1. AERSCREEN Status and Update James Thurman, Ph.D. U.S. EPA/OAQPS/AQAD Air Quality Modeling Group 2009 NESCAUM PMC Annual Meeting Mystic, CT

2. AERSCREEN Finalization Workgroup Jim Haywood, Chair, Michigan DEQ Karen Wesson, EPA Roger Brode, EPA James Thurman, EPA Bob Paine, ENSR Lloyd Schulman, TRC Acknowledge Herman Wong, EPA Region 10

3. AERSCREEN: Description AERSCREEN is a tool that runs AERMOD in a “screening” mode for a single source –SCREEN option added to AERMOD in 1995 forces model to calculate centerline concentration for each source/receptor/meteorology combination –SCREEN option limits output to 1-hour averages and selects NOCHKD option to eliminate date sequence checking –AERSCREEN program provides DOS interface to run AERMOD in SCREEN mode including calls to MAKEMET, BPIPPRM and AERMAP to generate necessary AERMOD inputs Spring 2008, incorporates output from AERSURFACE but does not currently call/run AERSURFACE Spring 2009, updated to incorporate new features in AERMAP –NED elevation data –Location of grid files for NAD conversion

4. AERSCREEN Regulatory Status “With respect to a screening version of AERMOD, a tool called AERSCREEN is being developed with a beta version expected to be publicly available in Fall 2005. SCREEN3 is the current screening model in the Guideline, and since SCREEN3 has been successfully applied for a number of years, we believe that SCREEN3 produces an acceptable degree of conservatism for regulatory applications and may be used until AERSCREEN or a similar technique becomes available and tested for general application. “ Appendix W Preamble Part IV, Section C, paragraph 7 pg. 68221

5. AERSCREEN Features Program developed by Jim Haywood, MI DEQ –Data entered via prompts or by input file English or metric units via prompts, metric for input file –Source types: point, volume, rectangular area, circular area, and flare June 2009: added capped and horizontal stacks –Flat or complex terrain –PRIME building downwash –No deposition or polygon sources (AREAPOLY) –MAKEMET meteorology

6. AERSCREEN Features User can specify –Probe distance (maximum distance of downwind receptors) –Flagpole receptors –Elevation of location for PROFBASE (even for flat terrain) Elevation above sea level for potential temperature profile –Rural or urban (if urban, urban population) –Ambient air distance (fence line distance) Search routine to find worst case impact

7. AERSCREEN Features Re-Use of Previous AERSCREEN Run Files (AERSCREEN.INP) Performs errors checks on AERMOD and AERMAP output and writes log file of AERSCREEN run Includes factors for 3-hour, 8-hour, 24-hour and annual averages – based on upper bound of SCREEN3 factors –3-hour: 1.0 –8-hour: 0.9 –24-hour:0.6 –Annual: 0.1

8. AERSCREEN Tests Significant testing to date shows good results across wide range of applications “Good” defined as reasonable conservatism compared to AERMOD refined estimates

9. AERSCREEN Source Inputs Vertical (no cap) stack (POINT), capped (POINTCAP), or horizontal (POINTHOR) stacks –Emission rate (g/s or lb/hr) –Stack parameters: height, inner diameter, exit temperature, exit velocity or flow rate Flare (POINT) –Emission rate (g/s or lb/hr) –Stack height, total heat release rate, radiative heat loss fraction (option to input value or use default SCREEN3 value, 0.55) –Diameter and effective stack height calculated from inputs

10. AERSCREEN Source Inputs Volume (VOLUME) –Emission rate (g/s or lb/hr) –Release height (center of volume), initial lateral and vertical dimensions of volume Area sources (AREA or AREACIRC) –Emission rate (g/s or lb/hr) –Release height above ground –Initial vertical dimension of plume –Long (xinit) and short (yinit) sides’ lengths of rectangular area (AREA) –Radius of circular area (AREACIRC) –Rectangular source is assumed to have orientation angle of 0 –Area source optimization option used in AERMOD

11. Building Downwash Inputs Maximum and minimum horizontal building dimensions Building height Orientation of maximum building dimension to North Orientation of stack relative to building center (degrees from North) Distance between building center and stack AERSCREEN will calculate necessary inputs and run BPIPPRM

12. N Height Max length Min length Stack to building center distance Angle of stack to building center Building orientation = 0 deg. to North

13. Building orientation of 90 deg. to north Stack 30 deg. from north x y x y N 30 min dim max dim sdistance stack Building orientation of 20 deg. to north Stack 30 deg. from north N 30 min dim Max dim sdistance 20 stack

14. Terrain inputs Coordinates of source –Prompts: geographic or UTM If geographic, AERSCREEN converts to UTM for input to AERMAP –Input file: UTM, NAD83 UTM zone –If user enters geographic coordinates, calculated by AERSCREEN NAD 27 or 83 –AERSCREEN converts coordinates to UTM NAD 83 Probe distance (km) –Default of 5 km for FLAT terrain, 10 km for non-FLAT terrain

