Rainfall spatial variability observed by X-band weather radar and its implication for the accuracy of rainfall estimates

Abstract: The main objective of this paper is to estimate the error in the rainfall derived from a polarimetric X-band radar, by comparison with the corresponding estimate of a rain gauge network. However the present analysis also considers the errors inherent to rain gauge, in particular instrumental and representativeness errors. A special emphasis is addressed to the spatial variability of the rainfall in order to appreciate the representativeness error of the rain gauge with respect to the 1km square average, typical of the radar derived estimate. For this purpose the spatial correlation function of the rainfall is analyzed. The data set consists of 1-year radar data collected by the X-band polarimetric radar HYDRIX®, located in Beauce region (80km south of Paris). All data were processed in real time using the ZPHI® algorithm. A dense 25 rain gauge network provided ground comparison data. The various sources of uncertainties (instrumental and representativeness) are then analyzed and quantified for each sensor. [Copyright &y& Elsevier]