The Role of Land-sea Distribution and Orography in the Asian Monsoon. Part II： Orography  

作　　者：XU Zhongfeng QIAN Yongfu FU Congbin 

机构地区：[1]School of Atmospheric Sciences, Nanjing University, Nanjing 210093 [2]RCE-TEA, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029

出　　处：《Advances in Atmospheric Sciences》2010年第3期528-542,共15页大气科学进展（英文版）

基　　金：Acknowledgements. The authors would like to thank the anonymous reviewers for their valuable comments and suggestions. This research is supported jointly by the ＂National Key Developing Programme for Basic Science＂ project 2006CB400500, National Natural Science Foundation of China General Program Grant Nos. 40905042 and 40675042, and China Postdoctoral Science Foundation Grant No. 20070410133.

摘　　要：The role of various mountains in the Asian monsoon system is investigated by AGCM simulations with different mountains. The comparison of the simulation with Asian mountains （MAsia run） with the simulation without mountains （NM run） reveals that the presence of the Asian mountains results in a stronger South Asian summer monsoon （SASM）, characterized by enhanced lower-tropospheric westerly winds, uppertropospheric easterly winds, and stronger water vapor convergence. In East Asia, the southerly winds and water vapor convergence are significantly strengthened in association with the intensified zonal pressure gradient between the East Asian continent and the Pacific Ocean. Both the dynamical and thermodynamic forcing of the Tibetan Plateau play important role in strengthening the Asian summer monsoon. In winter, the presence of Asian mountains significantly strengthens the continental high, which leads to a stronger Asian winter monsoon. The presence of African-Arabian mountains helps to intensify the exchange of mass between the Southern Hemisphere and Northern Hemisphere by strengthening the cross equatorial flows in the lower and upper troposphere over East Africa. Asian mountains also play a crucial role in the seasonal evolution of Asian monsoons. In comparison with the NM run, the earlier onset and later withdrawal of lower-tropospheric westerly winds can be found over South Asia in the MAsia run, indicating a longer SASM period. The African-Arabian mountains also moderately contribute to the seasonal variation of the South Asian monsoon. In East Asia, the clear southto-north march of the southerly winds and subtropical rainfall starts to occur in early summer when the effects of Asian mountains are considered.The role of various mountains in the Asian monsoon system is investigated by AGCM simulations with different mountains. The comparison of the simulation with Asian mountains （MAsia run） with the simulation without mountains （NM run） reveals that the presence of the Asian mountains results in a stronger South Asian summer monsoon （SASM）, characterized by enhanced lower-tropospheric westerly winds, uppertropospheric easterly winds, and stronger water vapor convergence. In East Asia, the southerly winds and water vapor convergence are significantly strengthened in association with the intensified zonal pressure gradient between the East Asian continent and the Pacific Ocean. Both the dynamical and thermodynamic forcing of the Tibetan Plateau play important role in strengthening the Asian summer monsoon. In winter, the presence of Asian mountains significantly strengthens the continental high, which leads to a stronger Asian winter monsoon. The presence of African-Arabian mountains helps to intensify the exchange of mass between the Southern Hemisphere and Northern Hemisphere by strengthening the cross equatorial flows in the lower and upper troposphere over East Africa. Asian mountains also play a crucial role in the seasonal evolution of Asian monsoons. In comparison with the NM run, the earlier onset and later withdrawal of lower-tropospheric westerly winds can be found over South Asia in the MAsia run, indicating a longer SASM period. The African-Arabian mountains also moderately contribute to the seasonal variation of the South Asian monsoon. In East Asia, the clear southto-north march of the southerly winds and subtropical rainfall starts to occur in early summer when the effects of Asian mountains are considered.

关 键 词：MOUNTAINS Asian monsoon RAINFALL seasonal transition 

分 类 号：P425.42[天文地球—大气科学及气象学] P458.121.1