夏季东亚热带和副热带地区经向和纬向环流型的特征
THE CHARACTERISTICS OF THE ZONAL AND MERIDIONAL CIRCULATION OVER TROPICAL AND SUBTROPICAL REGIONS IN EASTERN ASIA IN SUMMER
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摘要: 根据1958年7月8-18日和1957年7月21-30日东亚低纬度的两个悬殊的环流型,分析了在这两个时期内东亚低纬度环流的各种特征。结果得出,在经向和纬向环流期间,无论北半球纬向风带的位置,长波系统的配置,副热带高压活动的情况以及赤道辐合区的分布都有着很大的不同。此外,台风活动的次数也表现有很大悬殊。其所以有如此悬殊,可以从该两时期低纬度流场的特点来说明原因。在中国大陆上,在这两个时期的天气过程也很不同,在经向环流期间,大陆上的主要雨带成东北-西南向的,而在纬向环流期间,雨带便成东西向分布,并集中在江淮流域之间。另外,我们又研究了在这两个时期内南北半球间环流关系,从手头所掌握的资料分析结果看,两者关系相当密切。在东亚低纬度经向环流期间,南半球(特别在澳洲)也盛行经向环流,并且在澳洲附近从南半球向北半球的质量输送也最强烈;而在东亚低纬度纬向环流期间,南半球也盛行纬向环流,澳洲附近的冷空气活动不显著,越过赤道向北的质量输送也比较弱。Abstract: In this paper,an analysis is made on two main distinct flow patterns over the tropical and subtropical area in Asia and on its adiacent water.They occur respectively in the periods of July 8-18,1958 and July 21-30,1957.It is found that during these two periods there is marked difference in the characteristics of the tropospheric circulations.The position of zonal wind belt over the northern hemisphere,the distribution of long wave patterns,the activity of subtropical highs,and the distribution of the intertropical convergence zone are all quite different.At the same time,the activity of typhoons and other synoptic processes over the continent are also dfferent.In addition,we found that thcre are some interactions between the northcrn and the southern hemisphere.When low index circulation prevails over subtropics and tropics in Eastern Asia,there is meridional circulation in the southern hemisphere(cspecially in Australia),and there is a mass transport from the southern to northern hemisphere.While high index circulation prevails over northern hemisphere,zonal flow pattern prevails in the southern hemisphere.