Combined analysis of C-band polarimetric radar and disdrometer data of convective and stratiform precipitation

The aim of the present Thesis is to observe the characteristics of the precipitation and to check the quality of the radar data under different meteorological conditions. This aim is achieved through a combined analysis of the data collected by two instruments that have different operating principles: a C-band polarimetric radar and a PARSIVEL2 disdrometer. Radar variables are compared with the characteristics and the microphysics evolution of the precipitation retrieved by the disdrometer. The disdrometer is located in the city center of Bologna, at about 28 km far from the radar site. The combined analysis of the two instruments is done for a dataset that includes 11 months of the years 2019 and 2020. The dataset contains convective and stratiform precipitation events. The lower radar elevations are affected by anthropogenic interferences that slightly reduce the dataset extension. The analyses show a good correlation between the reflectivity factors retrieved by the radar and by the disdrometer through the Drop Size Distribution (DSD). The correlation coefficient between the two estimations is 0.84. A verification of the operational algorithm of the hydrometeor classification is obtained through the radar data. Moreover, the convective and stratiform discrimination developed through the disdrometer data is consistent with the polarimetric variables of the radar. For example, the distribution of the differential reflectivity peaks for higher values in a regime of convective precipitation in comparison to the stratiform regime. The convective distribution of the differential reflectivity has a median of 1.5 dB, while the stratiform one has a median of 0.9 dB. Lastly, the case study of a thunderstorm occurred in Bologna on May 28th 2019 is described. This case study shows precipitation structures of different intensities and different types of hydrometeors, allowing a verification of the previous results and a more-detailed analysis of the DSD characteristics.