东亚季风气侯对青藏高原隆升的敏感性研究

Sensitivity of the East Asian Monsoon Climate to the Tibetan Plateau Uplift

青藏高原隆起是东亚季风形成演化的决定因子之一。利用ＧＣＭ（大气环流模式）完成的一系列改变青藏高原地形高度的数值试验说明，东亚季风气候变化非常敏感地响应于高原隆升。在高原隆升达到现代高度的一半之前，东亚大约３０°Ｎ以北地区近地面冬夏反向意义下的季风现象是不存在的。高原隆升对东亚冬季风的影响远大于对夏季风的影响。即使没有青藏高原，仅受海陆热力对比的作用，中国东部地区夏季已能出现偏南风；然而只有在青藏高原存在，且达到一定高度的情况下，东亚北方地区冬季才能盛行偏北风。从温湿状况看，大约长江以北的东亚北方季风强度随高原高度上升几乎呈线性增加，冬夏温度对比不断加大，降水也越来越向夏季集中。但长江以南的东亚南方季风和印度季风与此明显不同，前者对高原隆升具有非线性响应，而后者在高原隆升过程中变化不大。

This paper systematically investigates sensitivity of the East Asian monsoon climate to the Tibetan Plateau uplift by using an atmospheric general circulation model (GCM). A series of numerical experiments with changed topography heights in the Tibetan area show that the East Asian mohsoon climate has a strong response to the uplift of the Tibetan Plateau. There would be no monsoon. a phenomenon of an alternation between dominant surface winds with opposite directions in winter and in summer. over the East Asia to the north of 30°N if the plateatl were below the half of its present height. The orographic influence on the winter monsoon is greater than that on the summer one. Surface south wind can appear over the eastern China in summer even without the Tibetan Plateau. However. surf'ilce north wind prevails in winter only if the plateau rises to a critical height. According to surface air tem- perature and humidity. the monsoon intensity of the area to the north of the Yangtze River almost linearly increases. the temperaturn contrast between summer and winter enlarges and the annual precipitation concentrates towards' summer season along with the unceasing upheaval of the plateau. Nevertheless. monsoon changes on the area to the south of the Yangtze River and india are different. The monsoon has a nonlinear response to the plateau uplift over the East Asia to the south of the Yangtze River but little response over India.