【摘要】 作者分析了1951—55时期中850、700及500毫巴的7月平均气流场的构造,以及1956年7、8两月亚洲上空200毫巴平均等高线图.又作了1956年7、8两月东经75度、90度、105度和120度经线上平均风场和温度场的剖面.我们发现,在夏季有三种基本气流组成亚洲大陆上空三度空间的气流场:即,(1)中纬度的西风气流,(2)高空热带和副热带的东风气流,(3)位于高空热带和副热带东风气流下面的西南季风.此外,对于1956年从春季到夏季的过渡时期中,亚洲上空大气环流的转变,亦作了研究.我们发现,从春季到夏季的过渡时期中,亚洲上空的大气环流有着一个跳躍的转变.在这个时期中,喜马拉雅山南边的高空副热带西风急流向北撤退,在西藏高原的纬度上空,建立一个副热带高压脊线,并且在亚洲南部上空(北纬12度以南)建立一支高空东空急流.同时印度的西南季风和我国长江流域的梅雨时期开始出现.作者又发现,夏季在中国大陆上,雨带的北移和西风带北撤以及相应的西风带强度的削弱有着密切的联系.更多还原

【Abstract】 In this paper,an analysis is made on the structure of the July meanflow field at 850 mb,700 mb,500 mb over the continent of Asia during theyear 1951—1955 and the mean contours at 200 mb over Asia for July andAugust,1956.The vertical cross-sections of the mean flow and temperaturefields along 75°E,90°E,105°E and 120°E for July and August,1956 havebeen constructed.The three-dimensional flow structure over continent ofAsia is constituted of the following three basic currents:(1) the westerliesof middle latitudes,(2) the upper level tropical and subtropical esterlies,and (3) the south-westerly monsoon under the upper level tropical andsubtropical easterlies.Moreover,the changes of the general circulation over Asia in thetransitional period between spring and summer,1956 is also investigated.It is found that a leaping change of the general circulation over Asiaoccurs during this period.The upper level subtropical ridge was establis-hed over the latitude of Tibet,and over south Asia (to the south of 12°N)an high level easterly jet-stream was established.At the same time,thesouth-westerly monsoon of India and the “Meiyu” (plum rain) season ofthe Yangtze valley set in.The authors also found that the northwarddisplacement of the rain belt is closely related to the northward retreatand the accompanying weakening in intensity of the westerlies over Chinamain land.更多还原