Simulation of summer climate over East China by convection-permitting regional air-sea coupled model

In this research, the Coupled-Ocean-Atmosphere-Wave-Sediment Transport (COAWST) Model was utilized to study the summer climate over eastern China and its adjacent ocean from 2009 to 2018. The COAWST model, equipped with a convection-permitting resolution of approximately 4km, effectively replicated the patterns of precipitation for both land and ocean, including sub-daily extreme precipitation, and the diurnal cycle. The COAWST model offers accurate simulations of the land-sea contrast in terms of the diurnal cycle of precipitation, showing the peaks of rainfall over land and sea in the afternoon and morning respectively. The model exhibited higher skill in extreme precipitation intensity over the ocean, while it was more skillful in wet frequency over the land. The overestimation of land precipitation can be attributed to stronger water vapor flux convergence and latent heat flux in the model. The inclusion of ocean module affects the ocean condition through fresh water injection, which contribute to the sea surface temperature (SST) bias in the simulation. This article highlights the strong performance of the coupled atmosphere-ocean model in simulating coastal precipitation of eastern China.