Influences of atmospheric circulation on the variability of wet sulfate deposition

Uri Dayan*, Dennis Lamb

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

Precipitation chemistry data from the National Atmospheric Deposition Program were related to weather data from the Climate Diagnostics Center in order to reveal the influence of large-scale circulation patterns on the wet deposition of sulfate downwind of the Ohio River Valley, where SO2 emissions were curtailed sharply in the mid-1990s. The chemistry data from five precipitation-sampling sites were combined to provide a regional average for each summer season over the 21-year period from 1984 to 2004. The long-term trend of sulfate concentration is associated to a statistically significant extent by composited flow patterns associated with the East Pacific-North Pacific index. The regional weather pattern for the sulfate-rich years is associated with an intensification of the Bermuda High over the southeastern United States at the surface in tandem with a weakening of the 500-hPa. geopotential height (GPH) climatological trough located over the northeastern United States. The highest-sulfate concentration days for the Atmospheric Integrated Research Monitoring Network (AIRMoN) Pennsylvania site occurred during a similar synoptic pattern when intense convection over the eastern United States was favoured thermodynamically. This study suggests that temporal changes in the large-scale circulation pattern over North America need to be considered, in addition to changes in precursor emissions, as an explanation for the decreases in sulfate concentrations observed in summertime rains across the eastern United States.

Original languageEnglish
Pages (from-to)1315-1324
Number of pages10
JournalInternational Journal of Climatology
Volume28
Issue number10
DOIs
StatePublished - Aug 2008

Keywords

  • AIRMoN
  • Circulation patterns
  • NADP
  • NTN
  • Sulfate deposition
  • Wet deposition

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