Yuki Kaneko

The orbital operations status of the dual-frequency precipitation radar on the global precipitation measurement core spacecraft

The Dual-frequency Precipitation Radar (DPR) installed on the Global Precipitation Measurement (GPM) core satellite was developed by JAXA and NICT. This paper describes mission objectives, technical performance, resource allocation, design, proto-flight test (PFT) of the DPR instrument, satellite system test including launch operations and orbital check out results of the DPR. The DPR system PFT has completed in February 2012. DPR has handed over to NASA and integration of the DPR to the GPM core spacecraft have completed in May 2012. GPM core spacecraft satellite system test has completed at NASA Goddard Space Flight Center. GPM core observatory was shipped to JAXA Tanegashima Space Center, JAPAN and Launch Site Operations has completed. GPM core observatory was successfully launched by H-IIA launch vehicle on Feb 28, 2014. DPR orbital check out had started in March 2014 and it was completed in May 2014. The orbital check out results of DPR is reported in this paper.

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.

Snow measurement using a dual Ka-band radar system for GPM/DPR algorithm development

Both equivalent radar reflectivity factor (Ze) and specific attenuation (k) in several snow events are measured using a dual Ka-band radar system. Different k-Ze relations are obtained depending on surface air temperature. When surface air temperature is just above 0 °C, k-Ze relations scatter and larger k values than those of rain appear. On the other hand, when surface air temperature is below 0 °C, both k and Ze are small and a slight positive trend appears in the k-Ze relations. The difference of k-Ze relations can be attributed to the difference of the backscattering and attenuation characteristics between wet and dry snow. To confirm wet/dry snow existences, 2D-video-disdrometer data are analyzed. Velocity-size distributions of wet snow events are different from those of dry snow events. Graupels also show different velocity-size distributions from wet and dry snow particles with different k-Ze relations.