A Regional Climate Model Nested in a Global Gridpoint General Circulation Model

Abstract

Abstract A ten‐year simulation of present climate over East Asia was conducted with the RegCM2 which is nested in a gridpoint general circulation model (IAP‐AGCM) developed by IAP/CAS (Institute of Atmospheric Physics, Chinese Academy of Sciences) in one‐way mode, and model results are tested and analyzed. It shows that the RegCM2 has a reasonable ability to simulate spatial distributions and seasonal cycles of surface air temperature and precipitation, due to its high resolution and perfect physics course. Compared with the IAP‐AGCM, the RegCM2 achieves much improvement. The spatial correlation coefficient (SCC) of annual surface air temperature increases from 0.92 to 0.94 and SCC of annual precipitation increases from 0.5 to 0.7 over China. One of the reasons is that the nested RegCM2 can capture mesoscale signals caused by sub‐GCM grid scale forcings, which exist in observations but not in the IAP‐AGCM.