Towards the Use of X-band Dual Polarimetric Radar Rain- Fall Estimates in Urban Hydrology

Cities’ vulnerability to extreme rainfall is increasing due to urbanization, increase of imperviousness, implementation of complex network of infrastructures, and alteration of precipitation patterns as an effect of climate change. More severe and more frequent storms are expected, having a strong impact in urban catchments, which will become more prone to floods. Because of the short duration and rapid variation in intensity especially of summer storms, there is a strong need of both spatial and temporal high resolution rainfall measurements or estimates. Moreover, urban hydrological modelling requires high resolution rainfall data to be able to simulate fast runoff processes and related short response times. This can be provided by X-band radars. In this work, data from IDRA, the dualpolarimetric X-band radar at the Cabauw Experimental Site for Atmospheric Research (CESAR, Cabauw, the Netherlands) are presented, based on a particular rainfall rate retrieval that is independent of the absolute radar calibration and not affected by attenuation as long as the radar signal is not totally extinct. The results show a comparison between three different sources of rainfall data, demonstrating the higher spatial variability of X-band radar data compared to rain gauge and C-band radar data. A first attempt is made to analyse and explain deviations between the rainfall data sources.