Sensitivity of East Asian monsoon climate to the uplift of the Tibetan Plateau

Using the COLA (Center for Ocean-Land-Atmosphere Studies) general circulation model, a series of numerical experiments were conducted to examine the impact of uplift of the Tibetan Plateau on the evolution of the monsoon climate in East Asia. An attempt was made to isolate the effect of the Plateau uplift from the changes in other forcing mechanisms. We examined the spatial and temporal variation patterns of a variety of climatic variables and indices, including monsoon intensity, sea level pressure, surface and upper-air winds, temperature at different levels, precipitation, air humidity and soil moisture. Our results suggest that the evolution of the East Asia monsoon may be more sensitive to the uplift of the Tibetan Plateau than that of the South Asia monsoon. Moreover, the effect of the Plateau uplift on the East Asia winter monsoon is more significant than that on the summer monsoon. In the northern part of East Asia (North China), the formation of the monsoon climate is marked mainly by the establishment of the northerly winds in winter, or the winter monsoon system, corresponding to the uplift of the Plateau when the height reaches approximately 50% of its current elevation. On the other hand, the establishment of the monsoon climate in the southern part of East Asia (the Yangtze River valley and the area south of it) may be much earlier than that in the northern part.