REFINE.

                                       79
 SO STARTING
    LOCATION SOURCE POINT        0.0     0.0   126.80
    SRCPARAM SOURCE   0.1000E+01   20.000 300.000   15.000                  0.500

    BUILDHGT SOURCE      36*34.00
    BUILDWID SOURCE      36*133.28
    BUILDLEN SOURCE      36*97.42
    XBADJ    SOURCE      36*-2.68
    YBADJ    SOURCE      36*-48.68

    URBANSRC    SOURCE

    SRCGROUP    ALL

 SO FINISHED

 RE STARTING
 ** Fence line receptor
    DISCCART          30.00                 0.00        121.70        121.70
 ** Refined receptors
    DISCCART        125.00                  0.00        120.82        120.82
    DISCCART        126.00                  0.00        120.79        120.79
    DISCCART        127.00                  0.00        120.76        120.76
    DISCCART        128.00                  0.00        120.73        120.73
 .
 .
 RE FINISHED
Figure 63. Partial AERMOD.INP file for REFINE processing.



 REFINE       started 04/22/21 10:44:30
  ***************************************************

 Running AERMAP for REFINE
      *** AERMAP Finishes Successfully ***   for stage 3
     ********   WARNING MESSAGES   ********
  OU W473   123 NEDCHK:Default elevation units of METERS used; NED file:                1

  AERMOD Finishes Successfully for REFINE stage 3 Winter sector 160

         0 receptors skipped due to missing elevations
     ********   WARNING MESSAGES   ********
                *** NONE ***

 REFINE        ended 04/22/21 10:44:32




Figure 64. REFINE messages.

After REFINE, the inversion break-up fumigation calculations begin (Figure 65) and the final
messages are written to the AERSCREEN.LOG file. AERSCREEN ends and notifies the user
that AERSCREEN ended successfully with warnings and gives the end time.
                                             80
 FUMIGATE      started 04/22/21 10:44:33

  Calculating maximum distance of fumigation concentration

  **********************************************
  AERSCREEN Finished Successfully
  But with Warnings
  Source coordinates switched from lat/lon to UTM
         0 receptors skipped for FLOWSECTOR
         0 receptors skipped for REFINE
  Check log file for details
  ***********************************************

  Ending date and time    04/22/21 10:44:53
Figure 65. Fumigation and final AERSCREEN messages.

AERSCREEN also outputs the overall maximum 1-hour concentration, maximum 1-hour
ambient boundary concentration, and maximum 1-hour inversion break-up fumigation
concentration with scaled 3, 8, 24-hour, and annual average concentrations (Figure 66). Also
listed are the distances, flow vectors direction, and receptor elevations relative to the source
elevation. For the example case, the overall maximum 1-hour concentration was 215.6 µg/m3 at
171 m toward 160° and the receptor’s elevation was 6.12 m below the source or 122.68 m. The
maximum ambient boundary concentration was 149.4 µg/m3 north of the source at an elevation
of about 118.93 m or 7.87 m below the source elevation. The maximum concentration due to
inversion break-up was 0 µg/m3 at a distance of 100 m from the source. Because the distance is
less than 2 km, the concentration was set to zero within AERSCREEN.




                                               81
Figure 66. Overall maximum, maximum ambient boundary concentration, and maximum
inversion break-up fumigation concentration statistics.


4.2 AERSCREEN output


Output from AERSCREEN is written to AERSCREEN_EXAMPLE.OUT. Following are
sections with explanations.

The first section shown lists information also shown in the log file, emissions inputs, terrain
information (input terrain file and probe distance), and building inputs in both metric and English
units (Figure 67).




                                                82
 AERSCREEN 16216 / AERMOD 16216                                                      10/20/16
                                                                                     10:50:22

  TITLE: Example stack


 -----------------------------------------------------------------------------
  ***************************** STACK PARAMETERS ****************************
  -----------------------------------------------------------------------------

  SOURCE EMISSION RATE:                   1.0000 g/s                       7.937 lb/hr
  STACK HEIGHT:                            20.00 meters                    65.92 feet
  STACK INNER DIAMETER:                    0.500 meters                    19.69 inches
  PLUME EXIT TEMPERATURE:                  300.0 K                          80.3 Deg F
  PLUME EXIT VELOCITY:                    15.000 m/s                       49.21 ft/s
  STACK AIR FLOW RATE:                      6241 ACFM
  STACK BASE LONGITUDE:                 -78.7819 deg                     700198. Easting
  STACK BASE LATITUDE:                   35.8914 deg                    3974176. Northing
  STACK BASE UTM ZONE:                                                       17
  REFERENCE DATUM (NADA):                                                     4
  STACK BASE ELEVATION:                   126.80 meters                   416.01 feet
  RURAL OR URBAN:                          URBAN
  POPULATION:                            2400000

  DIGITAL ELEVATION MAP(S)                 NED_22944813\NED_22944813.tif

  INITIAL PROBE DISTANCE =                 1000. meters                    3281. feet



  -----------------------------------------------------------------------------
  *********************** BUILDING DOWNWASH PARAMETERS **********************
  -----------------------------------------------------------------------------

  BUILDING HEIGHT:                          34.0 meters                    111.5 feet
  MAX BUILDING DIMENSION:                  120.0 meters                    393.7 feet
  MIN BUILDING DIMENSION:                   60.0 meters                    196.9 feet
  BUILDING ORIENTATION TO NORTH:             90. degrees
  STACK DIRECTION FROM CENTER:               27. degrees
  STACK DISTANCE FROM CENTER:               67.0 meters                    219.8 feet

Figure 67. AERSCREEN_EXAMPLE.OUT section with source and building information.

The next section gives information about the results of FLOWSECTOR (Figure 68). The header
for the section gives the receptor spacing, 25 m. Next, follows the flow sectors from 10 to 360
degrees. Included for each sector are the projected building width and length output from
BPIPPRM, the x and y building adjustments from BPIPPRM, the maximum 1-hour
concentration (g/m3), the downwind distance from the source, and the elevation of the receptor
relative to the source (receptor – source). Concentrations are written in with the “G” FORTRAN
descriptor with 4 significant digits. The sector followed by an “*” indicates that this is the
highest concentration sector or “worst case sector.” In this case it is flow sector 160º with a
concentration of approximately 201.2 g/m3 at 175 m from the source. The relative receptor
                                                 83
elevation is -5.95 m, meaning the receptor is at an elevation of approximately 125.8 m. The
temporal period associated with the maximum concentration is winter.

