Impacts of Cumulus Convective Parameterization Schemes on Simulation of East Asian Summer Circulation and Rainfall

Two experiments have been conducted using WRF (Weather Research and Forecasting) model with different cumulus convective parameterization schemes in this paper. It is found that the model with the Kain-Fritsch (KF) scheme performs well for the simulation of summertime large scale circulation over East Asia, and the evolution/withdrawal of the rain belt and the spatial pattern are close to that retrieved from TRMM, although precipitation is overestimated in the simulation. With the Grell-Freitas (GF) scheme, however, there exist obvious biases in the simulation of precipitation and circulation. The possible reason for these biases is that the convective heating rate is overestimated with the GF scheme, which results in abnormally strong convection in the South China Sea-Philippine area and the diabatic heating is overestimated. As a result, the divergence on the southern side of the western Pacific subtropical high is weakened, which may inhibit the northward and westward extension of the subtropical high and influence water vapor transport and monsoon circulation as well as the summer climate in East Asia. It is also found that the simulation of large scale circulation can be improved in the sensitivity experiment by decreasing the convective heating rate and drying rate in the GF scheme.