Roger W. BrodeU.S. EPA/OAQPS/AQADAir Quality Modeling Group

AERMOD Update:Status of AERSCREEN and AERSURFACE

EPA R/S/L Modelers WorkshopVirginia Beach, VirginiaMay 15, 2007

Presentation Outline

AERSCREEN Overview and Status

AERSURFACE Overview and Status

Questions

AERSCREEN Finalization Workgroup

Jim Haywood, Chair, Michigan

Karen Wesson, EPA

Roger Brode, EPA (formerly with MACTEC)

Bob Paine, ENSR

Lloyd Schulman, TRC

Acknowledge Herman Wong, EPA Region 10

What is AERSCREEN?

AERSCREEN refers to applying the AERMOD model in a “screening mode”

– 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 consists of two components– MAKEMET program generates matrix of meteorological conditions

based on user-specified surface characteristics, formatted for input to AERMOD (.sfc and .pfl files)

– ASCREEN program provides interface to run AERMOD in SCREEN mode, incorporates MAKEMET, BPIPPRM and AERMAP

Description of AERSCREEN

MAKEMET includes loops through 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, also calculates convective mixing heightsGenerates surface and profile files for running AERMOD in stand-alone mode

Description of AERSCREEN

ASCREEN command-prompt program developed by Jim Haywood, Michigan DEQ

– Interactive data entry (command prompts/DOS Screen)– Single point, volume or area source– Flat and Complex terrain (DEM 1-degree files (automatically)

or user-specified list of 7.5-minute DEM files)– PRIME building downwash (specify stack location)– MAKEMET meteorology with site-specific surface

characteristics– Search routine to locate worst-case impact location– Re-Use of Previous AERSCREEN Run Files– Includes source-dependent factors for 3-hour, 8-hour, 24-hour

and annual averages – similar to SCREEN3 factors

AERSCREEN Status

Draft AERSCREEN package submitted to EPA regions on 4/25/06 for internal (alpha) review and testing

Comments received from several regions and states; many comments related to problems with AERMAP

Public release of draft AERSCREEN package expected by summer 2007

AERSCREEN Status

ASCREEN program updated to use new AERMAP and AERMOD executables; AREA source addedAERMET NR_ANG bug fix needs to be incorporatedDefault surface characteristics may be modified for consistency with AERSURFACE; possible linkage with AERSURFACEPrevious testing to be updated with latest version; additional testing of AERSCREEN vs. on-site met data also plannedAdditional documentation, including draft user’s guide and test results, needed before public release

AERSCREEN Tests

Significant Testing to Date Shows Good Results Across Wide Range of Applications“Good” Defined as Reasonable Conservatism Compared to AERMOD Refined EstimatesTesting Performed for Rugged Terrain Applications with Downwash – Minor Modifications to MAKEMET

1.050.982.98168Flat Terrain

Non-downwashRural & Urban

Roger Brode

2.231.087.4628Complex TerrainBob Paine

1.180.964.56168Complex TerrainVarying Source/Terrain Distance

Roger Brode

1.490.972.1826Stack non-downwashKaren Wesson

1.170.962.5432Stack downwashKaren Wesson

2.351.095.207MiscellaneousJim Haywood

MedianRatio

Min. Ratio

Max. Ratio

No. of sources

TypeDatabase

ISC-AERMOD View - Lakes Environmental Software D:\Projects\G_Projects\G168-BC\BCASCR50.isc

PROJECT TITLE:

British Columbia AERSCREEN TestsSource Group Locations

PROJECT NO.:

SCALE:

0 10 km

1:476,448

COMMENTS:

MODELER:

COMPANY NAME:SOURCES:

7

RECEPTORS:

0

metersTerrain Contours

0.0 5.0 10.0 20.0 50.0 100.0 200.0 300.0 500.0 800.0 1200.0 1800.0 2400.0

0

0

0

0

0

0

0

0

0

5

5

5

5

5

5

5

5

5

5

5

5

5

5

55

5

5

5

10

10

10

10 10

10

10

10

10

10

10

1010

10

10 10

10

10

10

10

10

10

10

20

20

20

20

20

20

20

20

20

20

20

20

20

20

20

20

20

20

20

20

50

50

50 50

50

50

50

50

50

50

50

50

50

50

50

50

50

50

50

50

100

100

100

100

100

100

100 10

0

100

100

100

100

100 200

200

200

200

200

200

200

200

200

200

200

300

300

300

300

300

300

300

300

300

300

300

300

300

500

500

500

500

500

500

500

500

500

500

500

500

500

500

500

500

500

800

800

800

800

800

800

800

800800

800

800

800

800

800

800

800

00

800

800

800

1200

1200

1200

1200

1200

S7

S6

S5

S4S3

S2

S1

470000 480000 490000 500000 510000 520000 530000 540000

5440

000

5450

000

5460

000

5470

000

5480

000

5490

000

Table 5.2b: Highest 1-hour Screening vs. Refined Results for SeaTac Airport Surface Characteristics

