Characteristics of an East-Asian summer monsoon climatology simulated by the RegCM3

We investigated the characteristics of a 22-year-long regional climatology of the East Asian summer monsoon (EASM) simulated by the Regional Climate Model version 3 (RegCM3). The RegCM3 was forced by the perfect boundary conditions, i.e., the National Centers for Environmental Prediction (NCEP)/Department of Energy (DOE) reanalysis (R-2), for summer (June-July-August, JJA) during the period of 1982-2003 with a 60km horizontal resolution. This study stresses the evaluation of the seasonal mean climatology and interannual variations against the R-2 as well as a shorter time-scale variation, such as intraseasonal and diurnal variations over the Korean Peninsula, against the station-observed datasets. The RegCM3 is able to reproduce overall features of the seasonal mean climatology with a wet bias of 0.54 mm day(-1) and a certain cold (warm) bias in the lower (upper) troposphere. Interannual variability during the 22 years also shows good agreement with the R-2 reanalysis, both in precipitation and temperature. The capability of the RegCM3 in reproducing intraseasonal variability is reasonable in terms of a 22-year-long climatology. The daily variations of the simulated climatology in surface temperature and in precipitation over Korea are also reasonably reproduced during June and July but are relatively poorly resolved for August. The skill degradation is clearer in the last eight years of 1996-2003 than the first period of 1982-1989, which raises an issue of the RegCM3's ability to capture the observed decadal change in the mid-1990s. Diurnal variations of surface climate simulated by the model exhibit overestimated (underestimated) amplitudes in precipitation (temperature).