The U.S. EPA released a new version of the AERSURFACE tool in early 2020. AERSURFACE is used to develop direction-specific estimate of surface characteristics (albedo, Bowen ratio, and surface roughness length) for use as input in AERMET processor to produce meteorological data sets that can be used in regulatory dispersion modeling analyses using AERMOD. The latest AERSURFACE tool was revised from the previous version to allow input of more recent land use data sets (e.g., 2001, 2006, 2011, and 2016 vs. only 1992 previously) and additional data resources (e.g., percent impervious and percent tree canopy data). Changes in land use classification schemes between the 1992 and later data sets required the U.S. EPA to re-evaluate the assignment of surface characteristics to different land use types. In some cases this re-evaluation has been observed to result in considerable differences in surface characteristics output for a location using the latest version of AERSURFACE compared with the previous version.
This paper presents a case study applying the current and previous AERSURFACE program to a meteorological data location. The analysis evaluates actual changes in land use in the time period between land use data sets and changes to assigned surface characteristics that are a function of the AERSURFACE version used. AERMOD is run for a series of hypothetical sources to determine the impacts on concentration outputs resulting from any changes observed in land use characterization. Changing from 1992 to 2016 NLCD data had a larger impact on AERMOD outputs compared with varying sector definitions or snow/no snow inputs.
