Abstract Submission: How often does annual extreme precipitation, which is said to occur once every 100 years, occur in Japan? To answer this question, the purpose of this study is to analyze the spatial return period of extreme precipitation in all cells in Japan. The spatial return period is defined as "the period until the extreme precipitation occurs again in the specific area". We used the d4PDF with a spatial resolution of 20 km to analyze the large-scale ensemble data of thousands of years, which cannot be obtained from the observed precipitation data. Four probability distribution functions, which are GEV, Gumbel, Weibull, and Log-normal, are checked to obtain the best-fit function using SLSC. Then, GEV shows the best with less than 0.04 about SLSC in 97% area of Japan. The spatial return period of the 100-year extreme precipitation over Japan is 1.18 years in the historical simulation and 1.00 years in the +4-K future simulation. We clarified the relationship between the annual precipitation occurrence area of RP100-year extreme precipitation and its probability. The average area of occurrence of RP100-year annual extreme daily precipitation was averaged for each area during the data period. The mean area of RP100-year is 15,900 km for the + 4-K simulation. The average value obtained from the precipitation data of 3000 years, and the RP100-year annual extreme daily precipitation occurrence area varied from year to year.
