两类E1　Nino事件太平洋海温异常时空结构的分析

THE TEMPORAL AND SPATIAL STRUCTURE ANALYSES OF PACIFIC SSTA ACCOMPANYING WITH TWO KINDS OF EL NINO EVENTS

用聚类法对１９５１─１９８６年发生的１０次厄尔尼诺事件进行分析，归纳出两类厄尔尼诺事件。第Ⅰ类在赤道中太平洋偏西先开始增温，第Ⅱ类在赤道东太平洋先开始增温；用距平合成和复自然正交经验展开研究了两类事件从产生到消亡各阶段所对应的太平洋海温异常的时空结构和特征。爆发和发展阶段，第Ⅰ类海温场扰动由西向东传，第Ⅱ类相反。距平分布也呈明显相反的特征。成熟阶段，赤道地区第Ⅰ类逆转为由东向西传播；第Ⅱ类则出现经向北传、纬向准静止；中高纬地区两类仍相反，而距平分布的相反特征则已经消失。消亡阶段，海温场的扰动传播第Ⅱ类与成熟阶段变化不大，而第Ⅰ类就变成与第Ⅱ类一致；距平分布也差别不大。

Ten E1 Nino events for 1951-1986 are analysed through the method of clustering and 2 categories are derived. Category 1 (C1) begins heating west of the equatorial eastern Pacific while Category 2 (C2) right over the equatorial eastern Pacific. The two categories of events are studied by means of anomaly compositing and dual expression of EOF in terms of the temporal and spatial structure and characteristics of the anomalous SSTA in the Pacific accompanying with stages from generation to disintegration. At the stages of generation and development, the disturbance in SST field propagates towards east for C1 and `west for C2. Significant opposite features also exist in the anomalous distribution. At the maturing stage, the propagation reverses to the west in the equatorial area for C1 but changes to the north along the longitude and comes to quasi-stationary state for C2. Opposite features still exist in mid-latitudes but those for anomaly distribution disappear. At the disintegration stage, the propagation of disturbed SST fields does not vary much from the previous stage for C2 while C1 becomes consistent with C2 in this respect and does not differ much from C2 in the asnomaly distribution.