Precipitation observation using a dual Ka-band radar system

A dual Ka-band radar system is developed by the Japan Aerospace Exploration Agency (JAXA) for the GPM DPR algorithm development. The dual Ka-radar system which consists of two identical Ka-band radars can measure both the specific attenuation and the equivalent radar reflectivity at Ka-band. Those parameters are important particularly for snow measurement. Using the dual Ka-radar system along with other instruments, such as a polarimetric precipitation radar, a windprofiler radar, ground-based rain measurement systems, the uncertainties of the parameters in the DPR algorithm can be reduced. The verification of improvement of rain retrieval with the DPR algorithm is also included as an objective. Observations using the dual Ka-radar system were performed in Okinawa Island, in Tsukuba, over the slope of Mt. Fuji, and in Nagaoka, Japan. In Okinawa Island, the performance of the measurement has been confirmed by rain observation. In Tsukuba, one radar was directed in vertical and the other was in slant direction. By this configuration, total attenuation in the melting layer was estimated. The objective of the Mt. Fuji experiment was to observe the melting layer. In Nagaoka, a lot of wet snow fell, and much data on the snow have been obtained. The main results are measured k-Ze relationships. For the rain, reasonable k-Ze relationship has been obtained. The feasibility of total attenuation in melting layer has been studied. Different k-Ze relationships have been obtained in snow observations.