AERMOD Meteorological Data Update
On January 18, 2013 the Environmental Protection Agency (EPA) released a new version (13016) of the AERSURFACE preprocessor to AERMOD’s meteorological pre-processor AERMET. The new version incorporates several important changes that can significantly affect the average surface roughness values that are input into AERMET. A summary of the changes to AERSURFACE can be found in the model change bulletin available on EPA’s Support Center for Regulatory Air Quality Models (SCRAM) website
. In response to these updates the Department has reprocessed all of the 2005-2009 meteorological datasets using the new version of AERSURFACE.
Previous analyses have indicated that AERMOD is sensitive to the surface roughness values used in AERMET. Sensitivity tests were conducted using the new meteorological data. The results of these tests indicate that there should be an average change in maximum modeled concentration of less than 1%. Of the various combinations of source types and averaging periods analyzed, 98.4% resulted in maximum concentrations that were within 5% of the maximum concentrations predicted using the previous meteorological dataset.
The new meteorological data can be differentiated from the previous versions by the letter “D” appended to the end of the file names. Applicants should begin using the new meteorological data immediately. The data can be found on the Department’s meteorological data webpage
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