青藏高原影响亚洲夏季气候研究的最新进展

RECENT PROGRESS IN THE STUDY ON THE IMPACTS OF TIBETAN PLATEAU ON ASIAN SUMMER CLIMATE

  • 摘要: 文中回顾了近10a来吴国雄等在青藏高原影响亚洲夏季气候研究方面的最新进展。通过分析东西风交界面的演变证明,由于青藏高原的春季加热,亚洲季风区对流层低层冬季盛行偏东风转变为夏季偏西南风最早发生在孟加拉湾东部,与其相伴随的激烈对流降水出现在其东面。因此孟加拉湾东部至中印半岛西部是亚洲季风最早爆发的地区。同时也指出盛夏伊朗高原和青藏高原加热所激发的同相环流嵌套在欧亚大陆尺度的热力环流中,从而加强了东亚的夏季风,加剧了中西亚的干旱;并通过其所激发的波动对夏季东亚的气候格局产生重要影响。文中还比较了夏季南亚高压的伊朗模态和青藏模态性质的异同及其对亚洲夏季降水异常分布的不同影响。

     

    Abstract: The recent progresses in the study of the impacts of Tibetan Plateau on Asian summer climate in the last decade are reported. By analyzing the evolution of the interface between westerly to the north and easterly to the south (WEB), it is shown that due to the strong heating over Tibetan Plateau in spring, the overturning in the prevailing wind direction from easterly in winter to westerly in summer occurs firstly over the eastern Bay of Bengal (BOB), accompanied with vigorous convective precipitation to its east. The area between East BOB and western Indochina Peninsula thus becomes the area of the earliest Asian monsoon onset, which is referred as BOB monsoon in short. It is shown that the summertime circulations friggered by the thermal forcing of Iran Plateau and Tibetan Plateau are embedded in phase with the continental-scale circulat ion forced by the diabatic heating over the Eurasian Continent. As a result the East Asian summer monsoon is intensified and the droaught climate over the west ern and central Asian areas is enhanced. These together with the perturbations friggered by the Plateau and associated heating exert important influences on the climate patterns over Asia. Furthermore the charact eristics of the Tibetan mode of the summert ime South Asian High are compared with those of Iran mode. Results demonstrate that corresponding to each of the bimodality of the South Asian High, the rainfall anomaly distributions over Asia possess different pat terns.

     

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