Source Location Source ID

Screening χ/Q

Screening Elevation (m MSL)

Screening Hill Height Scale

(m MSL) Refined χ/Q

Refined Elevation (m MSL)

Refined Hill Height Scale

(m MSL) Screening/

Refined Ratio S1 S1_LG 1.809 172 343 1.215 172 343 1.490 S1 S1_MD 11.063 7 7 9.610 7 7 1.151 S1 S1_SM1 1039.690 8 8 982.543 7 7 1.058 S1 S1_S10 637.866 7 7 354.042 8 8 1.802 S1 S1_SM2 357.879 7 7 343.719 7 7 1.041 S1 S1_S08 157.525 7 7 153.008 7 7 1.030 S2 S2_LG 22.772 183 203 20.287 183 203 1.122 S2 S2_MD 307.198 77 1178 226.239 82 1178 1.358 S2 S2_SM1 906.567 31 1178 905.019 31 1178 1.002 S2 S2_S10 1162.820 34 1178 829.149 39 1178 1.402 S2 S2_SM2 420.120 30 1178 397.065 29 1178 1.058 S2 S2_S08 399.932 49 1178 329.575 52 1178 1.213 S3 S3_LG 38.410 187 1178 24.717 193 1499 1.554 S3 S3_MD 257.356 78 1178 163.786 85 1178 1.571 S3 S3_SM1 6047.862 37 1178 1768.820 40 1178 3.419 S3 S3_S10 6047.862 37 1178 4662.883 39 1178 1.297 S3 S3_SM2 847.681 44 1178 882.339 44 1178 0.961 S3 S3_S08 599.342 49 1178 506.168 49 1178 1.184 S4 S4_LG 16.585 363 1178 12.337 366 1009 1.344 S4 S4_MD 79.196 254 1009 55.373 260 1009 1.430 S4 S4_SM1 1069.212 204 1009 1010.431 204 1009 1.058 S4 S4_S10 775.393 210 1009 615.640 215 1009 1.259 S4 S4_SM2 360.180 202 1009 330.230 201 1009 1.091 S4 S4_S08 155.487 202 1009 150.366 202 1009 1.034 S5 S5_LG 1.104 164 343 0.712 173 1009 1.551 S5 S5_MD 11.093 4 4 9.556 1 1 1.161 S5 S5_SM1 1068.335 4 4 988.166 3 3 1.081 S5 S5_S10 636.110 2 6 341.107 4 4 1.865 S5 S5_SM2 359.929 2 2 328.516 1 1 1.096 S5 S5_S08 155.917 2 3 151.804 2 2 1.027 S6 S6_LG 14.187 213 343 8.273 213 343 1.715 S6 S6_MD 143.747 108 108 83.777 118 202 1.716 S6 S6_SM1 5843.050 66 1178 3262.436 69 1178 1.791 S6 S6_S10 5843.050 66 1178 4850.776 69 1178 1.205 S6 S6_SM2 1294.519 76 1178 1065.870 76 1178 1.215 S6 S6_S08 644.158 65 1178 605.457 65 1178 1.064 S7 S7_LG 38.269 257 417 25.531 262 309 1.499 S7 S7_MD 597.878 146 417 377.833 152 417 1.582 S7 S7_SM1 5843.050 103 417 1276.771 104 417 4.576 S7 S7_S10 5843.050 103 417 4891.969 106 417 1.194 S7 S7_SM2 2130.484 112 417 2019.556 113 417 1.055 S7 S7_S08 976.258 117 417 851.028 117 417 1.147

Averaging Factors

3-hour: fixed ratio of 0.95 (SCREEN3 – 0.90 ± 0.10);8-hour: fixed ratio of 0.70 (SCREEN3 – 0.70 ± 0.20);24-hour : fixed ratio of 0.40 for plume heights up to 100m, then linearly interpolated to a ratio of 0.30 for plume heights above 200m (SCREEN3 – 0.40 ± 0.20)Annual: fixed ratio of 0.10 for plume heights up to 100m, then linearly interpolated to a ratio of 0.04 for plume heights above 200m (SCREEN3 – 0.08 ±0.02).

