西太平洋地区低频振荡特征及其同副高、台风关系的探讨

本文分析了1985年5—9月期间西太平洋地区850hPa上低频振荡的地区分布及其传播,除赤道辐合带活动区域外,西北太平洋副高及澳大利亚高压所在地区也是一个低频波十分活跃的区域。从时间上连续的低频天气图上发现,在低频分量方差大的地区有低频气旋和反气旋在准定常的位置上周期性地循环出现,其传播路径较有规则。它们同副高、台风的活动有较好的关系。北半球的低频振荡向南传播,可以激发南半球的低频波活跃,而南半球的低频波又可以通过影响越赤道气流进而影响台风的活动。

A STUDY ON THE CHARACTERISTICS OF THE LOW-FREQUENCY OSCILLATION OVER WEST PACIFIC AND ITS RELATIONS WITH SUBTROPICAL HIGH AND TYPHOONS

In this paper, by using the daily wind data from May 1 to September 30,1985 at the level of 850hPa, the geographical distribution of the low-frequency oscillation (LFO)(around 40 days) over west Pacific and its propagation features are analysed. The result shows that besides the ITCZ region, there exist other two regions where the 30-50d oscillation dominates. One is over the northwest Pacific Ocean corresponding with the subtropical High, and the other is over Australian continent related to the cold High in Southern winter. From the time-continuous LF weather maps, it is found that the LF cyclones and anticyclones occur alternately in regions of large variance of 30-50d filtered wind, and propagate in rather regular patterns. Also, there exists a good relationship between LF cyclone (anticyclone) and the activity of typhoon (subtropical High).While propagating southward, the LFO in Northern Hemisphere (NH) can trigger the LF wave in Southern Hemisphere (SH),in turn.the LF wave in SH can influence the activity of typhoon in NH by changing the across equatoral flow.