 -----------------------------------------------------------------------------
  ************************** FLOW SECTOR ANALYSIS ***************************
                  25 meter receptor spacing: 30. meters - 1000. meters
 -----------------------------------------------------------------------------


                                                    MAXIMUM IMPACT RECEPTOR
       FLOW      BUILD   BUILD                     1-HR CONC   DIST   HEIGHT TEMPORAL
      SECTOR     WIDTH   LENGTH   XBADJ    YBADJ    (ug/m3)     (m)    (m)     PERIOD
      ----------------------------------------------------------------------------------
         10   128.60     79.93 -104.17     19.14   127.8        53.0   -7.02     WIN
         20   133.28     97.42 -115.27      7.70   117.7        30.0   -6.27     WIN
         30   133.92    111.96 -122.86     -3.97   83.83        30.0   -5.90     SUM
         40   130.49    123.10 -126.73    -15.53   62.52       150.0   -4.95     SPR
         50   123.10    130.49 -126.74    -26.61   60.34       150.0   -4.48     SPR
         60   111.96    133.92 -122.90    -36.88   89.96        75.0   -4.81     WIN
         70    97.42    133.28 -115.32    -46.04   94.09        75.0   -4.63     SPR
         80    79.93    128.60 -104.25    -53.79   167.1        53.0   -4.78     SPR
         90     0.00      0.00     0.00     0.00   59.91       325.0   -4.04     WIN
        100     0.00      0.00     0.00     0.00   59.40       350.0   -4.28     WIN
        110     0.00      0.00     0.00     0.00   58.83       325.0   -4.65     WIN
        120   111.96    133.92   -62.99   -66.88   173.8        75.0   -4.63     SPR
        130   123.10    130.49   -49.72   -65.18   171.9       100.0   -5.31     SPR
        140   130.49    123.10   -34.94   -61.49   177.1       125.0   -6.10     SPR
        150   133.92    111.96   -19.10   -55.94   195.4       150.0   -6.32     WIN
        160* 133.28      97.42    -2.68   -48.68   201.2       175.0   -5.95     WIN
        170   128.60     79.93    13.83   -39.95   196.7       175.0   -6.76     SPR
        180   120.00     60.00    29.91   -30.00   132.6       100.0   -5.14     WIN
        190   128.60     79.93    24.25   -19.14   147.6       105.0   -5.17     SPR
        200   133.28     97.42    17.85    -7.70   158.4       125.0   -5.34     SPR
        210   133.92    111.96    10.90     3.97   199.8       125.0   -5.69     SUM
        220   130.49    123.10     3.63    15.53   194.1       150.0   -6.42     WIN
        230   123.10    130.49    -3.76    26.61   172.6       125.0   -7.80     WIN
        240   111.96    133.92   -11.03    36.88   148.0       200.0 -13.12      WIN
        250    97.42    133.28   -17.96    46.04   164.7       150.0 -19.31      WIN
        260    79.93    128.60   -24.35    53.79   170.7       105.0 -21.97      SUM
        270     0.00      0.00     0.00     0.00   65.81       400.0 -13.94      WIN
        280     0.00      0.00     0.00     0.00   65.65       375.0 -21.22      WIN
        290     0.00      0.00     0.00     0.00   65.65       375.0 -23.80      WIN
        300   111.96    133.92   -70.94    66.88   157.1        75.0 -15.94      SPR
        310   123.10    130.49   -80.77    65.18   121.8       100.0 -12.98      WIN
        320   130.49    123.10   -88.16    61.49   122.8       100.0 -11.30      SUM
        330   133.92    111.96   -92.86    55.94   100.4       100.0 -11.07      WIN
        340   133.28     97.42   -94.75    48.68   64.08       150.0   -8.70     SPR
        350   128.60     79.93   -93.75    39.95   106.1        30.0   -8.58     WIN
        360   120.00     60.00   -89.91    30.00   149.4        30.0   -7.87     SPR
  * = worst case flow sector

Figure 68. FLOWSECTOR results in AERSCREEN_EXAMPLE.OUT.

Next, follows meteorological inputs and meteorology used to calculate the overall worst case
scenario (Figure 69). Listed first are the inputs: minimum and maximum temperatures (K),
minimum wind speed and anemometer height. Also listed is the dominant season and surface
roughness sector associated with the worst case concentration. For this case it is winter and
roughness sector 12 with beginning direction 330º and ending with 0º (or 360º). Note that this is
                                               84
the sector of the upwind direction of the worst case scenario. Shown below the season and
sector are the surface characteristics for that season and sector.

Next, follows the meteorological parameters used to predict the worst case concentration at the
ambient boundary (Figure 69): year, month, day, Julian date, hour, heat flux, u*, w*, lapse rate,
convective mixing height, mechanical mixing height, Monin-Obukhov length, surface roughness,
Bowen ratio, albedo reference wind speed, anemometer height, temperature, and temperature
measurement height (2 meters). The surface characteristics listed should match those listed in
association with the dominant season and sector in the AERSURFACE output file or
AERSCREEN.LOG file. After the meteorological parameters, the final plume rise is also
shown with stack top wind speeds. After that are listed the meteorological parameters and plume
height of the maximum concentration at the ambient boundary. Plume heights do not include
downwash effects.




                                               85
-----------------------------------------------------------------------------
 ********************** MAKEMET METEOROLOGY PARAMETERS *********************
 -----------------------------------------------------------------------------

 MIN/MAX TEMPERATURE:    261.4 / 313.1 (K)

 MINIMUM WIND SPEED:       1.5 m/s

 ANEMOMETER HEIGHT:      10.000 meters

 SURFACE CHARACTERISTICS INPUT: aersurface_12.out

 DOMINANT SECTOR:          12 (330   0)
 DOMINANT SEASON:          Winter

 ALBEDO:                  0.15
 BOWEN RATIO:             0.85
 ROUGHNESS LENGTH:       0.305 (meters)

 SURFACE FRICTION VELOCITY (U*) NOT ADUSTED

       METEOROLOGY CONDITIONS USED TO PREDICT OVERALL MAXIMUM IMPACT
       -------------------------------------------------------------

  YR MO DY JDY HR
  -- -- -- --- --
  10 01 14 14 12

     H0     U*     W* DT/DZ ZICNV ZIMCH M-O LEN      Z0 BOWEN ALBEDO REF WS
  - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
   4.72 0.185 0.600 0.020 1604. 183.       -117.1 0.305   0.85   0.15    1.50

     HT REF TA      HT
 - - - - - - - - - - -
   10.0   287.2    2.0

 WIND SPEED AT STACK HEIGHT (non-downwash):           1.7 m/s
 STACK-TIP DOWNWASH ADJUSTED STACK HEIGHT:           20.0 meters
 ESTIMATED FINAL PLUME RISE (non-downwash):          10.8 meters
 ESTIMATED FINAL PLUME HEIGHT (non-downwash):        30.8 meters


       METEOROLOGY CONDITIONS USED TO PREDICT AMBIENT BOUNDARY IMPACT
       --------------------------------------------------------------

  YR MO DY JDY HR
  -- -- -- --- --
  10 06 10 14 12

     H0     U*     W* DT/DZ ZICNV ZIMCH M-O LEN      Z0 BOWEN ALBEDO REF WS
  - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  34.75 0.239 1.200 0.020 1913. 268.        -37.7 0.038   0.63   0.14    3.00

     HT REF TA      HT
 - - - - - - - - - - -
   10.0   313.1    2.0

 WIND SPEED AT STACK HEIGHT (non-downwash):           3.3 m/s
 STACK-TIP DOWNWASH ADJUSTED STACK HEIGHT:           20.0 meters
 ESTIMATED FINAL PLUME RISE (non-downwash):           6.9 meters
 ESTIMATED FINAL PLUME HEIGHT (non-downwash):        26.9 meters

Figure 69. Meteorological data associated with maximum FLOWSECTOR concentration
and ambient boundary concentration.


