夏季亚洲南部100毫巴流型的变化及其与西太平洋副热带高压进退的关系
THE 100-MB FLOW PATTERNS IN SOUTHERN ASIA IN SUMMER AND ITS RELATION TO THE ADVANCE AND RETREAT OF THE WEST-PACIFIC SUBTROPICAL ANTICYCLONE OVERTHE FAR EAST
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摘要: 通过对夏季亚洲南部100毫巴流型变化的研究,我们发现夏季我国西藏高原上空的反气旋是北半球副热带地区势力最强并稳定的大气活动中心。这个高空反气旋绕着其平均位置来回振动。在振动过程中,亚洲南部的100毫巴流型发生调整,并表现成两类基本的流型,其中第一类流型表现反气旋偏离高原,这时候在高原东西两侧(50°E和110°)各有新的反气旋建立,而在高原上则是低气压区;第二类流型表现在反气旋重新返回高原上空。在这两类流型转变期间,西太平洋副热带高压脊在中国大陆上出现一次进退过程,而且每年我国长江流域梅雨期的结束也与上述第一类流型的建立有联系。其次,我们对中国大陆上西太平洋副热带高压进退过程与100毫巴流型变化的关系进行了研究,发现两者关系甚密切。当100毫巴第一类流型出现时,西太平洋副热带高压北进西伸。而在第二类流型出现时,西太平洋副热带高压向东南撤退。根据这些关系并结合我国预报员有关副热带高压进退的预报经验,我们提出有关副热带高压进退预报的几个依据。Abstract: The 100mb Patterns in southern Asia in summer are investigated.It is found that the 100mb anticyclone over the Tibetan Plateau is a large and stable circulation feature in the subtropical region of the northern hemisphere,atad that it oscillates about its mean position.During its oscillation the West-Pacific subtropical anticyclone at 500 mb level shows a cycle of movement over the land of the Far East.When the 100mb anticyclone leaves the plateau,the West-Pacific subtropical anticyclone at 500 mb level advances to the land,while the 100mb anticyclone returns to the plateau,the West-Pacific anticyclone retreats from the land.This is a good criterion for forecasting the movement of West-Pacific anticyclone in summer.
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