Simulation Contrast of Different Cloud Parameterization Schemes for the Extremely Severe Torrential Rainfall Event in Beijing on 21 July 2012
Four cumulus convection parameterization schemes, i.e., the KainFritsch (KF), BettsMillerJanjic (BMJ), GrellDevenyi (GD) and Simplified ArakawaSchubert (SAS) schemes in the weather research and forecasting modeling system (WRF V3.5.1 version) are respectively used to simulate the severe torrential rain event in Beijing during 21-22 July 2012, particularly focusing on spatiotemporal features of convection bursts, and the impact factors of precipitation forecast. The results show that the simulated rainfall location and intensity by the KF scheme agree well with the observation while the BMJ scheme exaggerates the scope and intensity of the severe rainfall. The GD and SAS schemes have poor simulation results. The initial burst states and evoluting process of convection in the four schemes are quite different, and the forecast time is also different. Generally speaking, KF scheme performs better in simulating convection burst and it can simulate a strong upward motion and abundant moisture during the severe torrential rain period. Meanwhile, the rainfall rates in the simulated deep convection area are relatively high with KF and BMJ schemes. However, the simulated precipitation by SAS scheme is dominated by the stratus cloud area and it is unable to work out the center of the severe rainfall.