                                                86
After the meteorological parameters, follows a summary of maximum concentrations by distance
(Figure 70). The concentrations shown are not necessarily in the same direction as the overall
maximum concentration shown in the flow sector analysis, i.e., the maximum 30 m
concentration may not be directed toward 180. Details about the concentrations’ meteorology
can be found in the file aerscreen_example_max_conc_distance.txt, whose format is listed in
Table 1. The maximum concentration and its distance, 175 m (shown in red in Figure 70) found
from FLOWSECTOR should be listed in the table and in
aerscreen_example_max_conc_distances.txt.

 -----------------------------------------------------------------------------
  ************************ AERSCREEN AUTOMATED DISTANCES **********************
                    OVERALL MAXIMUM CONCENTRATIONS BY DISTANCE
  -----------------------------------------------------------------------------


                 MAXIMUM   RECEPTOR                       MAXIMUM    RECEPTOR
         DIST   1-HR CONC   HEIGHT                DIST   1-HR CONC    HEIGHT
          (m)    (ug/m3)     (m)                  (m)    (ug/m3)       (m)
      ----------------------------             -----------------------------
         30.00   149.4        -7.87                503.00   132.1        -6.91
         50.00   166.9        -4.82                525.00   131.7        -7.24
         53.00   167.1        -4.78                550.00   130.2        -7.94
         75.00   173.8        -4.63                575.00   128.5        -8.66
        100.00   181.5        -5.30                600.00   127.4        -8.91
        105.00   180.7        -5.43                625.00   123.5       -10.77
        125.00   199.8        -5.69                650.00   123.0       -10.40
        150.00   199.5        -5.73                675.00   124.6        -8.89
        175.00   201.2        -5.95                700.00   126.4        -7.54
        200.00   193.8        -6.47                702.00   126.2        -7.55
        201.00   193.8        -6.47                725.00   124.8        -7.63
        225.00   126.5        -6.50                750.00   121.3        -8.42
        250.00   117.4        -5.87                775.00   116.6        -9.28
        275.00   115.4        -5.92                800.00   112.6        -9.90
        300.00   113.1        -6.01                825.00   108.9       -10.43
        325.00   110.7        -6.13                850.00   105.2       -11.04
        350.00   108.6       -13.95                875.00   101.7       -11.64
        375.00   112.2       -15.03                900.00   97.01       -13.40
        400.00   116.1       -14.10                925.00   92.22       -16.03
        425.00   120.5       -11.78                950.00   88.78       -17.60
        450.00   125.0        -9.54                975.00   86.55       -17.23
        475.00   130.1        -7.34               1000.00   84.33       -16.96
        500.00   132.0        -6.94
Figure 70. Summary of maximum concentrations by distance in
AERSCREEN_EXAMPLE.OUT.


The final section of the output file lists the results of REFINE and fumigation calculations
(Figure 71). The REFINE result is the overall maximum concentration in the direction of the
worst case scenario found in FLOWSECTOR, using the same surface characteristics (winter, 90
to 120 degrees sector). In addition to the 1-hour concentration calculated by AERMOD, the
scaled 3-hr, 8-hr, 24-hr, and annual concentrations are calculated by AERSCREEN and output.
Also output is the distance of the maximum concentration and its direction. Similar output is
listed for the maximum concentration at the minimum ambient distance. The maximum 1-hour

                                             87
inversion break-up fumigation concentration is listed along with the scaled 3-hr, 8-hr, 24-hr, and
annual concentrations.


 -----------------------------------------------------------------------------
  ********************** AERSCREEN MAXIMUM IMPACT SUMMARY *********************
  -----------------------------------------------------------------------------

                          MAXIMUM       SCALED          SCALED       SCALED       SCALED
                           1-HOUR       3-HOUR          8-HOUR      24-HOUR       ANNUAL
    CALCULATION             CONC         CONC            CONC         CONC         CONC
     PROCEDURE            (ug/m3)      (ug/m3)         (ug/m3)      (ug/m3)      (ug/m3)
  ---------------       ----------   ----------      ----------   ----------   ----------
  ELEVATED TERRAIN       215.6        215.6           194.0        129.3        21.56

  DISTANCE FROM SOURCE        171.00 meters directed toward 160 degrees
  RECEPTOR HEIGHT     -6.12 meters



  IMPACT AT THE
  AMBIENT BOUNDARY       149.4        149.4          134.5        89.65         14.94

  DISTANCE FROM SOURCE         30.00 meters directed toward 360 degrees
  RECEPTOR HEIGHT     -7.87 meters

  -----------------------------------------------------------------------------
  **********************   AERSCREEN FUMIGATION SUMMARY   *********************
  -----------------------------------------------------------------------------

                       MAXIMUM          SCALED          SCALED       SCALED       SCALED
                        1-HOUR          3-HOUR          8-HOUR      24-HOUR       ANNUAL
    FUMIGATION           CONC            CONC            CONC         CONC         CONC
     PROCEDURE         (ug/m3)         (ug/m3)         (ug/m3)      (ug/m3)      (ug/m3)
  ---------------    ----------      ----------      ----------   ----------   ----------
  INVERSION BREAK-UP   759.5           759.5           683.6        455.7        75.95


  DISTANCE FROM SOURCE            100.00 meters

Figure 71. Maximum concentration impact, ambient boundary, and inversion break-up
fumigation concentration summaries in AERSCREEN_EXAMPLE.OUT.


Figure 72 shows partial output for aerscreen_example_max_conc_distances.txt. Note that the
overall maximum concentration 215.6 g/m3 is denoted by the asterisk. See Table 2 for format.
Figure 73 shows partial output for the debug file, aerscreen_example_concentrations.txt. This
file has a similar format as aerscreen_example_max_conc_distances.txt, but lists the intermediate
outputs from FLOWSECTOR.




