南极长城站地区气象要素的中期振荡特征

THE MEDIUM-RANGE OSCILLATION OF METEOROLOGICAL ELEMENTS OVER GREAT WALL STATION ON ANTARCTICA

本文用多维谱分析的方法研究了1985年1月-1987年12月南极长城站地面气象要素的谱特征。该地区的气象要素与北半球一样,也普遍存在3-5天、准一周、准二周和3-4周振荡周期。在长城站所在的乔治王岛地区,从地面到平流层中下部,气压系统都存在着显著的准二周振荡,这种振荡是由上往下传播的。无论冬、夏季,准二周和准一周振荡都是由西往东传播的,而扰动的南北传播方向则与季节及振荡周期长度有关。南极地区的中期振荡特征与500hPa极地涡旋的活动和强度变化有密切关系。

A methed of multi-spectral analysis is used to study the spectral characteristics of surface and upperlevel meteorological elements over the Great Wall Station (62°12' S, 58°57' W) on Antarctica and their phasecorrelation, propagation of mean oscillation at 500hPa level in the Southern Hemisphere and their corresponding synoptic sense. the results are summed up as follows: 1.Over the sub-Antatctic zone, as in the Northern Hemisphere there generally exist quasi- weekly oscillation and quasi-biweekly oscillation. In different seasons the oscillations of meteorological elements are different: in winter season quasi-biweekly oscillation is dominant, while in summer season quasi-weekly oscillation is dominant. 2.From the Earth's surface to the lower stratosphere there is a distinct quasi-weekly oscillation at each isobaric surface, but the most intense oscillation appears at 200-300hPa, and the oscillations of height and temperature are propagated downward. 3.Both in winter and summer seasons the quasi-biweekly oscillation are propagated from west to east, and the mean velocity of its propagation is about 7-17 longtitude / day. 4.The quasi-biweekly oscillation and the quasi-weekly oscillation over the sub-Antarctic zone are closely related to the activity and intensity variation of polar vortex at 500hPa, while at 1000hPa they refleet an interaction between the circumpolar depression and the sub-tropical high over Antatctica. The quasi-biweekly oscillation may be a reflection of inherent oscillation of the polar vortex, where as the quasi-weekly oscillation is a reault of forced oscillation by external disturbance. A large number of calculations and analysis made reveals the features of medium-range oscillation over the sub-Antarctic zone. The results are of significance for understanding the behaviour of synoptic dynamics and making the weather forecast. This work is supported by National Committee for Antarctic Research.