AERMOD ImplementationAERMOD Implementation

Alan J. Cimorelli8th Conference on Air Quality Modeling

Research Triangle Park, NCSeptember 22-23, 2005

OutlineOutline

Approach to AERMOD ImplementationApproach to AERMOD Implementation Guidance DevelopmentGuidance Development Implementation GuideImplementation Guide Model ImprovementsModel Improvements SummarySummary

AERMOD Implementation ProcessAERMOD Implementation Process

NEED: As implementation proceeds issues will NEED: As implementation proceeds issues will arise arise

PROCESS:PROCESS:– ISC or AERMOD for one year after promulgationISC or AERMOD for one year after promulgation– Provide Implementation Guide with promulgationProvide Implementation Guide with promulgation– Model Clearinghouse ProcessModel Clearinghouse Process

State contacts RegionState contacts Region Region writes memo to ClearinghouseRegion writes memo to Clearinghouse Clearinghouse memo back to RegionClearinghouse memo back to Region Archive memos / Annual reportArchive memos / Annual report As precedents and consensus builds, develop As precedents and consensus builds, develop

guidanceguidance– Model improvementsModel improvements

Guidance DevelopmentGuidance Development PURPOSE: Facilitate the scientifically appropriate & PURPOSE: Facilitate the scientifically appropriate &

consistent regulatory application of AERMODconsistent regulatory application of AERMOD Basic tenets:Basic tenets:

– Keep principle based - avoid overly prescriptive guidanceKeep principle based - avoid overly prescriptive guidance– Recognize the importance of initial decisions (precedence)Recognize the importance of initial decisions (precedence)– Allow flexibility for unique casesAllow flexibility for unique cases– Vet, document & rule-make where appropriateVet, document & rule-make where appropriate

Types of guidance:Types of guidance:– Appendix “W”Appendix “W”– EPA ReportEPA Report– OAQPS policy memosOAQPS policy memos– Clearinghouse memosClearinghouse memos– Individual precedentsIndividual precedents

Implementation GuideImplementation Guide Selecting Surface Characteristics (BSelecting Surface Characteristics (Boo, r & z, r & zoo))

– Defining representativenessDefining representativeness– Matching meteorological data with source locationMatching meteorological data with source location

Selecting population for urban runsSelecting population for urban runs Modeling sources in gently down-slopping terrainModeling sources in gently down-slopping terrain Capped and horizontal stacksCapped and horizontal stacks AERMAP:AERMAP:

– Domain boundary Domain boundary – Manual entry of terrainManual entry of terrain

Use of the area source algorithm Use of the area source algorithm

Model ImprovementsModel Improvements Near-Term Improvements:Near-Term Improvements:

– AERSCREENAERSCREEN– Surrogate for on-site cloud cover (Bulk Richardson # approach)Surrogate for on-site cloud cover (Bulk Richardson # approach)

Possible future improvements (e.g.): Possible future improvements (e.g.): – Selecting surface characteristics (AERSURFACE)Selecting surface characteristics (AERSURFACE)– Capped & horizontal stacksCapped & horizontal stacks– Reformulate urbanReformulate urban

– Code optimization Code optimization – Use of gridded met dataUse of gridded met data– Meander for area sources Meander for area sources – PM2.5 Output: 98PM2.5 Output: 98thth percentile concentrations percentile concentrations– Add wind direction dependency for hAdd wind direction dependency for hcc

– Add additional source types:Add additional source types: Line source Line source Buoyant lineBuoyant line FlaresFlares

– Improve BImprove Boo treatment by including soil moisture treatment by including soil moisture

SummarySummary Implementation issues are expectedImplementation issues are expected Implement in a manner that facilitates consistency Implement in a manner that facilitates consistency

in permitting and SIP developmentin permitting and SIP development Implementation process:Implementation process:

– ISC or AERMOD for first yearISC or AERMOD for first year– Provide advice for presently understood issues Provide advice for presently understood issues

(Implementation Guide)(Implementation Guide)– Deal with case specific issues in a timely mannerDeal with case specific issues in a timely manner– Communicate decisions (Clearinghouse Memos) Communicate decisions (Clearinghouse Memos) – Develop formal guidance as experience is gained and Develop formal guidance as experience is gained and

consensus is reachedconsensus is reached– Allow for flexibilityAllow for flexibility– Improve AERMOD as $$$$ allowImprove AERMOD as $$$$ allow