                                                88
 Concentration    Distance Elevation Flow Season/Month   Zo sector       Date       H0      U*     W* DT/DZ ZICNV ZIMCH M-O LEN    Z0 BOWEN ALBEDO REF WS     HT REF TA    HT
    0.14942E+03       30.00     -7.87  360      Spring      180-210   10061012    34.75   0.239 1.200 0.020 1913. 268.     -37.7 0.038  0.63   0.14   3.00   10.0  313.1   2.0
    0.16692E+03       50.00     -4.82   80      Spring      240-270   10020712   170.58   0.209 1.200 0.020 390. 219.       -5.1 0.141  0.63   0.14   1.50   10.0  313.1   2.0
    0.16713E+03       53.00     -4.78   80      Spring      240-270   10020712   170.58   0.209 1.200 0.020 390. 219.       -5.1 0.141  0.63   0.14   1.50   10.0  313.1   2.0
    0.17382E+03       75.00     -4.63  120      Spring      300-330   10012112    17.55   0.222 0.600 0.020 473. 241.      -59.9 0.458  0.63   0.14   1.50   10.0  313.1   2.0
    0.18151E+03      100.00     -5.30  160      Winter        330-0   10011412     4.75   0.185 0.600 0.020 1604. 183.    -117.1 0.305  0.85   0.15   1.50   10.0  287.2   2.0
    0.18070E+03      105.00     -5.43  160      Winter        330-0   10011412     4.75   0.185 0.600 0.020 1604. 183.    -117.1 0.305  0.85   0.15   1.50   10.0  287.2   2.0
    0.19976E+03      125.00     -5.69  210      Summer        30-60   10012812    11.90   0.117 0.600 0.020 698.     92.   -12.9 0.022  0.36   0.15   1.50   10.0  313.1   2.0
    0.19948E+03      150.00     -5.73  210      Summer        30-60   10012812    11.90   0.117 0.600 0.020 698.     92.   -12.9 0.022  0.36   0.15   1.50   10.0  313.1   2.0
 * 0.21555E+03       171.00     -6.12  160      Winter        330-0   10011412     4.72   0.200 0.600 0.020 1615. 205.    -148.4 0.405  0.84   0.15   1.50   10.0  287.2   2.0
    0.20123E+03      175.00     -5.95  160      Winter        330-0   10011412     4.75   0.185 0.600 0.020 1604. 183.    -117.1 0.305  0.85   0.15   1.50   10.0  287.2   2.0
    0.19380E+03      200.00     -6.47  220      Winter        30-60   10011412     4.75   0.100 0.600 0.020 1604.    73.   -18.6 0.011  0.85   0.15   1.50   10.0  287.2   2.0
    0.19380E+03      201.00     -6.47  220      Winter        30-60   10011412     4.75   0.100 0.600 0.020 1604.    73.   -18.6 0.011  0.85   0.15   1.50   10.0  287.2   2.0
    0.12648E+03      225.00     -6.50  220      Winter        30-60   10012301    -0.43   0.082 -9.000 0.020 -999.   54.   102.6 0.011  0.85   0.15   1.50   10.0  261.4   2.0
    0.11743E+03      250.00     -5.87  210      Winter        30-60   10012301    -0.43   0.082 -9.000 0.020 -999.   54.   102.6 0.011  0.85   0.15   1.50   10.0  261.4   2.0
    0.11541E+03      275.00     -5.92  210      Winter        30-60   10012301    -0.43   0.082 -9.000 0.020 -999.   54.   102.6 0.011  0.85   0.15   1.50   10.0  261.4   2.0
    0.11313E+03      300.00     -6.01  210      Winter        30-60   10012301    -0.43   0.082 -9.000 0.020 -999.   54.   102.6 0.011  0.85   0.15   1.50   10.0  261.4   2.0
    0.11075E+03      325.00     -6.13  210      Winter        30-60   10012301    -0.43   0.082 -9.000 0.020 -999.   54.   102.6 0.011  0.85   0.15   1.50   10.0  261.4   2.0
    0.10857E+03      350.00    -13.95  360      Summer      180-210   10012501    -2.31   0.056 -9.000 0.020 -999.   30.     7.1 0.045  0.36   0.15   1.50   10.0  313.1   2.0
    0.11220E+03      375.00    -15.03  360      Summer      180-210   10012501    -2.31   0.056 -9.000 0.020 -999.   30.     7.1 0.045  0.36   0.15   1.50   10.0  313.1   2.0
    0.11611E+03      400.00    -14.10  360      Summer      180-210   10012501    -2.31   0.056 -9.000 0.020 -999.   30.     7.1 0.045  0.36   0.15   1.50   10.0  313.1   2.0
    0.12050E+03      425.00    -11.78  360      Summer      180-210   10012501    -2.31   0.056 -9.000 0.020 -999.   30.     7.1 0.045  0.36   0.15   1.50   10.0  313.1   2.0
    0.12498E+03      450.00     -9.54  360      Summer      180-210   10012501    -2.31   0.056 -9.000 0.020 -999.   30.     7.1 0.045  0.36   0.15   1.50   10.0  313.1   2.0
    0.13014E+03      475.00     -7.34  360      Summer      180-210   10012501    -2.31   0.056 -9.000 0.020 -999.   30.     7.1 0.045  0.36   0.15   1.50   10.0  313.1   2.0
    0.13197E+03      500.00     -6.94  360      Summer      180-210   10012501    -2.31   0.056 -9.000 0.020 -999.   30.     7.1 0.045  0.36   0.15   1.50   10.0  313.1   2.0
    0.13213E+03      503.00     -6.91  360      Summer      180-210   10012501    -2.31   0.056 -9.000 0.020 -999.   30.     7.1 0.045  0.36   0.15   1.50   10.0  313.1   2.0
    0.13175E+03      525.00     -7.24  360      Summer      180-210   10012501    -2.31   0.056 -9.000 0.020 -999.   30.     7.1 0.045  0.36   0.15   1.50   10.0  313.1   2.0
    0.13025E+03      550.00     -7.94  360      Summer      180-210   10012501    -2.31   0.056 -9.000 0.020 -999.   30.     7.1 0.045  0.36   0.15   1.50   10.0  313.1   2.0
    0.12848E+03      575.00     -8.66  360      Summer      180-210   10012501    -2.31   0.056 -9.000 0.020 -999.   30.     7.1 0.045  0.36   0.15   1.50   10.0  313.1   2.0
    0.12741E+03      600.00     -8.91  360      Summer      180-210   10012501    -2.31   0.056 -9.000 0.020 -999.   30.     7.1 0.045  0.36   0.15   1.50   10.0  313.1   2.0
    0.12347E+03      625.00    -10.77  360      Summer      180-210   10012501    -2.31   0.056 -9.000 0.020 -999.   30.     7.1 0.045  0.36   0.15   1.50   10.0  313.1   2.0
    0.12298E+03      650.00    -10.40  360      Summer      180-210   10012501    -2.31   0.056 -9.000 0.020 -999.   30.     7.1 0.045  0.36   0.15   1.50   10.0  313.1   2.0
    0.12457E+03      675.00     -8.89  360      Spring      180-210   10012501    -2.21   0.054 -9.000 0.020 -999.   29.     6.8 0.038  0.63   0.14   1.50   10.0  313.1   2.0
    0.12637E+03      700.00     -7.54  360      Spring      180-210   10012501    -2.21   0.054 -9.000 0.020 -999.   29.     6.8 0.038  0.63   0.14   1.50   10.0  313.1   2.0
    0.12624E+03      702.00     -7.55  360      Spring      180-210   10012501    -2.21   0.054 -9.000 0.020 -999.   29.     6.8 0.038  0.63   0.14   1.50   10.0  313.1   2.0
    0.12479E+03      725.00     -7.63  360      Spring      180-210   10012501    -2.21   0.054 -9.000 0.020 -999.   29.     6.8 0.038  0.63   0.14   1.50   10.0  313.1   2.0
    0.12125E+03      750.00     -8.42  360      Spring      180-210   10012501    -2.21   0.054 -9.000 0.020 -999.   29.     6.8 0.038  0.63   0.14   1.50   10.0  313.1   2.0
    0.11656E+03      775.00     -9.28  360      Spring      180-210   10012501    -2.21   0.054 -9.000 0.020 -999.   29.     6.8 0.038  0.63   0.14   1.50   10.0  313.1   2.0
    0.11257E+03      800.00     -9.90  360      Spring      180-210   10012501    -2.21   0.054 -9.000 0.020 -999.   29.     6.8 0.038  0.63   0.14   1.50   10.0  313.1   2.0
    0.10888E+03      825.00    -10.43  360      Spring      180-210   10012501    -2.21   0.054 -9.000 0.020 -999.   29.     6.8 0.038  0.63   0.14   1.50   10.0  313.1   2.0
    0.10522E+03      850.00    -11.04  360      Spring      180-210   10012501    -2.21   0.054 -9.000 0.020 -999.   29.     6.8 0.038  0.63   0.14   1.50   10.0  313.1   2.0
    0.10171E+03      875.00    -11.64  360      Spring      180-210   10012501    -2.21   0.054 -9.000 0.020 -999.   29.     6.8 0.038  0.63   0.14   1.50   10.0  313.1   2.0
    0.97014E+02      900.00    -13.40  360      Spring      180-210   10012501    -2.21   0.054 -9.000 0.020 -999.   29.     6.8 0.038  0.63   0.14   1.50   10.0  313.1   2.0
    0.92219E+02      925.00    -16.03  360      Spring      180-210   10012501    -2.21   0.054 -9.000 0.020 -999.   29.     6.8 0.038  0.63   0.14   1.50   10.0  313.1   2.0
    0.88779E+02      950.00    -17.60  360      Spring      180-210   10012501    -2.21   0.054 -9.000 0.020 -999.   29.     6.8 0.038  0.63   0.14   1.50   10.0  313.1   2.0
    0.86548E+02      975.00    -17.23  360      Spring      180-210   10012501    -2.21   0.054 -9.000 0.020 -999.   29.     6.8 0.038  0.63   0.14   1.50   10.0  313.1   2.0
    0.84328E+02     1000.00    -16.96  360      Spring      180-210   10012501    -2.21   0.054 -9.000 0.020 -999.   29.     6.8 0.038  0.63   0.14   1.50   10.0  313.1   2.0

