Spatial Assessment of Five Years of WSR-88D Data over the Mississippi River Basin and Its Estimation Bias around Rain Gauge Sites

Abstract

Statistical analyses were performed using five years (1996–2000) of Weather Surveillance Radar–1988 Doppler (WSR-88D) weather-radar rainfall estimates that were produced for the Global-Continental Scale International Project over the entire Mississippi River basin. The project radar rainfall estimates were adjusted using a Z-R relation optimized to improve performance at the time scale of individual storms. The accuracy of radar-rainfall estimates were analyzed during the warm season considering a number of factors, including number of overlapping radars, distance from gauge to nearest radar, gauge elevation, and the geographic location of the radar. Results were used to identify optimal radar-rainfall estimation areas (ORREAs) within the Mississippi River basin with high correlation between storm-total radar and rain gauge rainfall. Additionally, estimation of the bias between storm-total radar-rainfall and rain gauge rainfall accumulations in areas without gauges was assessed to identify the appropriateness of applying bias adjustments derived from gauge data at points away from those rain gauges.