Inter-comparison and evaluation of mixed-convection schemes in RegCM4 for Indian summer monsoon simulation

The MCSs having Tiedtke/Emanuel scheme over the land and the Grell scheme over the ocean (L:Ti_O:Gr; L:Em_O:Gr) are found qualitatively and quantitatively better to simulating the semi-permanent characteristics of the ISM. These MCSs are effectual in predicting seasonal mean precipitation intensity and distribution during the ISM and closer to IMD precipitation analysis than any other MCSs. It is found that the MCS having Grell scheme over the land and ocean, spatial gradient of precipitation is reasonably well when compared to IMD precipitation analysis. The representation of precipitation over the central India is poor in all the MCSs; this is probably due to increased cloud cover in RegCM4 which in turn, leads to reducing surface air temperature over land and thus reduce convective instability in the model simulations. The present study proposes a statistically based screening method to identify the useful MCSs that have reasonable skills. The best performing MCSs examined for normal and deficit monsoon years are used to simulate 15 consecutive monsoon seasons (1982-1996). Simulations of several monsoon years confirm that the two MCSs namely L:Ti_O:Gr and L:Em_O:Gr are suitable to simulate the ISM.