CREATING AERMOD-READY MET FILES: AN UPDATE

1
CREATING AERMOD-READY MET FILES AN UPDATE
Region 4 Modelers Workshop March 10, 2005

• Joe Sims
• Alabama Department of Environmental Management
• [phone] jes_at_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.