Figure 1: AERSCREEN Averaging Period Ratios vs. Plume Height(line shows 95th-percentile and error bars show 90th and 98th percentiles)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0 50 100 150 200

3-hr8-hr24-hrAnnual

SCREEN 3-hr

SCREEN 8-hr

SCREEN 24-hr

SCREEN Ann

Topics for Discussion

Results from testingExperiences with ASCREEN versus operating AERMOD with MAKEMET aloneAveraging factors: Results? Fixed vs varying?Multiple source screening? MAKEMET and “site-specific” minimum wind speed and anemometer height? Defaults?Building downwash and dependency on direction-specific building dimensions.

What is AERSURFACE?

AERSURFACE is a tool that produces surface characteristics data (albedo, Bowen ratio & surface roughness) for use in AERMET and/or AERSCREENOriginal program developed by Chris Arrington (WV DEP) and Larry Simmons (Energy & Environmental Management, Inc.)New version being developed by EPA with contractor support (MACTEC)

AERSURFACE Description

EPA AERSURFACE program currently uses USGS NLCD 92 data– 21-category land cover classification scheme– 30 m spatial resolution– Currently supports State files

AERSURFACE includes updated tables of seasonal variations for surface characteristics data by land use category

NLCD Land Use CategoriesTable 1: USGS NLCD 92 Land Use Categories Classification Class Land Use Category

Open Water Water Perennial Ice/Snow Low Intensity Residential High Intensity Residential

Developed

Commercial/Industrial/TransportationBare Rock/Sand/Clay Quarries/Strip Mines/Gravel Pits

Barren

Transitional Deciduous Forest Evergreen Forest

Forested Upland

Mixed Forest Shrubland Shrubland Non-natural Woody Orchards/Vineyards/Other Herbaceous Upland Grasslands/Herbaceous

Pasture/Hay Row Crops Small Grains Fallow

Herbaceous Planted/Cultivated

Urban/Recreational Grasses Woody Wetlands Wetlands

Emergent Herbaceous Wetlands

AERSURFACE Surface CharacteristicsA-3. Seasonal Values of Surface Roughness for the NLCD 92 21-Land Use Classification System

Seasonal Surface Roughness1 (m) s ber Class Name

1 2 3 4 5 Reference

11 Open Water 0.001 0.001 0.001 0.001 0.001 Stull2

12 Perennial Ice/Snow 0.002 0.002 0.002 0.002 0.002 Stull2 21 Low Intensity Residential 0.77 0.77 0.65 0.63 0.72 (22+43+85)/33

22 High Intensity Residential 1 1 1 1 1 AERMET 4

Commercial/Industrial/Transp (Site at Airport) 0.1 0.1 0.1 0.1 0.1 5%: 22 & 95%: 315 23

Commercial/Industrial/Transp (Not at Airport) 0.8 0.8 0.8 0.8 0.8 80%: 22 & 20%: 315 Bare Rock/Sand/Clay (Arid Region) 0.05 0.05 0.05 NA 0.05 Slade6 31 Bare Rock/Sand/Clay (Non-arid Region) 0.05 0.05 0.05 0.05 0.05 Slade6

32 Quarries/Strip Mines/Gravel 0.3 0.3 0.3 0.3 0.3 Estimate7 33 Transitional 0.2 0.2 0.2 0.2 0.2 Estimate8 41 Deciduous Forest 1.3 1.3 0.6 0.5 1 AERMET 4 42 Evergreen Forest 1.3 1.3 1.3 1.3 1.3 AERMET 4 43 Mixed Forest 1.3 1.3 0.95 0.9 1.15 (41+42)/2 9

Shrubland (Arid Region) 0.15 0.15 0.15 NA 0.15 50% 51 (Non-Arid)10 51 Shrubland (Non-arid Region) 0.3 0.3 0.3 0.15 0.3 AERMET 4

