It is important to know the distribution of the ice-phased perticles, because the perticles like snow and graupel are closely related to the precipitation fomation process. In this study, to reserch the destribution of them, the X-band polarimeric radar data which can observe them for wide range and high frequency were selected. The characteristics of the precipitation systems occured around the East China sea are the heavy rain dispite of the humid at the lower layer and shallow convective systems. The precipitation formation pricess of the precipitation systems are not completly explained yet. Then, intensive field observation of baiu precipitaion were carried out in the Okinawa region from 23 May to 27 Jun in 2011 and 7 May to 17 Jun 2012.

To clarify the distribution of the ice-phased particles around the East China sea, the precipitation systems were divided into 3 groups. (A) the region of stratiform precipitation, (B) the region of isorated convective cell, (C)the region of convective cell embbedded in stratiform precipitation. In this study, to reserch the precipitation perticles, X-band polarimetric radar data were used for hydrmeteor classification. In this study, 1382 baiu precipitation systems are classified. Then, 465 systems are classified to A guroup, 23 systems are classified to B group, 60 systems are classified to C group, and 834 systems are not classified.

Few dry graupel and wet graupel were identified through all precipitation groups, and ice cristal and dry snow were dominance above the melting layer. The data from HYVIS which can film above melting layer were used for verification of hydrometeor classification, and few supercooled water droplets were observed. So, the characteristics of baiu precipitation systems around Okinawa region are almost stratiform and few dry graupel and wet graupel particles are distributed above melting layer. It is suggested that the heavy rain on the Okinawa region is not relate to ice-phased process, but relate to coalescence process.