1971—1992年期间埃尔尼诺的发展期特征(英文)  

DEVELOPMENT OF EL NINOS DURING 1971—1992

作　　者：王斌[1] 王炎[1] 

机构地区：[1]夏威夷大学海洋与地球科技学院气象系

出　　处：《海洋湖沼通报》1994年第2期26-40,共15页Transactions of Oceanology and Limnology

摘　　要：小波（wavelet）分析的结果表明埃尔尼诺─南方涛动（ENSO）循环的周期从本世纪五十年代以来经历了显著的变化。其主周期在六十年代中期由六年左右突变为二年左右，随后逐渐增为4年左右。七十年代中期之后，ENSO循环呈现准5年振荡，同时也含有一个明显的准两年振荡分量。最近二十年来，ENSO循环中由冷到暖的状态转换过程有值得注意的相似性。对1971－1992年间的海温、海表气压和风场以及深对流场所做的多变量经验正交函数（MV－EOF）分析指出，最重要的模态描述暖事件的成熟期，第二模态描述暖事件的发展期。ENSO发展期具有以下主要特征；1）在整个热带北太平洋上空有一个准东西向的异常低气压带；2）与此异常低压相适应，在西北热带太平洋出现异常气旋环流，在赤道西太平洋出现异常强西风，在赤道东、中太平洋的越赤道东南信风加强；3）深对流异常区与西太平洋异常西风区几乎重合，它主要是由异常的经向风向赤道的辐合所致。描述发展期的第二模态表现出明显的准两年分量。这与描述成熟期的以5年为主周期的第一模态形成鲜明的对比。The E1 Nino-Southern Oscillation (ENSO) cycle is demonstrated to be highly variable. The dominant frequency changes with time, resulting in a broad band of period ranging from 2 to 7 years. In the mid-1960s the dominant period changed suddenly from 6 years to about 2 years. From the mid-1960s to mid 1970s the period increased gradually from 2 years to 4 years. After the mid-1970s the ENSO cycle has been a quasi 5 year oscillation with a significant quasi-biennial component, and the ENSO events bear considerable similarities in their tiansition from a cold to a warm state.Multi-Yariate empirical orthogonal function (MV-EOF) analysis of the post1970 data indicates that the most significant mode describes the mature phase of ENSO, and the second most significant mode describes an early stage in the ENSO warming. The development of a warm episode is characterized by (a) a planetary-scale low pressure anomaly in the tropical North Pacific, (b) an accompanying quasi-geostrophic cyclonic gyre with relatively strong westerly anomalies in the western equatorial Pacific and enhanced trades in the eastern equatorial Pacific.(c) a conyection anomaly overlapping with the westerly anomaly over the western Pacific due primarily to the meridional wind convergence. This mode displays a significant quasi-biennial component, in contrast to the frist EOF mode which depicts the mature phase of El Nino and exhibits a dominant 5-year period.

关 键 词：厄尔尼诺 海-气关系 太平洋 发展期 

分 类 号：P732.6[天文地球—海洋科学]