Evaluation of KUPR algorithm in matchup cases of GPM and TRMM

GPM Core Observatory satellite has been in operation since February, 2014. Before the GPM operation started, TRMM had observed the rain rate in tropical regions. GPM´s KuPR is a successor of TRMM/PR, and both have the same design [1]. However, differences have been confirmed in their estimates for the same rainfall. Therefore, we focus on the retrieval method of rain rate, and compare the rain rate estimates by KuPR and PR. As a result of comparison, path-integrated attenuation (PIA), surface reference technique (SRT) and non-uniform beam filling (NUBF) are regarded as the factors of differences of the rain rate. Particularly, overestimation of PIA in KuPR is one of the most important factors of the differences of rain rate. On the other hand, rain rate is overestimated in KuPR when SRT is ignored. Therefore, the number of cases is needed to be increased, and it is necessary to improve the parameters of SRT and NUBF.