AERSCREEN:

Status and Update

James Thurman

9th Modeling Conference

U.S. EPA/OAQPS/AQAD/AQMG

thurman.james@epa.gov
Overview

• AERSCREEN workgroup• Description and Features• Initial test results• MAKEMET• AERSCREEN stages• Questions
AERSCREEN Finalization Work

• Jim Haywood, Chair, Michigan DEQ• Karen Wesson, EPA• Roger Brode, EPA (formerly with MA• James Thurman, EPA• Bob Paine, ENSR• Lloyd Schulman, TRC• Acknowledge Herman Wong, EPA Re

10
AERSCREEN: Descripti

• AERSCREEN is a DOS tool that runs AE

in a “screening” mode for a single source

– calls MAKEMET, BPIPPRM and AERMAP to 

generate necessary AERMOD inputs

• Spring 2008, incorporates output from AERSURFA

does not currently call AERSURFACE

– SCREEN option added to AERMOD in 1995 

model to calculate centerline concentration fo

source/receptor/meteorology combination

• Output limited to to 1-hour averages and NOCHKD 

option to eliminate date sequence checking
AERSCREEN Features

• Program developed by Jim Haywood, MI DEQ

– Data entered via prompts or by input file– Source types: point, volume, rectangular area, circula

flare

– Flat or complex terrain

• AERSCREEN calls AERMAP for complex terrain proces• Terrain not used for rectangular area sources

– PRIME building downwash

• Specify stack location and direction relative to building c• Specify building dimensions (height, horizontal dimensio• Direction of long building dimension from north• Not used for area or volume sources• AERSCREEN calls BPIPPRM

– No deposition– MAKEMET meteorology

• Specify min and max temperatures, minimum wind spee

anemometer height and surface characteristics

• Internal matrices of other meteorological parameters
AERSCREEN Features

• User can specify

– Probe distance for terrain processing

• Default of 5 km for flat terrain (with or without build

downwash) or rectangular area sources

– Flagpole receptors– Elevation of source location for PROFBASE (

flat terrain) 

• Elevation above sea level for potential temperature 

– Rural or urban (if urban, urban population)– Ambient air distance (fence line distance)– Source location in geographic or UTM coordi

• Search routine to find worst case impact

– RANKFILE output in AERMOD– Concentration, date, direction, distance, and 

meteorology
AERSCREEN Features

• Routine to find maximum concentration fo

automatic receptor distances

• Re-Use of Previous AERSCREEN Run F• Performs errors checks on AERMOD and 

AERMAP output and writes log file of AERSCREEN run

• Includes factors for 3-hour, 8-hour, 24-ho

annual averages – based on upper bound SCREEN3 factors

– 3-hour: 1.0 (0.90 

±0.10)

– 8-hour: 0.9 (0.70 

± 0.20)

– 24-hour: 0.6 (0.40 

± 0.20)

– Annual: 0.1 (0.08 

± 0.02)
Figure 1: AERSCREEN Averaging Period Ratios vs. Plume 

(line shows 95th-percentile and error bars show 90th and 98th perc

0.00.10.20.30.40.50.60.70.80.91.0

0 50 100 150 

Plume height (m)
AERSCREEN Tests

• Significant testing to date shows goo

results across wide range of applica

• “Good” defined as reasonable 

conservatism compared to AERMOD refined estimates
168 2.98 0.

Flat Terrain

Non-downwash

Rural & Urban

Roger Brode

Bob Paine Complex Terrain 28 7.46 1.

168 4.56 0.

Complex Terrain

Varying Source/

Terrain Distance

Roger Brode

Karen Wesson Stack non-downwash 26 2.18 0.

Karen Wesson Stack downwash 32 2.54 0.

Jim Haywood Miscellaneous 7 5.20 1.

M

Ra

Max. 

Ratio

No. of 

sources

Database Type
MAKEMET

• MAKEMET loops through several meteorologica

parameters:

– Wind speed (stable and convective)– Cloud cover (stable and convective)– Max/min ambient temp (stable and convective) – Solar elevation angle (stable and convective)– Convective velocity scale (w*) (convective only)– Mechanical mixing heights (stable only)

• Uses AERMET subroutines to calculate u* and L

also calculates convective mixing heights

• For AERSCREEN, uses wind direction of 270• Generates surface and profile files for running A
Surface Characteristics and MAK

• Three methods of surface characteristics into 

AERSCREEN

1. User defined: annual, non-sector based 2. Seasonal tables from AERMET User’s Guide (Tables 

• User specifies dominant land use type and moisture con

– Water, deciduous forest, coniferous forest, swamp, cultiva

grassland, urban, desert shrubland

– Moisture for Bowen ratio: average, dry, or wet

• Non-sector based

3. AERSURFACE output

• User enters AERSURFACE output filename or AERMET 

filename

• Annual, seasonal, or monthly • 1 to 12 surface roughness sectors sectors• AERSURFACE is run for the source location

• MAKEMET is run for each temporal, sector com

and met files generated for each combination
Input and validate data

Generate meteorological files and run BPIPPRM and AERMAP for s

necessary

Is there a source-receptor

direction

dependency?

flat terrain and no downwash and not a rectangular area source, execute PROBE

terrain and/or dowrectangular area sFLOWSECTOR

REFINE

Output

User actions

Program actions

No Yes

AERSCREEN Stages & St
Example input file
Validation 

page
Summary of stages

• PROBE

– 5 km default probe distance (25 m spacing) in one directi– AERMOD executed for each temporal/spatial sector of S

• FLOWSECTOR

– Rectangular area sources

• 5 km probe distance (25 m spacing) for 5 degree diagonals• AERMOD run for each SC temporal/spatial sector for each 

– Other sources

• Receptors every 10 degrees out to probe distance• Direction specific terrain and projected building dimensions • AERMOD run for each SC temporal sector

– Upwind spatial sector of direction being processed

• REFINE

– Find overall maximum concentration from PROBE or FLO– Use meteorology and SC associated with maximum conc– If terrain and/or downwash, use terrain heights and proje

dimensions of direction of maximum concentration

– Refine receptor spacing to 1, 2, or 5 m increments
5 km

PROBE

0

5

10

15

20

25

30

FLOWSECTOR: rectangula

FLOWSECTOR: other sources
-------------------------------------------------------------------

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

MAXIMUM SCALED SCALED SCALED 

1-HOUR 3-HOUR 8-HOUR 24-HOUR 

CALCULATION CONC CONC CONC CONC 

PROCEDURE (ug/m3) (ug/m3) (ug/m3) (ug/m3) 

--------------- ---------- ---------- ---------- ---------- ELEVATED TERRAIN 0.3652E+05 0.3652E+05 0.3287E+05 0.2191E+05 DISTANCE FROM SOURCE 139.0 meters directed toward 180 degreesRECEPTOR HEIGHT -5.02 metersIMPACT AT THEAMBIENT BOUNDARY 0.1552E+05 0.1552E+05 0.1397E+05 9310. DISTANCE FROM SOURCE 30.0 meters directed toward 110 degreesRECEPTOR HEIGHT -5.88 meters
Future

• Draft release package:

– AERSCREEN and MAKEMET executa– User can download BPIPPRM, AERMO

AERMAP and AERSURFACE from SC

website

http://www.epa.gov/scram001

– User documentation and example case