Improvement of the GSMaP Precipitation Retrieval Algorithm for Microwave Sounders Over Coast

We have improved a rainfall retrieval algorithm over coast for the Advanced Microwave Sounding Unit (AMSU) in order to upgrade to the Global Satellite Mapping of Precipitation (GSMaP) product version 8. As for the algorithm of product version 7, the zonal-mean monthly precipitation tends to overestimate low latitude coastal areas and to be a missing value the polar side of the winter hemisphere from 40 degrees latitude due to the low temperature screening. In order to improve these problems, we separated the coast into the seaward and landward coasts, and reconsidered Rain/No-Rain classification method, screening conditions and estimation method of each algorithm.