A Study of the Coupling Effect of Stratospheric and Tropospheric Circulations in Early Summer, 1979

Abstract

For the past 30 years, much effort has been made by Chinese meteorologists in the investigation of such medium- and long-term weather processes as the pre-flooding season of South China, the Meiyu over the middle and lower reach of the Changjiang River, and the rainy season of North China. It has been recognized that the early or late onset of the rainy season and its duration are usually related to the general circulation pattern over the whole of Eurasia. As early as the 1950’s, the significance of the blocking action in the westerlies at 500hPa and the activities of the western North Pacific subtropical high were recognized^[1]. In recent years, further investigation has drawn our attention to the transition of the 100 hPa flow pattern, affirming that the behavior of the South Asia high has great significance in relation to the above-mentioned major weather systems over China in the summer months^[2,3]. Through our investigation of the seasonal variation of the general circulation of the Northern Hemisphere for the period of the QXPMEX in 1979, we have come to realize that the variation of the general circulation pattern over the Northern Hemisphere from the troposphere to the stralosphere and the coupling effect between the lower stratosphere and the upper troposphere must be dealt with before we can turn our attention to the major atmospheric events occurring over Chian in summer.