Seasonal and interannual variations of surface climate elements over Vietnam

The 1991-2000 climate over Vietnam and the Indochina Peninsula is simulated using the Regional Climate Model version 3.0 (RegCM3). The domain of interest extends from 80E to 130E and 5S to 40N. The model is driven by the ERA-40 reanalysis data as initial and lateral boundary conditions, and is forced by the Optimum Interpolation Sea Surface Temperature (OISST) data over the oceans. Validations were carried out by comparing the simulated circulation fields, 2 m air temperatures, and precipitation to globally available observation data, and data from 50 meteorological stations over 7 sub-regions of Vietnam. In general, the simulated patterns of the interested fields are in good agreement with observed data. Although being somewhat wetter or dryer and cooler, RegCM3 reproduces relatively well the observed annual cycle and the inter-annual variability of surface air temperature and precipitation. A large proportion of the negative biases in temperature over Vietnam is explained by the lapse rate correction process. After correction for elevation differences, the model still underestimates air temperature over most of the sub-regions. In rainy and dry seasons, RegCM3 generally underestimates and overestimates precipitation, respectively.