An integrated procedure for rainfall estimation using C-band dual-polarization weather radars

Weather radar polarimetric techniques have been widely studied due to their potential to improve radar rainfall estimation and to infer on the microphysical characteristics of clouds and precipitation. Nowadays, polarimetric techniques are receiving an increasing attention from meteorological services. In fact, programs aiming at upgrading national weather radar networks with polarimetry are ongoing in both in Europe and in USA. Therefore, there is growing a demand for properly designed products that capitalizes research results in order to obtain improved and reliable meteorological products, such as rainfall estimates, based on polarimetric measurements. This paper presents an integrated methodology which, starting from C-band polarimetric radar measurements, allows to obtain the best rainfall estimation. The procedure takes into account radar meteorology key issues such as: real time calibration check, ground clutter identification, and C-band attenuation correction. The methodology takes advantage of the synergy among radar measurements of reflectivity factor, differential reflectivity, and specific differential phase, as expressed by the self-consistency principle of polarimetric radar measurements in rain. The procedure is evaluated with a case study observed by the ISAC-CNR Polar 55C radar during an intense rainfall event which occurred on 25 September 2006 over the Lazio region (central Italy). A comparison analysis of the method is also performed using rainfall data collected by the hydrographic regional office telemetered network.