The early detection of sulphur emissions reductions using Wet Deposition Measurements

This paper is the outgrowth of a workshop on the Detection of Trends in Wet Deposition Data, attended by atmospheric modellers, atmospheric chemists and statisticians in Toronto, November 1983. Methods for detecting changes or trends in network data which are described and evaluated include statistical and meteorological analyses of 'before' and 'after' time series at single stations, the analysis of changes in frequency distributions, and the analysis of entire network data sets. Relative advantages of using precipitation concentration vs deposition data sets are examined, and the added information on trends available from air concentration measurements (SO₂ and particle-SO₄^2-) is shown. The paper concludes with recommendations for data requirements and preferred approaches to trend or change detection using available statistical and modelling techniques.