1983与1985年夏季北半球500hPa高度场大气低频波的振荡特征

Low Frequency Oscillation Characteristics of Summer of 1983 and 1985

本文利用观测资料分析了１９８３与１９８５年夏季半球５００ｈＰａ高度场大气低频波的振荡特征。结果表明，１９８３年（厄尔尼诺年）夏季热带中、东太平洋和印度洋以及东亚季风区上空的低频振荡比１９８５年（反厄尔尼诺年）夏季的低频振荡强，而热带西太平洋的情况恰好相反。这是由于反厄尔尼诺年夏季热带西太平洋对流活动强盛所致。分析结果还表明：１９８３年夏季低频波基本上是东传的；１９８５年夏季，在中高纬度地区低频波主要还是东传，热带是西传。西藏高原是大气低频振荡的汇区。

In this paper, observational data are used to compare the characteristics of atmospheric low frequency oscillations in the summers of 1983 and 1985. It is indicated that in general the low frequency oscillation in 1983 is stronger than that in 1985 over the central and eastern tropical Padfic, the Indian Ocean and the East Asian monsoon region, but the condition over the western tropical Pacific is contrary to that of the former areas, which is caused by intense convective activities over the western tropical Pacific in the summer of 1985. In addition, the results show that the summer low frequency oscillations in 1983 propagate eastward on the whole, while those at the middle and high latitudes mainly move eastWard in the summer of '1985, but there are westward propagation in the tropics. The Tibetan Plateau is a sink region of the atmospheric low frequency oscillation.