亚洲季风建立及其中期振荡的高空环流特征

本文主要通过对100毫巴散度场、高度场和垂直积分的水汽输送场的分析,着重讨论了1979年整个亚洲季风区季风建立及其振荡中的高空环流特征。发现南亚高压周围不同部位的高空辐散场的建立导致了这些地区夏季风的建立,且南亚高压脊线中部和东部散度场具有不同的分布特点。从而使得印度季风有与长江流域梅雨同时开始而与华南雨季降水反位相的特点.在东亚,南亚高压外围东风对于夏季风的向北推进具有很好的指示性。在印度,伊朗高压(南亚高压环流的一部分)外围的东北气流对于印度季风的爆发具有指示性。100毫巴若干地区高度场和亚洲季风区域大范围水汽输送场的40—50天振荡清楚地显示出向东向北移动,而20—30天的散度场的振荡在印度季风爆发后则有系统地向西移动. 

ON FEATURES OF THE UPPER CIRCULATION IN THE ESTABLIS HMENT OF ASIAN MONSOON IN 1979 AND ITS MEDIUM-RANGE OSCILLATION

Based on analisis of 100mb divergence,geopotential height and vertically -integrated moisture transport fields a discussion is concentrated on features of the upper circulation in the establishment of Asian monsoon in 1979 and in its medium - range oscillation.It is found that the establishment of the high-level divergence fields in different parts around the South-Asian High(SAH)leads to the set-up of summer monsoon in these regions, the fields at the central and eastern sections of the SAH ridge fine have a distnctive characteristics that feature the concurrent onset of Indian monsoon and the Chang-Jiang valley Meiyu and the antiphase of the monsoon to the rainy-season precipitation in South China.In eastern Asia, the easterly around the SAH is a good indicator of the northward march of summer monsoon while in India the Iranian High north-easterly (being a component of the SAH circulation) in the outer brim is indicative of the Indian monsoon onset.100 mb height fields in some domains and vertically integrated moisture transport fields in 40-50 day oscillation exhibit propagation eastward and westward over the Asian area" whereas the 20-30 day oscillation of the divergence field moves regularly toward the west after the onset of Indian monsoon.