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CREATING AERMOD-READY MET FILES: AN UPDATE

CREATING AERMOD-READY MET FILES: AN UPDATE. Region 4 Modelers Workshop March 10, 2005. Joe Sims Alabama Department of Environmental Management (334) 279-3079 – jes@adem.state.al.us. Alabama AERMET Project.

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CREATING AERMOD-READY MET FILES: AN UPDATE

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  1. CREATING AERMOD-READY MET FILES: AN UPDATE Region 4 Modelers Workshop March 10, 2005 Joe Sims Alabama Department of Environmental Management (334) 279-3079 – jes@adem.state.al.us

  2. Alabama AERMET Project Purpose – Establish a set of fully reviewed and approved meteorological data and land characteristic files for the NWS weather stations used in Alabama PSD Air Quality Analysis modeling.

  3. Rationale for Project • PSD applicants/consultants will have starting point for their air quality analyses. • Applicable surface (*.SFC) and upper air (*.PFL) files available to consultant. • Subjectivity removed from this part of Air Quality Analysis. • Removes potential for gaming. • Consultant will be responsible for demonstrating that the surface characteristics are representative of the facility under review.

  4. Approach • Divide the State into climatologically & topographically similar domains. • Identify NWS surface station most representative of each domain. • Identify representative NWS upper air station for each domain. • Determine land characteristics for each surface station. • Run AERMET Stage 1 through Stage 3 for each domain and create *.SFC and *.PFL files for input to AERMOD. • Submit results and documentation to Region 4 for review, comment and approval.

  5. Determining Land Characteristics • Divide 3 kilometer circle around weather station into 12 segments. • Divide year into seasons. • Use as many sources as possible to best estimate surface characteristics in each sector, for each season. • Suggested sources: • www.landcover.usgs.gov (national landcover maps based on Landsat thematic mapper data – 30m resolution) • www.edcftp.cr.usgs.gov/pub/data/LULC/ (250m resolution landcover/land use data) • USGS Quadrangle maps • www.topozone.com (online Quad maps) • www.globexplorer.com (satellite and aerial photos) • www.terraserver-usa.com (satellite and aerial photos) • www.landvoyage.com (satellite and aerial photos) • personal experience, • Use weighted average of characteristics in each sector, rounded to 2 decimal places (arbitrary – no guidance). • Run AERSURFACE for each weather station for a sanity check.

  6. Birmingham 3km SectorsUSGS Land Use

  7. USGS Land Use – AERMET Conversion

  8. Birmingham Land Use Based on 250m LULC(Processed by CALMET)

  9. Internal Methodology & QA • The nine stations divided among 4 people to estimate characteristics for 2 or 3 stations each. (DONE) • Estimates based primarily on high-resolution USGS Land Use charts. (DONE) • Estimates adjusted as necessary based on USGS Quad charts and aerial photos. (DONE) • Estimates adjusted as necessary based on USGS 250m LULC charts. (DONE for BHM only) • All station characteristics to be reviewed as a committee and final numbers agreed upon. (DONE for BHM only) • Run AERSURFACE as another check (annual only). (DONE)

  10. Birmingham AERMET Surface Characteristics - Compared

  11. Lessons Learned • Difficult to distinguish between coniferous and deciduous forest using the tools we have. • USGS land use maps big help but sometimes appear unrealistic. • When in doubt, tended to use a ratio based on our collective experience with the area. • Difficult to distinguish between cultivated land and grassland using the tools we have. • Is grassland like prairie, like pasture, or like lawn grass? Or does it matter? • Subjectivity involved in comparing land use categories used by USGS and by AERMET.

  12. Issues • What is sufficient justification for using NWS data as representative of the weather and surface characteristics at the facility under review? • Need better guidance (in GAQM?) from EPA. • Will EPA expect a sector-by-sector comparison? • Will EPA expect a parameter-by-parameter comparison? • How will EPA minimize the subjectivity involved?

  13. Issues (Continued) • Will representativeness issue force more site-specific weather towers? • Can ASOS weather station data be used to help relieve some of these problems? • An ASOS station closer to the facility under review might be more representative than a manned station.

  14. Issues (continued) • The consensus seems to be to examine land use within a 3 kilometer circle around the site. If this is to be the standard, EPA should so state. • We arbitrarily chose to round characteristics to 2 decimal places. Should we use 3? One? How sensitive is AERMOD to these factors? EPA guidance would be helpful here. • We arbitrarily chose to divide the 3 kilometer circle into 12 sectors. More EPA guidance would be helpful here.

  15. Conclusion • Modeling protocols will become even more important in the AERMOD era. • We foresee much closer coordination with EPA Regional Offices required in the AERMOD era to resolve modeling issues. • We foresee much longer review and approval times for all Air Permit applications.

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