EOF-MSE ADAPTIVE METHOD TO ASSESS AN ACID DEPOSITION MONITORING NETWORK OVER ALBERTA, CANADA

Abstract

This study provides an adaptive data analysis method that assesses Alberta's acid deposition monitoring network of 9 stations and the relative importance of each station. The method is based on the assessment of the mean square error (MSE) of sampling expressed in terms of empirical orthogonal functions (EOF). The annual potential acid input (PAI) data of the 9 stations over Alberta, Canada are used in this study. The patterns of the EOFs and PCs (principal components) are analyzed to reflect the PAI's spatial-temporal distribution properties. The definition and minimization of the MSE are the basis for our assessment method. The mean PAI field in the period of 1993–2006 and the PAI fields of individual years demonstrate a strong spatial inhomogeneity of the PAI field over Alberta. The PAI level is high in the Red Deer–Calgary–Kananaskis corridor. Our optimal analysis indicates that the 9-station network is, in general, adequate in monitoring the overall PAI in Alberta. The network results in a small root-mean-square-error/standard-deviation ratio (5.6%), which demonstrates the reasonable effectiveness of the network. In the period of 14 years (1993–2006), there were only three years (1993, 1998, and 2002) during which the PAI values were higher than the monitoring load of 0.17 [keq H+ ha-1yr-1] at three locations: Red Deer, Calgary, and Kananaskis. According to a station's contribution to the reduction of sampling error, the descending order of importance for the 9 stations is as follows: Beaverlodge, Fort Chipewyan, Suffield, Red Deer, Cold Lake, Kananaskis, Calgary, Fort Vermilion, and Fort McMurray.