Figure 72. Output of aerscreen_example_max_conc_distance.txt.




                                                                                     89
 Concentration    Distance Elevation Flow Season/Month   Zo sector       Date       H0      U*     W* DT/DZ ZICNV ZIMCH M-O LEN    Z0 BOWEN ALBEDO REF WS     HT REF TA    HT
    0.12767E+03       30.00     -7.06   10      Winter      180-210   10080512    80.98   0.308 1.800 0.020 2770. 393.     -34.6 0.031  0.85   0.15   4.00   10.0  313.1   2.0
    0.11768E+03       30.00     -6.27   20      Winter      180-210   10080512    80.98   0.308 1.800 0.020 2770. 393.     -34.6 0.031  0.85   0.15   4.00   10.0  313.1   2.0
    0.83517E+02       30.00     -5.90   30      Winter      210-240   10032501   -21.38   0.198 -9.000 0.020 -999. 203.     35.0 0.013  0.85   0.15   4.00   10.0  313.1   2.0
    0.42414E+02       30.00     -5.65   40      Winter      210-240   10110912   286.89   0.632 1.800 0.020 782. 1157.     -84.8 0.013  0.85   0.15  10.00   10.0  313.1   2.0
    0.39925E+02       30.00     -5.43   50      Winter      210-240   10011001    -2.39   0.045 -9.000 0.020 -999. 110.      3.7 0.013  0.85   0.15   1.50   10.0  313.1   2.0
    0.49116E+02       30.00     -5.25   60      Winter      240-270   10011812    40.89   0.172 0.600 0.020 203. 165.      -12.0 0.115  0.85   0.15   1.50   10.0  313.1   2.0
    0.46231E+02       30.00     -5.17   70      Winter      240-270   10010812    45.67   0.174 0.600 0.020 182. 167.      -11.2 0.115  0.85   0.15   1.50   10.0  313.1   2.0
    0.11514E+03       30.00     -5.10   80      Winter      240-270   10021712   286.89   0.212 1.800 0.020 782. 225.       -3.2 0.115  0.85   0.15   1.50   10.0  313.1   2.0
    0.77764E+01       30.00     -5.05   90      Winter      270-300   10011612    54.56   0.210 0.600 0.020 140. 222.      -15.1 0.244  0.85   0.15   1.50   10.0  287.2   2.0
    0.77789E+01       30.00     -5.01  100      Winter      270-300   10011612    54.56   0.210 0.600 0.020 140. 222.      -15.1 0.244  0.85   0.15   1.50   10.0  287.2   2.0
    0.77802E+01       30.00     -4.99  110      Winter      270-300   10011612    54.56   0.210 0.600 0.020 140. 222.      -15.1 0.244  0.85   0.15   1.50   10.0  287.2   2.0
    0.68684E+02       30.00     -4.98  120      Winter      300-330   10020312    24.98   0.220 1.200 0.020 2441. 237.     -37.7 0.391  0.85   0.15   1.50   10.0  287.2   2.0
    0.69684E+02       30.00     -5.00  130      Winter      300-330   10020612    40.89   0.228 1.200 0.020 1626. 250.     -27.8 0.391  0.85   0.15   1.50   10.0  313.1   2.0
    0.69040E+02       30.00     -5.02  140      Winter      300-330   10011412     4.75   0.198 0.600 0.020 1604. 202.    -143.2 0.391  0.85   0.15   1.50   10.0  287.2   2.0
    0.69988E+02       30.00     -5.05  150      Winter        330-0   10011412     4.75   0.185 0.600 0.020 1604. 183.    -117.1 0.305  0.85   0.15   1.50   10.0  287.2   2.0
    0.61306E+02       30.00     -5.10  160      Winter        330-0   10011412     4.75   0.185 0.600 0.020 1604. 183.    -117.1 0.305  0.85   0.15   1.50   10.0  287.2   2.0
    0.33467E+02       30.00     -5.19  170      Winter        330-0   10020612    40.89   0.214 1.200 0.020 1626. 227.     -23.0 0.305  0.85   0.15   1.50   10.0  313.1   2.0
    0.19780E+00       30.00     -5.29  180      Winter        330-0   10010812    45.67   0.216 0.600 0.020 182. 231.      -21.2 0.305  0.85   0.15   1.50   10.0  313.1   2.0
    0.10403E+02       30.00     -5.40  190      Winter         0-30   10010412     4.75   0.140 0.300 0.020 201. 121.      -51.3 0.089  0.85   0.15   1.50   10.0  287.2   2.0
    0.18922E+02       30.00     -5.51  200      Winter         0-30   10011412     4.75   0.140 0.600 0.020 1604. 121.     -51.3 0.089  0.85   0.15   1.50   10.0  287.2   2.0
    0.33730E+02       30.00     -5.64  210      Winter        30-60   10011412     4.75   0.100 0.600 0.020 1604.    73.   -18.6 0.011  0.85   0.15   1.50   10.0  287.2   2.0
    0.42504E+02       30.00     -5.79  220      Winter        30-60   10011412     4.75   0.100 0.600 0.020 1604.    73.   -18.6 0.011  0.85   0.15   1.50   10.0  287.2   2.0
    0.48038E+02       30.00     -5.92  230      Winter        30-60   10010312     1.95   0.096 0.300 0.020 445.     68.   -36.5 0.011  0.85   0.15   1.50   10.0  261.4   2.0
    0.47331E+02       30.00     -6.31  240      Winter        60-90   10010312     1.95   0.108 0.300 0.020 445.     82.   -52.3 0.025  0.85   0.15   1.50   10.0  261.4   2.0
    0.47690E+02       30.00     -7.11  250      Winter        60-90   10011412     4.75   0.113 0.600 0.020 1604.    87.   -26.6 0.025  0.85   0.15   1.50   10.0  287.2   2.0
    0.47666E+02       30.00     -8.02  260      Winter        60-90   10011412     4.75   0.113 0.600 0.020 1604.    87.   -26.6 0.025  0.85   0.15   1.50   10.0  287.2   2.0
    0.49551E+01       30.00     -8.91  270      Winter       90-120   10011612    54.56   0.140 0.600 0.020 140. 120.       -4.4 0.029  0.85   0.15   1.50   10.0  287.2   2.0
    0.49548E+01       30.00     -9.64  280      Winter       90-120   10011612    54.56   0.140 0.600 0.020 140. 120.       -4.4 0.029  0.85   0.15   1.50   10.0  287.2   2.0
    0.49547E+01       30.00    -10.10  290      Winter       90-120   10011612    54.56   0.140 0.600 0.020 140. 120.       -4.4 0.029  0.85   0.15   1.50   10.0  287.2   2.0
    0.69511E+02       30.00    -10.18  300      Winter      120-150   10020612    40.89   0.137 1.200 0.020 1626. 116.      -6.0 0.032  0.85   0.15   1.50   10.0  313.1   2.0
    0.65020E+02       30.00    -10.00  310      Winter      120-150   10012412   126.56   0.153 1.200 0.020 525. 137.       -2.7 0.032  0.85   0.15   1.50   10.0  313.1   2.0
    0.77417E+02       30.00     -9.74  320      Winter      120-150   10012412   126.56   0.153 1.200 0.020 525. 137.       -2.7 0.032  0.85   0.15   1.50   10.0  313.1   2.0
    0.61248E+02       30.00     -9.42  330      Winter      150-180   10010812    45.67   0.140 0.600 0.020 182. 120.       -5.8 0.034  0.85   0.15   1.50   10.0  313.1   2.0
    0.36388E+02       30.00     -9.11  340      Winter      150-180   10011001    -3.03   0.053 -9.000 0.020 -999. 139.      4.7 0.034  0.85   0.15   1.50   10.0  313.1   2.0
    0.10606E+03       30.00     -8.58  350      Winter      150-180   10080512    80.98   0.312 1.800 0.020 2770. 401.     -36.2 0.034  0.85   0.15   4.00   10.0  313.1   2.0
    0.13881E+03       30.00     -7.87  360      Winter      180-210   10030901    -7.46   0.138 -9.000 0.020 -999. 117.     33.6 0.031  0.85   0.15   2.50   10.0  313.1   2.0
    0.12608E+03       30.00     -7.06   10      Spring      180-210   10082512    92.36   0.320 1.800 0.020 2429. 417.     -34.2 0.038  0.63   0.14   4.00   10.0  313.1   2.0
    0.11738E+03       30.00     -6.27   20      Spring      180-210   10082512    92.36   0.320 1.800 0.020 2429. 417.     -34.2 0.038  0.63   0.14   4.00   10.0  313.1   2.0
    0.83710E+02       30.00     -5.90   30      Spring      210-240   10032401   -23.02   0.213 -9.000 0.020 -999. 227.     40.6 0.019  0.63   0.14   4.00   10.0  313.1   2.0
    0.42338E+02       30.00     -5.65   40      Spring      210-240   10121312   244.32   0.665 1.800 0.020 918. 1248.    -115.9 0.019  0.63   0.14  10.00   10.0  313.1   2.0
    0.39489E+02       30.00     -5.43   50      Spring      210-240   10011001    -2.61   0.048 -9.000 0.020 -999. 120.      4.0 0.019  0.63   0.14   1.50   10.0  313.1   2.0
    0.48878E+02       30.00     -5.25   60      Spring      240-270   10012212    34.75   0.177 0.600 0.020 239. 171.      -15.3 0.141  0.63   0.14   1.50   10.0  313.1   2.0



