Reproducibility of Regional-Mean Probable Precipitation by High-Resolution Climate Models

We assessed the reproducibility of regional-mean probable precipitation in Japan estimated based on the results of three runs of a 20km-mesh global climate model (MRI-GCM20) and one run of a 20km-mesh regional climate model (MRI-RCM20). These models inappropriately simulate the annual maximum daily precipitation at individual grid points, especially in relation to the spatial pattern, but estimate the regional mean reasonably well. MRI-GCM20 runs simulated data over annual maximum regional-mean 10-day precipitation better than 1-day. Precipitation and return values estimated by MRI-GCM20 were quite different from those by MRI-RCM20. Among the three MRI-GCM20 runs, one forced by SST without year-to-year variability estimated the standard deviation of the annual maximum precipitation as smaller than those forced by SST with year-to-year variability. The reproducibility of the average and standard deviation of the annual maximum precipitation is correlated with the reproducibility of 30-year return values.