Combining single polarization X-band radar and ground devices for hydrological applications

Recently, the Department of Civil, Environmental, Aerospace Engineering, and Materials (DICAM) of the University of Palermo (Italy) has installed several devices for the monitoring of precipitation for the urban area of Palermo. These devices include a single polarization X-band weather radar, a rain gauge network spread over the urban area, and a laboratory site where advanced precipitation devices (an optical disdrometer, a weight rain gauge, and a weather station) are available. Given the ensemble of measurements retrieved by sensors, a set of models for the combination of data has been developed in order to exploit their joint usage. The disdrometer information have been exploited for the calibration of both the radar equation and the Z-R relation. The availability of rain gauges data is considered for the implementation of a correction procedure that is aimed to the improvement of congruence between ground rain references measurements, and the radar estimates. The application framework has been evaluated with reference to their specific potential suitability for both hydrological and meteorological applications. The analyses have been carried out with reference to long measurement series for calibration models, and considering some specific events for the validation of results. A one year-long measurement record retrieved from the disdrometer has been analyzed for the characterization of the temporal variability of the Z-R relation and the determination of the best setting strategy. The study confirms the opportunity of coupling the radar system with auxiliary instruments that significantly contribute to the quality of final estimates. The contribution of the sensor blending is particular worthy for hydrological rainfall, while for meteorological applications a trade-off between calibration/correction procedures and the readiness of data has to be considered.