INVESTIGATION OF DISCONTINUITY IN PRECIPITATION MEASUREMENTS ACROSS CANADA AND U.S. BORDER

Abstract

This dissertation focuses on the discontinuity in precipitation measurements across Canada and U.S. border. Incorrect precipitation data may cause inhomogeneous precipitation distribution, which can result in incorrect spatial interpretation. This study quantifies the bias-corrections for the systematic errors (i.e. wind-induced gauge undercatch, wetting loss, and trace precipitation) in the historically national standard manual gauges (Nipher gauge and Type B rain gauge for Canada and NWS 8-inch gauge for U.S.). This study uses the statistical method to compare the measured and corrected precipitation measurements for each pair of the station across the border. It also applies regression analysis to examine the correlation between each station pair and the changes in precipitation relationship due to the bias-corrections. Moreover, a double mass curve (DMC) analysis was conducted to present the changes in cumulative precipitation over time. Overall, the conclusion of this study is that the bias-correction is greater for NWS 8-inch gauge than for the Canadian Nipher gauge, and also, the bias-correction is higher in the cold season than in the warm season. The DMC also quantifies significant discontinuity in the measurements across Canada and U.S. border. The contributions of this study include: improve the understanding of precipitation change due to the systematic errors (bias-corrections); document the changes in precipitation amounts and distribution due to bias-corrections; and quantify significant discontinuity in the precipitation measurements across Canada and the U.S. border. This study will benefit regional climate and hydrology research.