北半球平流层低层大气季节内振荡特征

CHARACTERISTICS OF INTRASEASONAL OSCILLATION IN LOWER STRATOSPHERE OF NORTHERN HEMISPHERE

利用奇异谱分析方法（ＳＳＡ）分析了１９７５年１月１日至１２月３１日北半球３０ｈＰａ高度场变化特征，结果发现：平流层低层大气除了年变化及季节变化趋势外，还存在明显的季节内振荡，最显著的周期为２０～６０天；在持续性异常多发地区，３０ｈＰａ高度场变化中２０～４０天周期振荡占优势，而在其它一些地区则盛行４０～６０天周期振荡；对流层持续性异常主要同对流层高度场的２０～４０天振荡有关，并可能通过这种周期振荡同平流层低层相同周期的振荡的相互作用影响平流层低层大气季节内变化。

The intraseasonal oscillation features of 30 hPa height field in the Northern Hemisphere from 1 Jan. to 31 Dec. 1975 are investigated by using Singular SpectrumAnalvsis(SSA).The results sbow that there is remarkable intraseasonal oscillation in which the period of 20 to 60 days is predominant in addition to annual variation andseasonal cycle in lower stratosphere. The 20 to 40-day periodic oscillation of the heightvariations at 30 hPa prevails in the frequent occurrence area of persistent anomalies,while 40 to 60 day periodic oscillation in other areas.The persistent anomalies aremainly related to the 20～40 days oscillation in troposphere and likely to affect theintraseasonal variation in lower stratosphere via the interaction between the oscillationsin both troposphere and stratosphere.