春季热带地区OLR低频振荡及其与长江中下游连阴雨

本文应用NOAA卫星接收的1975—1983年向外长波辐射(OLR)资料研究了春季热带地区低频振荡的基本特征,得出东半球热带地区盛行周期为30天左右的低频振荡,这种振荡最显著的区域在0—10°S、70—90°E的印度洋地区。文章阐述了过渡季节这种低频振荡的经向和纬向传播特征。 本文还进一步指出,在热带低频振荡的不同阶段,ITCZ、北半球副热带以及西风带环流系统也呈现出显著的周期变化,并查证了低频振荡作为长江中下游连阴雨和连晴过程的背景事实。因此本研究工作也为长江中下游连阴雨和连晴天气的中、长期可预报性提供

Low frequency oscillation of OLR over tropics during spring and its relationship with persistent rainy period in middle and lower reaches of Yangtze River

In this paper Outgoing Longwave Radiation (OLR) data of NOAA are used to investigate the essential characteristics of low. frequency oscillation over tropics during spring. It is obtained that 30-day low frequency oscillation prevails over the tropics of the Eastern Hemisphere. The characteristics of meridional and zonal propagations of the oscillation during transition season are also discussed. Furthermore, in different stages of this low frequency significant periodic variations of ITCZ and the circulation systems of the subtropics and westerly belt over the Northern Hemisphere are found. After verifying, such a conclusion can be reached that low frequency oscillation may be regarded as the background condition of the appearances and the developments of persistent rainy period and sunny period in the middle and lower reaches of the Yangtze River.