Figure 73. Partial output of aerscreen_example_concentrations.txt.




                                                                                     90
With the debug option turned on, the fumigation debug file,
aerscreen_example_fumigate_debug.txt was created. This file lists the iterative process used to
calculate the effective plume height for each hour of meteorology that is used in the fumigation
calculations (Figure 74). The file also lists the iterative process of calculating the distance Xmax
for inversion break-up fumigation and subsequent concentration, f (Figure 75).


 Calculating effective plume height for: 10010401

  Stack height (adjusted):    20.00 m
  Initial plume rise:    11.93 m

  Iteration: 1
  Plume height:          25.97 m
  Plume rise:          13.20 m

  Iteration: 2
  Plume height:          26.60 m
  Plume rise:          13.18 m

  Final plume rise
  Iteration: 2
  Effective Plume height:              33.18 m
  Plume rise:    13.18 m

  Calculating effective plume height for: 10010501

  Stack height (adjusted):    20.00 m
  Initial plume rise:    11.93 m

  Iteration: 1
  Plume height:          25.97 m
  Plume rise:          13.20 m

  Iteration: 2
  Plume height:          26.60 m
  Plume rise:          13.18 m

  Final plume rise
  Iteration: 2
  Effective Plume height:              33.18 m
  Plume rise:    13.18 m
Figure 74. Partial output of aerscreen_example_fumigate_debug.txt showing effective
plume height calculations.




                                                 91
 ######################################################################################
  INVERSION BREAK-UP FUMIGATION CALCULATIONS FOR 10010401

 Stack height:   20.00 m
 Stack height wind speed 2.5 m
 Stack-tip downwash adjusted stack height:   20.00 m
 Effective stack height:   33.18 m
 Initial distance:      5.000 km
 temporal period: 1
 spatial sector: 1

 BASE METEOROLOGICAL VARIABLES
     H0     U*     W* DT/DZ ZICNV ZIMCH M-O LEN      Z0 BOWEN ALBEDO REF WS
  - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  -3.35 0.064 -9.000 0.020 -999.     37.      6.2 0.089   0.85   0.15    1.50

     HT REF TA      HT
 - - - - - - - - - - -
   10.0   261.4    2.0

 OTHER VARIABLES

   UMIX       UEFF SIG-V SIG-W     THETA DT/DZ_2     BV    SIG-YB SIGZ-B
 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      3.2     3.1    0.20    0.06   266.3 0.0921 0.0582       3.7     3.7

 Iteration   1

 Sigma-y: 0.160E+03 m
 Sigma-z: 0.872E+01 m
 Distance:       0.408 km

 Iteration   2

 Sigma-y: 0.226E+02 m
 Sigma-z: 0.428E+01 m
 Distance:       0.253 km

 Iteration   3

 Sigma-y: 0.151E+02 m
 Sigma-z: 0.406E+01 m
 Distance:       0.247 km

 Convergence found at iteration   3

 Sigma-y: 0.148E+02 m
 Sigma-z: 0.405E+01 m
 Concentration: 0.205E+03

 DISTANCE 0.247 < 2 KM, RESET CHI TO 0
 NEW MAX CONCENTRATION OF 0.000E+00 AT       0.247 KM FOR DATE 10010401 temporal period:   1
  spatial sector: 1


Figure 75. Partial output of aerscreen_example_fumigate_debug.txt showing
concentration calculations.




                                               92
After processing, AERSCREEN creates a new AERSCREEN.INP file, with any user input
changes added (Figure 76). Note that any options are that are alphabetic have been set to
uppercase. AERSCREEN sets all flags to uppercase internally for program efficiency.
AERSCREEN will also output the surface characteristics for the maximum concentration as the
user-entered values in the MAKEMET DATA section and lists the time, flow vector, and surface
roughness sector of the overall maximum concentration. AERSCREEN also copies the new
AERSCREEN.INP file to AERSCREEN_EXAMPLE.INP and AERSCREEN.LOG to
AERSCREEN_EXAMPLE.LOG.




