Performance of convective parameterization schemes in Asia using RegCM: Simulations in three typical regions for the period 1998–2002

Abstract

This study discusses the sensitivity of convective parameterization schemes (CPSs) in the Regional Climate Model (version 4.3) (RegCM4.3) over East/South Asia. The simulations using different CPSs in RegCM are compared to discover a suitable scheme for this region, as the performance of different schemes is greatly influenced by region and seasonality. Over Southeast China and the Bay of Bengal, the Grell scheme exhibits the lowest RMSEs of summer precipitation compared to observed data. Moreover, the Emanuel over land and Grell over ocean (ELGO) scheme enhances the simulation, in comparison with any single CPS (Grell/Emanuel) over Western Ghats, Sri Lanka, and Southeast India. Over the Huang-Huai-Hai Plain (3H) and Tibetan Plateau (TP) regions of China, the Tiedtke scheme simulates the more reasonable summer precipitation with high correlation coefficient and comparable amplitude. Especially, it reproduces a minimum convective precipitation bias of 8 mm d−1 and the lowest RMSEs throughout the year over East/South Asia. Furthermore, for seasonal variation of precipitation, the Tiedtke scheme results are closer to the observed data over the 3H and TP regions. However, none of the CPSs is able to simulate the seasonal variation over North Pakistan (NP). In comparison with previous research, the results of this study support the Grell scheme over South Asia. However, the Tiedtke scheme shows superiority for the 3H, TP and NP regions. The thicker PBL, less surface latent heat flux, the unique ability of deep convection and the entrainment process in the Tiedtke scheme are responsible for reducing the wet bias.