东亚寒潮冷空气的传播和行星尺度作用
The Propagation of the Winter Monsoon During Clod Air Outbreaks in East Asia and the Associated Planetary-scale Effect
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摘要: 本文研究了1980—1984年冬季19次东亚寒潮爆发过程中低频扰动的传播特征和行星尺度作用。揭示出冷空气的向南传播主要是一种低频模态的10—20天周期的振荡。另一方面,与寒潮爆发有关的西伯利亚冷高压作为北半球冬季对流层的主要冷源会导致一系列行星尺度过程的响应。这主要表现为辐散环流的上升支迅速地从印尼—马来西亚地区东移到东太平洋,使正常的沃克环流反向。这种情况十分相似于由非厄尔尼诺年到厄尔尼诺年辐散环流的运动。从动力学上,这种辐散环流有利于东太平洋以及北美西岸的天气发展。Abstract: The present paper has delt with the characteristics of propagation of the winter monsoon during cold air outbreaks for 19 cases of 1980—1984 in East Asia as well as the associated planetary-scale effect. It has been revealed that the propagation of cold air mainly shows a mode of 10—20 day period oscillation. Furthermore, the Siberian cold high associated with outbreaks of cold air may lead to the response of a chain of planetary-scale events. This mainly shows up in the fact that the branch of upward motion of the divergent circulation rapidly shifts from the Indonesia-Malaysian region eastward to the eastern Pacific, thus causing the normal-type Walker circulation to reverse its sense. This condition is very similar to the movement of divergent circulation from non-El Nino year to El Nino year. From the dynamic viewpoint, this kind of divergent circulation is favorable to the synoptic development over the eastern Pacific and the western coast of North America.
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