1982—1983年冬季亚澳地区低频振荡的分布与联系

DISTRIBUTION OF THE LOW-FREQUENCY OSCILLATIONS OVER THE ASIAN-AUSTRALIAN AREA BURING THE WINTER OF 1982-1983 AND THEIR RELATIONS

本文根据1982年11月16日-1983年3月15日欧洲中期预报中心的网点资料,用低频带通滤波和最大熵谱方法,分析了准40天低频振荡在亚澳地区的分布特征以及这个地区不同地域的低频变化间的联系。发现北半球中纬度的锋区及东亚西风急流的活动均有明显的准40天低频振荡特征;对应西太平洋副高的东西摆动也有准40天规律。而副高的移动造成低层其南侧偏北风越赤道气流在110-180°E范围内的强弱变化,从而对澳大利亚季风的活跃与中断产生重要影响。因此,北半球中纬度斜压性的低频活动与南半球澳大利亚夏季风过程有密切关系。

On the basis of the ECMWE grid data from November 16. 1982 to March 15,1983,the distribution of quasi-40-day low-frequency oscillations over East Asia andAustralia and the relation between the oscillations in different districts of the said areaare investigated by means of low-frequency filtering and the maximum entropy spectralanalysis. Results suggest that the behaviors of the NH mid-latitude frontal zone andthe East Asian westerly jet exhibit obvious characteristics of quasi-40-day periodic os-cillations and the same is true for the corresponding east-west movement of the westPacific subtropical high in the NH. The moving of the subtropical high causes fluctua-tions in intensity of the low-level cross-equatorial air flows of the northeast trade onthe south side of the high in the 110-180°E area, thus exerting an important impact onthe activity and interruption of the Australian monsoon. Thus, the baroclinic low-fre-quency oscillations in the NH mid-latitude are closely related to the Australian summermonsoon.