Effect of Atmospheric Stability on Modeling Air Quality in and Around a Major Airport

Abstract

The impact of aircraft emissions on air quality is a major public health problem for communities near airports. It's difficult to quantify aircraft emissions and accurately model the air quality impacts of these in dispersion models. Airports located near a coast face additional challenges since meteorological conditions are not spatially homogeneous in and around the airport. The changes proposed in this study incorporates the features that define overall dispersion of aircraft emissions near a coastal region. To evaluate comparisons of these features with the AERMOD dispersion model, the SO2 concentration measurements at a single site (CS) from the Los Angeles Air Quality Source Apportionment Study (LAX AQSAS) conducted during February 2012 have been utilized. As part of the LAX AQSAS, high frequency observations of NOx, SO2 and several other pollutants were collected at four core (AQ, CN, CS, and CE) locations during the study period at the Los Angeles airport. The qualitative performance of AERMOD incorporating atmospheric stability and roughness length changes is improved in terms of explaining the hourly diurnal pattern of observed concentration distribution at site CS. In addition, the quantitative analysis based on the fraction of model predictions within a factor of two of the observations (FAC2) improved from 0 to 27% and the ratio of medians of the observed to the predicted concentrations dropped from 4.2 to 2.8 at site CS.