A Meteorology-Based Approach to Detecting the Relationship between Changes in SO2 Emission Rates and Precipitation Concentrations of Sulfate

Abstract

In this paper, the authors present an analysis of correlations between SO2 emissions and wet SO2?4 concentrations over eastern North America that includes adjustments for the impact of meteorological variability. The approach uses multiple-regression models and readily available meteorological information to analyze precipitation chemistry data collected from 1979 to 1986 at six Utility Acid Precipitation Study Program site. On an event-to-event basis, from 25% to 50% of the variation in concentrations, depending on site, was found to be related to meteorology. Precipitation amount, temperature, upwind emissions, and upwind mean lower-tropospheric relative humidity (indicator for upwind precipitation) were related to the natural log of SO2?4 concentrations. Inclusion of this information resulted in a decrease in the uncertainty associated with the emission change to concentration relationship at all sites, but the results were inconsistent Year-to-year and season-to-season changes in SO2 emissions were found to be significantly related (p < 0.033) to variations in event and seasonal concentrations at three of the sites, but not at the other three sites. Possible explanations for this discrepancy are discussed in this paper. When all sites were examined simultaneously, strong statistical correlations (p < 0.007) were found between emissions and concentrations, indicating that SO2?4 concentrations decreased in response to seasonal and annual emission changes.