15. Terrain inputs Source elevation or allow AERSCREEN to use AERMAP to calculate (non FLAT only) DEM or NED elevation filename listed in a user- created file called demlist.txt Demlist.txt can also contain the location of the grid files needed for NAD conversion. –Must be named demlist.txt

16. NED : Must be either DEM or NED ---------------------------------------------------- NADGRIDS grids\ NED_35703440.tif Sample DEMLIST.TXT Tells AERSCREEN what form of data for DATATYPE keyword in AERMAP Location of NAD grid conversion files, i.e., conus.las conus.los for NADGRIDS keyword in AERMAP * If keyword missing, files are assumed to be in working folder Elevation file(s). If more than one file used, one file per line listed. * If NADGRIDS path or elevation file path contains spaces, must enclose in quotes

17. MAKEMET MAKEMET loops through several meteorological 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, and also calculates convective mixing heights Generates surface and profile files for running AERMOD in stand-alone mode

18. MAKEMET inputs Minimum and maximum temperature –Average calculated by AERSCREEN Minimum wind speed –Default of 0.5 m/s –Minimum is 0.5 m/s Anemometer height –Default 10 m Surface characteristics

19. Surface Characteristics and MAKEMET Three methods of inputting surface characteristics into AERSCREEN –User defined: non-sector based –Seasonal tables from AERMET User specifies dominant land use type and moisture conditions (average, dry, or wet) Non-sector based –AERSURFACE output User enters AERSURFACE output filename or AERMET stage 3 input filename Annual, seasonal, or monthly 1 to 12 sectors AERSURFACE is run for the source location by user

20. Surface Characteristics and MAKEMET MAKEMET is run for each temporal, sector combination and met files generated for each combination –User defined SC: 1 set of files –Seasonal tables: 4 sets of files –AERSURFACE: 1 (annual/1 sector) to 144 (monthly/12 sectors) sets of files

21. AERSCREEN Steps Input and validate data NO (flat terrain and no downwash and not a rectangular area source) PROBE FLOWSECTOR Generate meteorological files YES (terrain and/or downwash or rectangular area source) REFINE Output REFINE Output Is there a source-receptor direction dependency? User actions Model actions Run BPIPPRM if downwash

22. Example input file

23. Validation page

24. Source parameter options

25. PROBE Executed for non-rectangular area sources, flat terrain, and no building downwash (no direction dependency) Receptors placed out to user-specified probe distance –200 receptors or 25 m spacing (if spacing < 25 m) AERMOD is executed for each combination of temporal and sector resolution of surface characteristics –i.e. 4 seasons and 2 surface sectors=8 AERMOD runs

26. Source receptor orientation for PROBE Source

27. FLOWSECTOR: Rectangular Area Sources Receptors placed from fence line out to user- specified probe distance on 5 degree diagonals –Every 25 m or 200 receptors AERMOD executed for each temporal step and surface roughness sector for each diagonal –Westerly wind direction rotated by angle of diagonals in AERMOD (WDROTATE) –4 seasons x 2 sectors x 7 diagonals = 56 runs Area source optimization (FASTAREA) option used

28. Rectangular area source receptor orientation for FLOWSECTOR 5 deg. diagonal 0 deg. 10 deg. 15 deg. 20 deg. 25 deg. 30 deg. *diagonal is not used in receptor network 500 m 250 m

29. N Sector 1

30. N Sector 2

31. N Sector 3

32. FLOWSECTOR: Other sources Receptors placed along 10 degree radials from fence line out to probe distance –Every 25 m or 200 receptors out to probe distance If terrain used, FLOWSECTOR creates AERMAP input file and runs AERMAP –Terrain heights for direction being processed used If downwash, projected dimensions for direction being processed used The appropriate upwind sector for the processed flow vector is used for surface characteristics –4 seasons x 36 radials = 144 runs

33. 1 2 3

34. REFINE Find maximum concentration from PROBE or FLOWSECTOR Use meteorology associated with the maximum concentration and refine receptor spacing –1, 2, or 5 m spacing; dependent on downwind distance of maximum concentration If terrain used, AERMAP rerun to reflect new receptor locations in direction of maximum concentration If downwash used, use projected building dimensions associated with direction of maximum concentration

35. AERSCREEN OUTPUTS Output files –AERSCREEN.LOG Lists inputs, any warnings or errors during processing –AERSCREEN.OUT List inputs, intermediate outputs and final output –AUTOMATIC_DISTANCES.TXT Lists overall maximum 1-hour concentration by distance and associated meteorology –AERSCREEN.INP Output to screen –Overall maximum 1-hour concentration and distance from source Includes 3, 8, 24-hour, and annual scaled concentrations –1-hour concentration at fence line for same meteorology as overall maximum concentration –These are written to AERSCREEN.OUT as well

36. Next steps Prepare code for beta release –Additional code testing and compatibility with updated AERMOD –MAKEMET executable included in release package –AERMOD, AERMAP, and BPIPPRM available on SCRAM User’s guide

37. Contact James Thurman thurman.james@epa.gov (919) 541-2703

38. DEMONSTRATION