The role of land-sea distribution and orography in the Asian monsoon. Part II: Orography
The role of land-sea distribution and orography in the Asian monsoon. Part II: Orography
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DOI：
10.1007/s00376-009-9045-z
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发表时间：
2010-04
影响因子：
5.8
通讯作者：
Zhongfeng Xu;Y. Qian;C. Fu
中科院分区：
文献类型：
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作者：
Zhongfeng Xu;Y. Qian;C. Fu
利用不同山脉的AGCM模拟，研究了不同山脉在亚洲季风系统中的作用。对比有亚洲山脉的模拟（MAsia运行）和无山脉的模拟（NM运行）发现，亚洲山脉的存在导致南亚夏季风（SASM）增强，其特征是对流层下部西风增强，对流层上部东风增强，水汽辐合增强。在东亚地区，偏南风和水汽辐合明显加强，这与东亚大陆和太平洋之间的纬向气压梯度增强有关。青藏高原的动力强迫和热力强迫对亚洲夏季风的加强起着重要作用。在冬季，亚洲山脉的存在显着加强了大陆高压，这导致了更强的亚洲冬季风。非洲-阿拉伯山脉的存在通过加强东非地区对流层上下层的越赤道气流，加强了南、北方半球的物质交换，亚洲山脉对亚洲季风的季节演变也起着重要作用。与NM运行相比，在MAsia运行中，南亚地区对流层低层西风的出现时间较早，消失时间较晚，表明SASM周期较长。非洲-阿拉伯山脉对南亚季风的季节变化也有一定的贡献。在东亚，当考虑亚洲山脉的影响时，南风和副热带降雨的明显南向北行进开始于初夏。
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, upper-tropospheric 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 south-to-north march of the southerly winds and subtropical rainfall starts to occur in early summer when the effects of Asian mountains are considered.