Journal of Official Statistics, Vol.5, No.4, 1989. pp. 433–455
Assessment of Temporal and Spatial Variability in Wet Sulfate and Nitrate Deposition
Mayer Alvo and Eva Voldner
Abstract:Precipitation chemistry measurements are collected in North America in part to monitor changes and to detect temporal trends in deposition. An analysis using seasonal wet sulfate and nitrate data over the period 1980–1984 is proposed. A principle component analysis indicates that there are no significant spatial shifts in the data. Seasonal deposition estimates for each of five regions are then determined by kriging. Temporal trends are assessed using first a run test. Subsequently, a pairwise seasonal comparison taking into account estimates of deposition uncertainties is used. The study reveals that there are significant temporal trends in sulfate and nitrate deposition in a region which includes South Eastern Ontario. The causes of the trends however, cannot be determined without the aid of a comprehensive model which takes into consideration the atmospheric processes.
Keywords:Trends; wet sulfate and nitrate; principle component angle; kriging; run test.
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