ABILITY OF AN ENSEMBLE OF REGIONAL CLIMATE MODELS TO REPRODUCE SEASONAL PRECIPITATION AMOUNT OVER JAPAN REGION

Abstract

We analyzed results of three Regional Climate Models (RCMs) for 1984 to 2004 performed at 20-km horizontal grid spacing over Japan and the results of Japanese reanalysis data (JRA), and compared them with ground observations. Although JRA underestimated precipitation in Kochi Prefecture in the summer and in Niigata Prefecture in the winter, all the RCMs improved the underestimated precipitation in both prefectures. In addition, the skills of interannual variations in the three RCMs are superior to those in JRA. Futhermore, the skills of multi-model ensemble means, in particular, weighted multi-model ensemble means are distinctly superior to those of JRA on an interannual timescale. Thus, RCMs and their multi-model ensemble means are powerful tools for investigating interannual variations of future projections and seasonal predictions over Japan.