Comparison of Clm 4.5 and Bats Land-Surface Scheme in Regional Climate Model for Climate Projection Baseline in Indonesia: a Sensitivity Study

The Regional Climate Model (RegCM4) was customized for 10-year climate simulation over Indonesia region through sensitivity studies on ocean fluxes and land surface parameterization schemes. The model was configured over 90.875 E 149.125 E and 13.125 S 9.375 N at 25-km horizontal resolution with 18 vertical levels. Three 10-year (19932002) simulations were conducted with the combinations of two land surface schemes (Biosphere-Atmosphere Transfer Scheme (BATS) and Community Land Model 4.5 (CLM4.5)), one cumulus convection schemes (the Massachusetts Institute of Technology (MIT)) and two ocean fluxes schemes (Zeng, Monin-Obukhov). The simulated seasonal climatology of surface temperature and precipitation were compared with dataset from the Climate Research Unit (CRU) and Tropical Rainfall Measuring Missions (TRMM) observations. Over most land areas, RegCM4 surface air temperatures were higher than reanalysis forcing data by 1 to 4C. The model could realistically simulate the seasonal climatology of winds. The results indicated that the model simulated climatology was sensitive to the ocean fluxes as well as land surface parameterization. Used of the CLM4.5 instead of BATS resulted in a warmer and drier land surface and a better simulation of the seasonal average spatial pattern of precipitation and temperature. Keywords: RegCM4, Ocean Fluxes, Land Surface, MIT, BATS, CLM 4.5