AERMOD Meteorological Data Correction

July 14, 2006

An error was discovered in the recently created meteorological data for AERMOD. A single hour in the Dubuque data (hour 10 on 7/9/2002) contained an erroneously low wind speed of 0.5 m/s (the correct value is 4.6 m/s). Sensitivity tests indicated that the lower wind speed could cause the model to predict significantly higher results during shorter averaging periods (as much as a factor of two when comparing maximum one hour concentrations). Therefore, it was necessary to correct the data.

Future modeling conducted using the Dubuque data should utilize the corrected data. All copies of the previous data should be deleted. Only modeling analyses conducted in Allamakee, Clayton, Dubuque and Jackson Counties are affected by this correction.

The corrected data can be found on the Air Quality Bureau’s website here:

www.iowacleanair.com/prof/tech/AERMODMetData.html

Questions regarding the meteorological data should be directed to Brad Ashton of the Air Quality Bureau. He can be reached by telephone at (515) 242-6532 or by email at Brad.Ashton@dnr.iowa.gov.