                                            93
 ** Coordinates switched from geographic to UTM
 ** STACK DATA         Rate    Height     Temp.         Velocity         Diam.        Flow
 **              0.1000E+01   20.0000 300.0000           15.0000        0.5000        6241.

 ** BUILDING DATA     BPIP      Height    Max dim.   Min dim.      Orient.     Direct.      Offset
 **                    Y       34.0000    120.0000    60.0000      90.0000     26.6000     67.0000

 ** MAKEMET DATA      MinT     MaxT Speed     AnemHt Surf Clim       Albedo      Bowen Length SC FILE
 **                 261.40   313.10   1.5     10.000    9    0        0.1500      0.8500  0.3050 "aersurface_12.out"

 ** ADJUST U*        N

 ** TERRAIN DATA     Terrain      UTM East     UTM North    Zone    Nada       Probe       PROFBASE Use AERMAP elev
 **                     Y         700198.2     3974175.5      17       4         1000.0           126.80        N

 ** DISCRETE RECEPTORS     Discflag      Receptor file
 **                         Y           "discrete_receptors.txt"

 ** UNITS/POPULATION      Units   R/U    Population         Amb. dist.       Flagpole      Flagpole height
 **                         M     U        2400000.             30.000           N           0.00

 ** FUMIGATION           Inversion Break-up     Shoreline    Distance        Direct     Run AERSCREEN
 **                            Y                     N           0.00          0.0        Y

 ** DEBUG OPTION         Debug
 **                        Y

 ** OUTPUT FILE "aerscreen_example.out"

 ** Temporal sector: Winter, flow vector: 160 degrees, spatial sector: 12
Figure 76. Header portion of new AERSCREEN.INP file.




                                                                   94
5. References

Hanrahan, P.L., 1999a. "The plume volume molar ratio method for determining NO2/NOx ratios
      in modeling. Part I: Methodology," Journal of the Air & Waste
      Management Association, 49, 1324-1331.

Hanrahan, P.L., 1999b. "The plume volume molar ratio method for determining NO2/NOx ratios
      in modeling. Part II: Evaluation Studies," Journal of the Air & Waste
      Management Association, 49, 1332-1338.

Leahey, D.M., and M. J. E. Davies, 1984: Observations of Plume Rise From Sour Gas Flares.
      Atmospheric Environment, Vol. 18, pp. 917-922.

Schulman, L.L., D.G. Strimaitis, and J.S. Scire, 2000: Development and Evaluation of the
      PRIME Plume Rise and Building Downwash Model. Journal of the Air & Waste
      Management Association, Vol. 50, pp 378-390.

Turner, D.B., 1970: Workbook of Atmospheric Dispersion Estimates. Revised, Sixth Printing,
       January 1973. Office of Air Programs Publication No. AP-26.

U.S. EPA, 1992: Screening Procedures for Estimating the Air Quality Impact of Stationary
       Sources. EPA-454/R-92-019. U.S. Environmental Protection Agency, Research Triangle
       Park, NC 27711.

U.S. EPA, 1995: SCREEN3 Model User’s Guide. EPA-454/B-95-004. U.S. Environmental
       Protection Agency, Research Triangle Park, NC 27711.

U.S. EPA, 2004: User's Guide to the Building Profile Input Program. EPA-454/R-93-038. U.S.
       Environmental Protection Agency, Research Triangle Park, North Carolina 27711.

U.S. EPA, 2016. Guideline on Air Quality Models. 40 CFR Part 51 Appendix W.

U.S. EPA, 2018: User's Guide for the AERMOD Terrain Preprocessor
       (AERMAP). EPA-454/B-18-004. U.S. Environmental Protection Agency, Research
       Triangle Park, North Carolina 27711.

U.S. EPA, 2020: User’s Guide for AERSURFACE Tool. EPA-454/B-20-008. U.S.
       Environmental Protection Agency, Research Triangle Park, North Carolina 27711.

U.S. EPA, 2021a: User's Guide for the AMS/EPA Regulatory Model – AERMOD. EPA-454/B-
       21-001. U.S. Environmental Protection Agency, Research Triangle Park, NC 27711.




                                              95
U.S. EPA, 2021b: User's Guide for the AERMOD Meteorological
       Preprocessor (AERMET). EPA-454/B-21-005. U.S. Environmental Protection Agency,
       Research Triangle Park, North Carolina 27711.

U.S. EPA, 2021c: AERMOD Implementation Guide. EPA-454/B-21-002. U.S. Environmental
       Protection Agency, Research Triangle Park, North Carolina 27711.




                                          96
Appendix A. Input parameters and invalid responses

    Below, AERSCREEN input parameters are listed with invalid responses and actions taken by
AERSCREEN when reading the data from the AERSCREEN.INP file or prompts. Some
variables are only checked if the appropriate flags are set. Building dimensions are not checked
if downwash is not included in AERSCREEN processing. Other variables such as urban
population or flagpole heights are not checked if the source is not urban or flagpole receptors are
not used.

    As previously noted, when reading data from AERSCREEN.INP, if any of the data sections,
emissions, building information, terrain information, meteorological information, and other
parameters, is missing, AERSCREEN will alert the user and stop processing. If the emissions
data is listed after the building, terrain, or other parameter data sections, AERSCREEN will alert
the user and stop processing.




                                               A-1
Source parameters and invalid values.
        Parameter                  Source type                                   Invalid response                                      AERSCREEN.INP                          Prompts
 Units flag                  All                      If prompts, response is not upper or lower case E or M. If input file,   Issue message and stop                  Re-prompt
                                                      response is not upper or lowercase M.
 Source type                 All                      Response is not upper or lower-case: P, F, H, A, C, S, or V              Issue message and stop                  Re-prompt
 Emission rate               All                      Negative or non-numeric                                                  Issue message and stop                  Re-prompt
 Stack height                Point, capped stack,     Negative or non-numeric                                                  Issue message and stop                  Re-prompt
                             horizontal stack
 Stack diameter              Point, capped stack,     Negative or non-numeric                                                  Issue message and stop                  Re-prompt
                             horizontal stack
 Negative exit velocity      Point, capped stack,     Non-numeric                                                              Issue message and reset to 1x10-5 m/s   Issue message and reset to
                             horizontal stack                                                                                  if negative                             1x10-5 m/s if negative
 Flare height                Flare                    Negative or non-numeric                                                  Issue message and stop                  Re-prompt
 Heat release rate           Flare                    Negative or non-numeric                                                  Issue message and stop                  Re-prompt
 Heat loss fraction          Flare                    Non-numeric                                                              Issue message and reset to 0 if         Issue message and reset to
                                                                                                                               negative                                0 if negative
 Release height              Area, volume, circular   Negative or non-numeric                                                  Issue message and stop                  Re-prompt
                             area
 Initial vertical            Area, volume, circular   Negative or non-numeric                                                  Issue message and stop                  Re-prompt
 dimension                   area
 Initial lateral dimension   Volume                   Negative or non-numeric                                                  Issue message and stop                  Re-prompt
 Circular radius             Circular area            Negative or non-numeric                                                  Issue message and stop                  Re-prompt
 Rectangular area source     Area                     Negative or non-numeric                                                  Issue message and stop                  Re-prompt
 horizontal dimensions
 Orientation angle           Area                     Non-numeric or non-zero                                                  Issue message and stop                  N/A
 Number of vertices          Circular area            Non-numeric or not equal to 20                                           Issue message and stop                  N/A
 Urban/rural flag            All                      Response is not upper or lower-case Y or N                               Issue message and stop                  Re-prompt
 Urban population            All                      Non-numeric, negative or less than 100 people                            Issue message and stop (if source is    Re-prompt
                                                                                                                               urban)
 Minimum ambient             All                      Non-numeric, negative or if volume source, inside the volume.            Issue message and reset to minimum      Re-prompt if non-numeric
 distance                                                                                                                      distance based on source type if
                                                                                                                               negative. If non-numeric issue
                                                                                                                               message and stop
 NO2 conversion method       All                      “PVMRM” and “OLM” are both on MODELOPT card or                           Issue message and stop                  N/A
                                                      POLLUTID is NO2 and neither PVMRM or OLM is on
                                                      MODELOPT card
 NO2/NOX in-stack ratio      All                      Non-numeric, negative, or exceeds 1.0                                    Issue message and stop                  Re-prompt
 Ozone background            All                      Non-numeric, negative, or exceeds 1.0                                    Issue message and stop                  Re-prompt
 concentration
 Ozone background            All                      Not upper or lower-case “PPB”, “PPM”, or “UG/M3”                         Issue message and stop                  Re-prompt
 concentration units
 Pollutant ID                All                      Not set to NO2 but MODELOPT includes PVMRM or OLM                        Issue message and stop                  N/A




