Sensitivity of regional climate simulations to land-surface schemes on the Tibetan Plateau

Abstract

To investigate the effects of land-surface schemes in 2 regional climate models (RegCM3 and RegCM4.3.4) on the Tibetan Plateau (TP) climate simulation, 3 groups of 10 yr (1992-2001) simulation experiments were performed based on 2 land-surface schemes (BATS and CLM3.5). The simulations (RegCM3_BATS, RegCM4_BATS, and RegCM4_CLM) were compared with observed data by setting the same domain and initial and lateral atmospheric boundary conditions and using 30 km spatial resolution. The results showed that, compared to observed data, regional average annual mean temperature was underestimated by 1.22, 2.11, and 1.32 degrees C, and regional average annual precipitation was overestimated by 43.2, 49.8, and 18.4% in RegCM3_BATS, RegCM4_BATS, and RegCM4_CLM respectively. There were significant differences in simulated energy and water budget components among the 3 models resulting from the influence of the 2 different land-surface parameterization schemes, which impacted the simulated precipitation and temperature results through interaction between the land surface and the atmosphere. Therefore, climate simulation over the TP is very sensitive to the use of different land-surface schemes in regional climate models. Overall, use of RegCM4_CLM instead of RegCM_BATS resulted in a warmer and drier land surface and a better simulation of annual average spatial patterns of temperature and precipitation.