Extending cluster analysis—synoptic meteorology links to characterise chemical climates at six northwest European monitoring stations

Clustering isobaric trajectories, a technique used in an earlier study to help relate synoptic weather patterns to precipitation chemistry observed at Eskdalemuir, has been extended to five other northwest European-monitoring stations. The combined power of trajectory clustering and precipitation amount explains a greater degree of day to day variability in precipitation chemistry at three U.K. stations relative to three Norwegian stations. This explanation rises to 55% for summer season nitrate concentrations at Goonhilly in southwest England. Topographic effects and the combination of heavy precipitation, when transport is from a polluted sector, confounds this approach when applied to Norwegian stations. Prediction of ion deposition at Eskdalemuir, basest simply on trajectory and precipitation amount information, has been extended to the years 1985 and 1987, with encouraging accuracy. The success of this approach when applied to U.K. conditions suggests that a basis for estimating future levels of acidic deposition in the U.K. may lie in predictions of atmospheric circulation patterns resulting from natural or anthropogenic climate change (assuming emissions remain constant in their magnitude and distribution).