                                                                                                 A-2
Invalid building parameter inputs.
      Parameter                Invalid response             AERSCREEN.INP                Prompts
 Downwash flag             Response is not upper or      Issue message and stop   Re-prompt
                           lower-case Y or N
 Building height           Negative or non-numeric       Issue message and stop   Re-prompt
 Maximum building          Negative or non-numeric       Issue message and stop   Re-prompt
 horizontal dimension
 Minimum building          Non-numeric, negative or      Issue message and stop   Re-prompt
 horizontal dimension      exceeds maximum
                           horizontal dimension
 Angle of maximum          Non-numeric, less than        Issue message and stop   Re-prompt
 horizontal dimension      zero or exceeds 179
 relative to North         degrees
 Angle of stack location   Non-numeric, less than        Issue message and stop   Re-prompt
 relative to North         zero or exceeds 360
                           degrees
 Distance from stack to    Negative or non-numeric       Issue message and stop   Re-prompt
 building center
 Use pre-existing          File does not exist           Issue message and stop   Re-prompt
 BPIPPRM input file        Processing flag in file       Issue message and stop   Issue message and stop
                           incorrectly set for
                           AERMOD or more than
                           one stack listed in file.




                                                       A-3
Invalid meteorological data inputs.
       Parameter               Invalid response           AERSCREEN.INP                    Prompts
 Minimum Temperature      Non-numeric, negative (if    Issue message and stop      Re-prompt for
 Maximum Temperature      Kelvin), or minimum                                      temperatures
                          temperature is equal to or
                          exceeds maximum
                          temperature
 Minimum wind speed       Negative or non-numeric      Issue message and stop      Re-prompt
 Anemometer height        Negative or non-numeric      Issue message and stop      Re-prompt
 Surface code             Non-numeric, negative or     Issue message and stop      Re-prompt
                          greater than 9
 Climatology code         Non-numeric, less than       Issue message and stop      Re-prompt
                          1or exceeds 4 if surface
                          code between 1 and 8
                          inclusive
 User albedo              Non-numeric, negative, or    Issue message and stop if   Re-prompt
                          exceeds 1.0                  non-numeric.
                                                       Issue message and stop if
                                                       negative or exceeds 1.0
                                                       and surface code is 0
 User Bowen Ratio         Non-numeric                  Issue message and stop if   Re-prompt
                                                       non-numeric.
 User surface roughness   Negative or non-numeric      Issue message and stop if   Re-prompt
                                                       non-numeric.
                                                       Issue message and stop if
                                                       negative and surface code
                                                       is 0
 AERSURFACE output        Does not exist (if surface   Issue message and stop      Re-prompt for surface
 file                     code = 9)                                                characteristics type
                          Surface characteristics      Issue message and stop if   Issue message and re-
                          non-numeric, albedo is       surface code is 9           prompt for surface
                          negative or exceeds 1.0 or                               characteristics type
                          surface roughness is
                          negative
 Adjust u*                Response is not upper or     Issue message and stop      Re-prompt
                          lower-case Y or N




                                                    A-4
Invalid terrain data inputs.
      Parameter                   Invalid response                 AERSCREEN.INP                   Prompts
 Terrain flag             Response is not upper or lower-      Issue message and stop       Re-prompt
                          case Y or N
 Latitude                 Absolute value exceeds 90            N/A                          Re-prompt
                          degrees
 Longitude                Absolute value exceeds 180           N/A                          Re-prompt
                          degrees
 UTM Easting              N/A                                  N/A                          N/A
 UTM Northing             N/A                                  N/A                          N/A
 UTM zone                 Negative                             Issue message and stop       Re-prompt
 NAD code                 Not equal to 1 or 4                  Issue message and stop       Re-prompt
 Probe distance           Negative or less than minimum        Issue message and stop       Re-prompt for probe
                          ambient distance                                                  distance and minimum
                                                                                            ambient distance
 Discrete receptor        Response is not upper or lower-      Issue message and stop       Re-prompt
 flag                     case Y or N
 Discrete receptor file   File does not exist                  Issue message and stop       Re-prompt
                          The number of distances exceeds      Issue message and stop       Re-prompt
                          ten or negative distances found
                          Units line not included in file      Issue message and stop       Re-prompt
 Flagpole receptor        Response is not upper or lower-      Issue message and stop       Re-prompt
 use flag                 case Y or N
 Flagpole height          Negative or non-numeric              Issue message and stop (if   Re-prompt
                                                               flagpole receptors used)
 Source elevation         N/A                                  N/A                          N/A
 AERMAP use flag          Response is not upper or lower-      Issue message and stop       Re-prompt
                          case Y or N
 Demlist.txt              File is not in current folder        Issue message and stop       Issue message and stop
 NADGRIDS                 No grid files are in directory or    Issue message and stop       Issue message and stop
 directory or folder      folder or NADGRIDS keyword
                          not listed in demlist.txt



Invalid fumigation inputs.
 Parameter                Invalid response                     AERSCREEN.INP                Prompts
 Inversion break-up       Response is not upper or lower-      Issue message and stop       Re-prompt
 fumigation flag          case Y or N
 Shoreline                Response is not upper or lower-      Issue message and stop       Re-prompt
 fumigation flag          case Y or N
 Distance to              Distance is greater than 3 km or     Issue message and stop       Re-prompt
 shoreline                less than 0 km
 Direction from           Direction greater than 360 or        Issue message and stop       Re-prompt
 source to shoreline      less than 0 but not equal to -9
 Run AERSCREEN            Response is not upper or lower-      Issue message and stop       Re-prompt
 flag                     case Y or N; or if no fumigation
                          requested response is not upper
                          or lower-case Y


                                                         A-5
A-6
United States              Office of Air Quality Planning and Standards   Publication No. EPA-454/B-21-005
Environmental Protection         Air Quality Assessment Division                                 April 2021
Agency                             Research Triangle Park, NC
