Microphysical features of solid/melting particles by Ground-based direct observations for the GPM/DPR algorithm development

We carried out the intensive observation for the GPM/DPR ground validation at Mt. Zao during 2014–2015 winter season, targeting the melting layer. For the better understanding of microphysics in the melting layer, we developed Ground-based Particle Image and Mass Measurement System (G-PIMMS). It can capture particle images by CCD cameras and measure particle weight by the electronic balance. G-PIMMSs were installed at two different altitudes on the hillside of Mt. Zao between two confronting Ka radar sites. We often experienced sleet or wet snow on the ground in early/late winter season, and succeeded in observation of the melting layer. Rain and snow, including sleet, were discriminated at 1.5–2.1°C in wet-bulb temperature. It was also found the density of precipitation changing with temperature between 0°C and 2°C.