The Application of RadarGauge Comparisons to Operational Precipitation Profile Corrections

Abstract The analyses of data recorded during the past eight years with two Swiss radars, a network of rain gauges, and river flow measurements have helped to quantify the vertical profile of reflectivity and the influences of topography, meteorology, and radar parameters on the precision of radar precipitation estimation. The influence of the topography around the radar, the width of the radar beam, and the vertical echo structure produces a complex error distribution in space and time, with errors dependent upon storm type, distance from the radar, and the radar horizon. In spite of excellent agreement between amounts estimated by the 5-cm radar at close ranges and gauges located below the radar volume, underestimation of rainfall increases with range from the radar. The authors' experience dramatically shows how significantly errors are reduced when precipitation can be estimated close to the ground, a task made easier by choosing a radar site with a good view and by rigorously eliminating echoes conta...