Asynchronous responses of East Asian and Indian summer monsoons to mountain uplift shown by regional climate modelling experiments
Asynchronous responses of East Asian and Indian summer monsoons to mountain uplift shown by regional climate modelling experiments
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DOI：
10.1007/s00382-012-1603-x
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发表时间：
2013-03
期刊：
影响因子：
4.6
通讯作者：
Hui Tang;A. Micheels;J. Eronen;B. Ahrens;M. Fortelius
中科院分区：
文献类型：
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作者：
Hui Tang;A. Micheels;J. Eronen;B. Ahrens;M. Fortelius
气候模式已经证明，印度和东亚夏季风(ISM和EASM)都因整个亚洲地形或青藏高原(TP)的隆起(即大范围的山体隆起)而得到加强。这种影响被广泛认为是导致亚洲夏季风在新近纪演变的主要机制。然而，地质证据表明，亚洲地形(即区域山体隆起)的历时增长比整体山体隆起更多。这就要求重新评价地质时期山体隆升与亚洲季风的关系。本文利用区域气候模式COSMO-CLM进行了考虑亚洲地形不同区域的历时增长的敏感性试验，以研究它们对亚洲夏季风的影响。结果表明，与块状山体隆起不同，区域性山体隆起可导致ISM和EASM的非同步发展。ISM主要由南部TP(Zagros Mountain)的隔热(机械阻塞)作用加强，而EASM则主要由TP中部、北部和东部的地面感热加强。这种地面加热可以在对流层周围引起低层气旋性异常，通过抑制对流层低层季风涡度来减少ISM，但通过加强来自TP南部的暖平流来促进EASM，从而维持季风对流。我们的发现为亚洲夏季风的演化及其与新近纪构造变化的相互作用提供了新的见解。
It has been demonstrated in climate models that both the Indian and East Asian summer monsoons (ISM and EASM) are strengthened by the uplift of the entire Asian orography or Tibetan Plateau (TP) (i.e. bulk mountain uplift). Such an effect is widely perceived as the major mechanism contributing to the evolution of Asian summer monsoons in the Neogene. However, geological evidence suggests more diachronous growth of the Asian orography (i.e. regional mountain uplift) than bulk mountain uplift. This demands a re-evaluation of the relation between mountain uplift and the Asian monsoon in the geological periods. In this study, sensitivity experiments considering the diachronous growth of different parts of the Asian orography are performed using the regional climate model COSMO-CLM to investigate their effects on the Asian summer monsoons. The results show that, different from the bulk mountain uplift, the regional mountain uplift can lead to an asynchronous development of the ISM and EASM. While the ISM is primarily intensified by the thermal insulation (mechanical blocking) effect of the southern TP (Zagros Mountains), the EASM is mainly enhanced by the surface sensible heating of the central, northern and eastern TP. Such elevated surface heating can induce a low-level cyclonic anomaly around the TP that reduces the ISM by suppressing the lower tropospheric monsoon vorticity, but promotes the EASM by strengthening the warm advection from the south of the TP that sustains the monsoon convection. Our findings provide new insights to the evolution of the Asian summer monsoons and their interaction with the tectonic changes in the Neogene.