Have the Number Of Coastal or Easterly Precipitation Events in Southeastern NY Increased
and How Does This Affect the Overall Trend in Precipitation Chemistry?

Victoria R. Kelly, Kathleen C. Weathers and Gary M. Lovett
Institute of Ecosystem Studies Box AB, Millbrook, NY 12545

An increase in the number of storms in the northeastern US that come from the east could have a strong influence on precipitation chemistry in that region. At our research site in southeastern New York, most storms come from the west, traveling through areas heavily populated by coal burning power plants and carrying pollutants that cause acid rain. On average, easterly and coastal storms have a higher pH and lower concentrations of sulfate and nitrate than storms that come from the west. The trend in precipitation concentrations of hydrogen ion, sulfate and nitrate since 1984 at the Institute of Ecosystem Studies is a decreasing one that corresponds to a decreasing trend in emissions of sulfur dioxide and oxides of nitrogen. If the number of easterly storms increases, the trend in average precipitation sulfur and nitrogen could take more of a downward trend than expected based on changes in sulfur and nitrogen emissions alone. In this paper, we examine the change in precipitation chemistry together with an analysis of storm direction during the period 1984-2006 to determine whether the changes in precipitation pH, sulfate and nitrate could, in part, be because the path of storms has changed and not only as a result of reductions in sulfur and nitrogen emissions.