Analysis of the simulated different-class Meiyu precipitation and associated circulation by the BCC_AGCM2.0.1

Abstract

Based on the output data of Beijing Climate Center Atmospheric General Circulation Model version 2.0.1 (BCC_AGCM2.0.1), this study evaluates the simulated precipitation and associated circulation during the Meiyu period over the Yangtze-Huaihe River Basin (YHRB). The results show that BCC_AGCM2.0.1 can reasonably reproduce the spatial pattern of Meiyu over the YHRB. However, compared to the observation, the model underestimated (overestimated) the torrential and heavy (moderate and light) rainy days, indicating that the more (less) simulated light (torrential) rainy days result in more (less) modeled total rainy days (Meiyu precipitation amount). The simulated Meiyu onset begins in early June, earlier about 20 days than the climatological observation. For duration, Meiyu persists for 15 days, about 5 days shorter than the observation, which may be due to the simulated land-sea thermal contrast is earlier in early June. During the Meiyu period, the distribution patterns of the upper troposphere atmospheric circulation can be well simulated by BCC_AGCM2.0.1, but the obvious deficiency lies in the lower-troposphere air temperature and wind field, especially over Tibetan Plateau area.