Analysis of radar and raingauge measurements for a critical meteorological event in Tuscany

In this paper, some considerations are given to the employment of C-band polarimetric weather radars for rainfall estimates. The most common error sources are discussed, such as ground clutter and propagation attenuation effects, together with decorrelation in the sampling at the ground between radar and raingauge measurements, which can be quite significant in radar systems located in hilly regions, as is the case of the Arno basin in Tuscany. Since the main objective from a hydrological point of view is the estimate of rainfall at ground, integrations and comparisons are needed between radar and raingauge data, which are characterized by different time and space sampling. The paper is then focussed mainly on this problem and a technique is presented in order to improve radar based rainfall estimates through the integration with raingauge data, in order to enhance the correlation between the two types of measurements. Such a method is finally applied to a serious meteorological event which affected the Arno basin on October 1992.