Performance of convection schemes on the simulation of summer monsoon features over the South Asia CORDEX domain using RegCM-4.3

摘要

An endeavour is made to investigate the performance of convective parameterization schemes on the simulation of South Asian summer monsoon features through a regional climate model (RegCM). For this purpose, RegCM version 4.3 developed by International Center for Theoretical Physics (ICTP) is used for the simulation experiments in the Coordinated Regional Climate Downscaling Experiment (CORDEX) framework over the South Asia domain. Four convective schemes, namely, Emanuel, Grell, Tiedtke and a mixed scheme (Emanuel over land and Grell over the ocean) are evaluated in RegCM4.3 at 45 km horizontal resolution. The simulated results of precipitation, temperature and wind fields are systematically evaluated respectively with Tropical Rainfall Measurement Mission (TRMM), Climate Research Unit (CRU) and ECMWF re-analysis (ERA) Interim datasets. The results reveal that the response of a mixed convective scheme is better in simulating precipitation and temperature realistically over the Indian subcontinent and is in close agreement with the TRMM observations, compared with the three other schemes. The circulation features are also properly represented with the mixed convection scheme. Furthermore, the annual cycle of precipitation and temperature averaged over the Indian region are well estimated in the mixed scheme, compared with the CRU observations. The northward propagation of monsoon intra-seasonal oscillations in extreme monsoon seasons is simulated reasonably in a mixed convection scheme as compared with three other schemes. The inter-annual variability of area averaged JJAS precipitation over the Indian region is simulated well by the model for the combination of Emanuel over land and Grell over the ocean. Grell scheme overestimates the JJAS precipitation, whereas Emanual and Tiedtke schemes underestimate