Sensitivity of the WRF Model Simulation of the East Asian Summer Monsoon in 1993 to Shortwave Radiation Schemes and Ozone Absorption

Sensitivity of the Weather Research and Forecasting (WRF) model simulation of the East Asian summer monsoon (EASM) in 1993 to solar radiation parameterizations and ozone absorption was investigated. Three numerical experiments were conducted using the National Centers for Environmental Prediction/Department of Energy (NCEP/DOE) and the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis data as time-varying surface and lateral boundary forcings, respectively: (a) a control run (CTL) with the Dudhia radiation scheme and the model top placed at 50 hPa, (b) the SWG experiment which is the same as the CTL except the Goddard radiation scheme, and (3) the SWT run which is the same as the SWG but the model top was raised to 5 hPa and the vertical levels increased from 31 to 35. The use of the Goddard scheme results in considerable improvement in reproducing the model's thermal structures, such as zonal mean air temperature, its latitudinal gradient and vertically integrated temperature. This leads to better agreements in the simulation of the upper tropospheric zonal winds through the thermal wind relationship which, in turn, rectifies the low-level circulations through dynamical coupling between the upper and lower troposphere. The Taylor diagram analysis quantitatively indicates that the SWT and the SWG are discernable from each other with slightly improved simulations in the SWT. This suggests a nontrivial role of ozone absorption and accompanied stratospheric heating in EASM simulation.