Hindcast experiment of extraseasonal short-term summer climate prediction over China with RegCM3_IAP9LAGCM.

The regional climate model RegCM3 has been one-way nested into IAP9L-AGCM, the nine-level atmospheric general circulation model of the Institute of Atmospheric Physics, Chinese Academy of Sciences, to perform a 20 year (1982-2001) hindcast experiment on extraseaonal short-term prediction of China summer climate. The nested prediction system is referred to as RegCM3_IAP9LAGCM in this paper. The results show that hindcasted climate fields such as 500 hPa geopotential height, 200 and 850 hPa zonal winds from RegCM3_IAP9L-AGCM have positive anomaly correlation coefficients (ACC) with the observations, and are better than those from the standalone IAP9L-AGCM. Except for the 850 hPa wind field, the positive ACC of the other two fields with observations both pass the 90% confidence level and display a zonal distribution. The results indicate that the positive correlation of summer precipitation anomaly percentage between the nested prediction system and observations covers most parts of China except for downstream of the Yangtze River and north of Northeast and Northwest China. The nested prediction system and the IAP9LAGCM exhibit different hindcast skills over different regions of China, and the former demonstrates a higher skill over South China than the latter in predicting the summer precipitation.