AERMOD Modeling Syste

Status and Updates

Roger W. Brode

U.S. EPA/OAQPS

Air Quality Modeling Group

9th Conference on Air Quality Modeling

October 9, 2008

Research Triangle Park, NC
Outline

• Recap of AERMOD status• Recent AERMOD developments

– AERMOD dispersion model– AERMAP terrain preprocessor– AERMET meteorological preprocessor

• Other AERMOD-related activities
• Promulgated as EPA-preferred near-field model 

Register notice dated November 9, 2005, with efdate of December 9, 2005, as version dated 043

• One-year grandfather period expired December 

• Significant updates to all AERMOD components 

January 2007 (dated 06341), with limited update 

AERMOD (dated 07026)

– AERMOD model changes included enhancements to improv

urban-scale applications

• Additional options to vary emissions by month, hour-of-day and 

(MHRDOW, MHRDOW7)

• Multiple urban areas in single model run• Improved memory management

– Updates to PM-2.5 processing in AERMOD– Beta-test options for capped/horizontal releases and for PVM

credit option

AERMOD Status
• AERMET v06341 updates included signific

changes to processing of NWS Integrated Hourly Data (ISHD) surface data (TD-3505

– Selection of which record to process for hours 

multiple records

– Processing of cloud cover codes– Identify “variable” winds as missing WD and n

missing WS rather than calm

• Several additional bug fixes in AERMET• Single AERMET executable

AERMOD Status - AERM
• Significant changes in AERMAP v06341 re

horizontal datum (NAD) conversion proces

– Previous version did not account for shift due t

Lat/Lon conversion

– Error typically about 200m in Northing coordin– Incorporated NAD conversion for DOMAIN ext– Clarified and simplified treatment of DEM file g

• Corrected bug with method to optimize hil

scale calculation by skipping adjacent DEM 

• Enhanced debug output options, fixed sev

bugs, and incorporated additional optimiza

AERMOD Status - AERM
• Updates to all three AERMOD component

completed (dated 08280):

– To be released on SCRAM ASAP– Miscellaneous bug fixes and enhancements fo

AERMOD components (more details on follow

– Improvements in code portability across comp

platforms (Windows/Linux) for all components

– Update to Intel Fortran Compiler for distributed 

executables (about 40% runtime improvement compared to Compaq Visual Fortran)

– User’s Guides being updated to incorporate Ad

other corrections

Recent AERMOD Developm
• Modified optional urban roughness length to treat values ot

meter as non-DFAULT (per discussion in Section 5.3 of AE

Implementation Guide

)

• Added options to vary emissions by hour-of-day and day-of

(HRDOW and HRDOW7)

• Enhanced HOUREMIS option to allow specifying hourly-va

heights and initial dispersion coefficients for VOLUME and sources

• Corrected significant bug with use of OLMGROUP keyword 

option; more details in Addendum to Model Change Bulletin 

• Corrected problems with processing of surface file header f

meteorology, for interface with AERSCREEN

• Improved efficiency of memory allocation (especially for AR• Use of DOUBLE PRECISION for nearly all non-integer vari

– addresses some long-standing and recent issues with precision– also improves consistency of results across different compilers, comp

computing platforms

Recent AERMOD Chang
• Fixed problems with processing Alaska DEM files (1-d

and 7.5-min data; non-uniform longitude spacing of no

• Support for National Elevation Dataset (NED), availab

USGS Seamless Data Server in GeoTIFF format

• Allow “mixed” DEM files (1-deg, 7.5-min, and 15-min f

be used to fill gaps in 7.5-min coverage, such as over 

however, no support for mixed DEM & NED data

• Domain keywords (DOMAINXY/DOMAINLL) are now 

use all available data if omitted

• Support for INCLUDED keyword on RE and SO pathw• Modified to use standard convention of negative for W

– Simplifies code structure and inputs– Consistency with other tools (e.g., AERSURFACE)– Improves applicability beyond the U. S.

• Allocatable array storage at runtime

Recent AERMAP Chang
• Corrected cosmetic bug with user-specified station ele

incorrectly reported as 100m in Stage 3 report file

s

• Corrected problems with averaging of sub-hourly input

specific data

• Make broader use of station elevations from data files 

SAMSON) and/or user-specified elevations for SURFA

• Corrected problems with time zone adjustments for ca

surface and onsite stations in different zones

• Added optional user-specified upper air sounding wind

currently hardwired to 11-13Z

• Incorporated changes to handle ISHD files with “proble

addressed on interim basis by FIXISHD utility

Recent AERMET Chang
• Updating Air Pollution Training Institute (APTI) course 

“Dispersion of Air Pollution: Theory and Model Applicreflect AERMOD model

• Support for in-house applications of AERMOD, includ

– Application for “Detroit MP Study” to model local-scale impact

HAPs, combined with CMAQ results using “hybrid” approach

– Model-to-monitor comparisons for Benzene emissions from T

refineries for RTR

– Support to Alabama DEM for Birmingham Area Particulate St

(discussed this morning)

– Exposure assessment for Atlanta area to support current NO

2 

review (more on this tomorrow morning)

– Common themes are meteorological data representativeness 

processing, source characterization and emission uncertaintieperformance on a paired-in-space and/or time basis (more on morning)

Other AERMOD-related Act
• Developing infrastructure to support more efficien

to AERMOD modeling system, with full assessmeimpact of model changes

– Developing more effective procedures to challenge mod

prior to release, including more comprehensive test bedtesting across multiple compilers and computing platfor

– Automating process of assessing impact of model chan

routine application of consequence analysis databases evaluation field study databases

– Developing procedures for notifying community of signif

or other issues, with information on potential impacts, wany, and status of fixes

– Provide clearer procedures and mechanism for reportin

with the AERMOD modeling system to EPA and trackin

response/resolution

Other AERMOD-related Act
• Assessing application issues related to AERMOD 

system and coordinating work of AIWG and AERMaddress these issues

– Modeling impacts from haul roads

• Coordination with CRA and other stake-holders in assessi

updates to AP-42 emission factors

• Assessing source characterization issues to develop “best 

recommendations for modeling haul roads

• Addressing consistency issues across Regions and States

– Meteorological data representativeness and sensitivity to 

characteristics

• Conducted AERMOD sensitivity analysis study, presented 

Annual Conference in June 2008; plans to expand confere

more complete EPA report

• Activities of AIWG to develop better understanding of issue 

improving guidance; plans of AERMIC to enhance AERMto mitigate this issue (discussed later in this session)

Other AERMOD-related Act
Questions?