Climatological Analysis of the Hubbard Brook (New Hampshire) Precipitation Chemistry Data. Final Report

摘要

Precipitation chemistry data from Hubbard Brook, NH are of two types: event measurements, June 1975 to July 1978, inclusive; and weekly measurements from 1963 to May 1980, inclusive. In both cases, concentrations are available for a range of chemical constituents of the precipitation samples. Five-day back trajectories have been computed for the storms. Together with a crossing-trajectory analysis, the results show the influence of source regions on the chemical climatology of Hubbard Brook. With respect to the weekly measurements, the statistical properties of the data set have been investigated, and 850-mb precipitation chemistry wind roses for Portland, Maine have been constructed. The latter show that Na concentrations are high with ENE-SE winds and that the Ca/Na ratio is a good indicator of off-ocean vs off-land flows. Other results of the wind-rose analysis include: H exp + deposition and SO sub 4 deposition are high with S to WSW winds; NO sub 3 and H sub 4 concentrations are high with W-NW-N winds; and SO sub 4 concentrations are high with N-NE-E winds. Time series analyses of the 16-year data set have been undertaken. The results suggest: downward trends in concentrations of Na, Cl, Ca, Mg, K and Al and the ratio SO sub 4 /NO sub 3 , and upward trends in NO sub 3 deposition and the ratio NO sub 3 /Na; in the case of pH, SO sub 4 , NO sub 3 and NH sub 4 , the time series seem to have changed slope about 1971; for the subset of cases with 850-mb winds from 300 to 069 deg., there is no trend in pH but a significant decline in SO sub 4 and NO sub 3 in winter; based on regional emission inventories for SO sub 2 and NO/sub x/ for the years 1965, 1970, 1975 and 1978, higher normalized wet depositions of SO sub 4 and NO sub 3 are associated with years having higher regional emissions of SO sub 2 and NO/sub x/, respectively. 15 references, 108 figures, 17 tables. (ERA citation 09:025062)