Abstract
Possible future changes in the elevation dependency of summertime precipitation over the Tibetan Plateau and the surrounding regions are investigated in time-slice ensemble experiments using a 60-km-mesh atmospheric general circulation model (AGCM). Four different lower boundary conditions in future climate simulations are synthesized based on World Climate Research Program/Coupled Model Intercomparison Project Phase-3 (WCRP/CMIP3) multi-model datasets. Simulated summer-time precipitation pattern in the present-day climate is compared with the observation based on rain-gauge-based gridded precipitation datasets. Precipitation is projected to increase in future climate simulations at high (above 4000 m) and low (1500 m or less) altitudes. These projected increases become more prominent with warmer prescribed global mean sea surface temperatures. Analysis of the elevation dependency of the atmospheric water budget indicates that projected future precipitation increases at high altitudes are caused by increases of evaporation from the surface of the Tibetan Plateau. These increases in surface evaporation are accompanied by increases in surface air temperature and snow-free area at high altitudes, suggesting that the snow/ice albedo feedback is a key component of future climate change over the Tibetan Plateau.