61 Orchards/Vineyards/Other 0.3 0.3 0.1 0.05 0.2 Garratt11 71 Grasslands/Herbaceous 0.1 0.1 0.01 0.005 0.05 AERMET 4 81 Pasture/Hay 0.15 0.15 0.02 0.01 0.03 Garratt11 & Slade12 82 Row Crops 0.2 0.2 0.02 0.01 0.03 Garratt11 & Slade12 83 Small Grains 0.15 0.15 0.02 0.01 0.03 Garratt11 & Slade12 84 Fallow 0.05 0.05 0.02 0.01 0.02 31 & 81,82,8313 85 Urban/Recreational Grasses 0.02 0.015 0.01 0.005 0.015 Randerson14 91 Woody Wetlands 0.7 0.7 0.6 0.5 0.7 (43+92)/215 92 Emergent Herbaceous Wetlands 0.2 0.2 0.2 0.1 0.2 AERMET 4

AERSURFACE Status

Draft AERSURFACE design document submitted to RO’s for review July 2006Comments received from Regions and States, especially regarding draft look-up tablesDraft version of AERSURFACE for RO review expected by end of May 2007, including updated tables of surface characteristics

AERSURFACE Status

Recent revision to calculating area-weighted averages for surface characteristics:– Incorporated inverse-distance-squared weighting to

account for increased width/area of sector with distance

Additional options for calculating “effective”surface characteristics may still be explored:– “Blending height” concept for roughness– Geometric mean or “harmonic-like” average for

Bowen ratio

Draft AERSURFACE Design

There will be default values/functions but users will be given choices:– Number of sectors (up to 12)– Radius used to evaluate land use data– Output monthly, seasonal, annual data– Wet/dry/normal conditions for Bowen ratio– Snow vs. no snow cover– Arid vs. Non-arid– Airport vs. Non-airport location

Applying AERSURFACE

USGS NLCD 92: Example data

USGS NLCD 92: Example data

AERMET Input from AERSURFACE

FREQ_SECT ANNUAL 12SECTOR 01 000 030SECTOR 02 030 060SECTOR 03 060 090SECTOR 04 090 120SECTOR 05 120 150SECTOR 06 150 180SECTOR 07 180 210SECTOR 08 210 240SECTOR 09 240 270SECTOR 10 270 300SECTOR 11 300 330SECTOR 12 330 360SITE_CHAR 1 01 0.11 0.89 0.7122SITE_CHAR 1 02 0.10 0.97 0.9448SITE_CHAR 1 03 0.10 0.94 0.9267SITE_CHAR 1 04 0.11 0.89 0.7482SITE_CHAR 1 05 0.11 0.94 0.7436SITE_CHAR 1 06 0.10 0.99 0.9336SITE_CHAR 1 07 0.10 0.99 0.9313SITE_CHAR 1 08 0.10 0.97 0.8699SITE_CHAR 1 09 0.10 0.97 0.8888SITE_CHAR 1 10 0.10 0.94 0.8399SITE_CHAR 1 11 0.10 0.97 0.9241SITE_CHAR 1 12 0.11 0.58 0.5064

AERMOD Sensitivity Analysis

Varied Surface Characteristics:– Albedo Test: α=0.1-0.6 (Bo=1.0, zo=0.1)– Bowen Ratio Test: Bo=0.1-10 (α=0.2, zo=0.1)– Surface Roughness Test: zo=0.001-1.3m

(α=0.2, Bo=1.0)

Varied Stack Heights and Buoyancy– 5,10,15,20,25,30,50,75,100,150,200m non-buoyant

– 100,150,200m very buoyant (VB)

AERMOD Sensitivity Analysis

Two meteorology sites:– Pittsburgh– Oklahoma City

Rural and Urban (population=2.4 million)24-hr and Annual averages

AERMOD Sensitivity Analysis

Changes in albedo and Bowen ratio affect convective turbulence– ↓ Albedo ↑ Convective turbulence– ↑ Bowen ratio ↑ Convective turbulence

Changes in surface roughness affect mechanical turbulence– ↑ Surface roughness ↑ Mechanical turbulence

Albedo – Normalized Percent Differences

Bowen Ratio – Normalized Percent Differences

Surface Roughness – Normalized Percent Differences

Sensitivity Analysis Conclusions

AERMOD is most sensitive to changes in zo for low-level releases

– This is due to the impact of changes in zo on mechanical turbulence:↑ Surface roughness will ↑ Mechanical turbulence

Some sensitivity to changes in albedo and Bowen ratio, especially for taller, more buoyant stacks– Lower albedo or higher Bowen ratio will increase

convective turbulence and bring plume down quicker

Questions