Meteorological Data for Dispersion 

Models

11th Modeling Conference

Research Triangle Park, NC

August 12, 2015

Chris Misenis and James Thurman

U.S. EPA/OAQPS/AQAD/AQMG

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Meteorological data workgroup

• James Thurman (OAQPS)

• Chris Misenis (OAQPS)

• George Bridgers (OAQPS)

• Roger Brode (OAQPS)

• Randy Robinson (Region 5)

• Andy Hawkins (Region 7)

• Rebecca Matichuk (Region 8)

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Acknowledgments

• Kali Frost (Indiana Department of Environmental 

Management)

– Provided Gibson AERMOD inputs and observations for 

MMIF evaluations

• Missouri Department of Natural Resources, Andy 

Hawkins, R7

– Herculaneum inputs

• Andy Hawkins, Kirk Baker (OAPQS), Roger Brode 

– Martins Creek WRF/MMIF output

• Rebecca Matichuk, R8

– Meteorological analysis of sites in R8

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Meteorological data in the proposed Guideline 

Section 8.4

• AERMINUTE 

– Introduced in 2011

– Calculates hourly average of winds from 2-minute winds for ASOS stations

– March 2013 memorandum issued regarding use of ASOS data and 

AERMINUTE in AERMOD

• http://www.epa.gov/ttn/scram/guidance/clarification/20130308_Met_Data_Clarification.pdf

– Should be routinely used when available

• Prognostic meteorological data

– No representative NWS station and infeasible to collect site-specific data

– No fewer than 3-years of data

– Mesoscale Model Interface Program (MMIF) developed to read prognostic 

data (i.e., WRF) to create data for input into AERMET and AERMOD, as 

well as other dispersion models

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Prognostic Meteorological Data

Guidance

• Number of years: Minimum of 3 years

• Follow Ozone, PM2.5, and Regional Haze 

modeling guidance for developing 

meteorological fields1

• Evaluation procedures

• Link:

– http://www.epa.gov/ttn/scram/11thmodconf/Draft_MMIF_Guidance.pdf

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1. http://www.epa.gov/ttn/scram/guidance/guide/Draft_O3-PM-RH_Modeling_Guidance-2014.pdf
Prognostic Meteorological Data Guidance

• Guidance for running MMIF for AERMOD

– Regulatory applications: MMIF to AERMET

• AERMET regulatory meteorological pre-processor for AERMOD

• Take advantage of options in AERMET (u* adjustment)

– All others: MMIF to AERMET or MMIF to AERMOD

• Grid resolution

– Dependent upon location (complex terrain; complex 

meteorology)

• Representative grid cell

– Most cases, grid cell of facility of interest

• Other recommendations

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http://www.epa.gov/ttn/scram/11thmodconf/MMIF_Evaluation_TSD.pdf

Prognostic Data Evaluation

• Three case studies

– Gibson, IN (SO2)

– Martins Creek, PA (SO2)

– Herculaneum, MO (Pb)

• Meteorological evaluations

• AERMOD evaluations 

(EPA protocol for 

determining best 

performing model)

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7/30/2015 U.S. Environmental Protection Agency 8

Gibson

Evansville

Gibson study meteorological data 

locations

WRF 12 km cells
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Model Comparison Measure (MCM) Gibson (95th percentile CI)

2nd scenario performs better 1st scenario performs better

EVV MMIF: Evansville WRF cell

EVV OBS: Evansville NWS obs

GIB MMIF: Facility WRF cell

GIB OBS: Facility site-specific obs
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ABE

Martins Creek 

(meteorology)

WRF 1 KM

WRF 4 KM

Martins Creek (emissions)

Hoffman-LaRoche

Portland

Warren

Monitors

Martins Creek study meteorological data 

locations
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Model Comparison Measure (MCM) Martins Creek (95th percentile CI)

2nd scenario performs better 1st scenario performs better

ABE: Allentown NWS obs

Martins Creek: Martins Creek obs

MMIF 1 km: WRF 1 km

MMIF 4 km: WRF 4 km
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MMIF 36 KM

CPS

MMIF 12 KM

MMIF 4 KM

Herculaneum

Doe Run

Monitors

Herculaneum study meteorological data 

locations
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24-hour screen

Herculaneum

Biases based on top 25 concentrations

WRF outside 

factor of 2 box 

but comparable 

to site-specific 

data

CPS: St. Louis NWS obs

Herculaneum: Herculaneum obs

MMIF 4 km: WRF 4 km

MMIF 12 km: WRF 12 km

MMIF 36 km: WRF 36 km
Summary

• Gibson

– Prognostic data not statistically different from 

observed data

• Martins Creek

– Prognostic data statistically different from sitespecific data; not statistically different from NWS 

data

• Herculaneum

– Screening analysis indicated prognostic data 

performance comparable to site-specific data

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Links

• Draft Guidance on use of MMIF in AERMOD

– http://www.epa.gov/ttn/scram/11thmodconf/Draft_MMIF_Guidance.pdf

• Evaluation of Prognostic Meteorological Data 

in AERMOD

– http://www.epa.gov/ttn/scram/11thmodconf/MMIF_Evaluation_TSD.pdf

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