The Characteristics of Raindrop Size Distribution and Drop Shape Relation in Typhoon Systems from 2D-Video Disdrometer and NCU C-Band Polarimetric Radar

The Drop Size Distribution (DSD) and Drop Shape Relation (DSR) characteristics of different precipitation systems have been investigated in numerous regions. However, the characteristics of DSDs and DSRs in typhoon systems are still poorly documented despite typhoons cause lots of damages all over the world. In this present research, authors focus on the DSDs and DSRs observed in typhoon systems in northern part of Taiwan in Western Pacific and compare with the DSDs retrieved from the polarimetric measurements. There were 13 typhoon cases DSD data were collected and analyzed. The time series of the vertical profile of reflectivity and the surface DSDs of two rainband cases were fully illustrated to understand the evolution of the DSDs and its relation with the vertical development of the reflectivity. The drop shape relation (DSR) in typhoon system was also derived and compared with the DSR in non-typhoon system. The result indicated that the raindrops in typhoon system were slightly more spherical than the non-typhoon condition. The DSDs retrieved from one typhoon case observed by NCU-C-band dual-polarization radar, together with another two disdrometer derived DSDs were compared with the DSDs of the continental and maritime convection systems. The results indicated that in the scatter diagram of the normalized intercepts and mass weighted diameters, the cluster from typhoon systems is uniquely located in between of the other two clusters from the continental and maritime systems.