ENSO多样性研究进展

El Ni?o是热带中东太平洋异常偏暖的现象，发展过程具有显著的季节锁相特征。近年来，新形态事件更频繁发生引起了科学界广泛关注。学者们根据空间分布形态或爆发时间将ENSO事件分为两类，虽然选取标准不同，分类结果却有诸多相似点:中太平洋(Dateline、Modoki、CP、WP及SU型)El Ni?o事件发展至成熟时，正SSTA中心位于赤道太平洋中部；东太平洋(传统、EP、CT及SP型)El Ni?o发展至成熟时，正SSTA中心位于赤道东太平洋，低层西风异常更强，向东传输的距离也更远。研究结果显示，东太平洋El Ni?o比中太平洋El Ni?o持续时间更长，强度也更强；两类事件对全球气候的影响模态有很大的差异。近几十年，中太平洋El Ni?o出现频率有所增加，但其原因尚未清楚。关于两类事件生成发展和位相转换的动力原因，目前科学界普遍认为东太平洋El Ni?o是一个海盆尺度的海气耦合过程，其生消过程与温跃层的变化有紧密联系，但对中太平洋El Ni?o的动力机制尚未有统一的认识。 

ENSO DIVERSITY: A REVIEW

El Ni?o usually means a significant warming of the ocean surface in the central and eastern tropical Pacific Ocean, and it is phase-locked to the seasonal cycle. In recent years, more occurrences of a new type of ENSO have caused widespread concern. The warm episodes have been classified into two types according to the special structure or the onset time of El Ni?o events. The classifications have a lot of similar characteristics despite the different standards. On the mature phase of the eastern Pacific El Ni?o event, a positive SSTA center is located in the eastern tropical Pacific, surface westerly anomalies are strong and cover a large part of the tropical Pacific. On the mature phase of the central Pacific El Ni?o event, a positive SSTA center confines in the central Pacific. The intensity of the eastern Pacific El Ni?o event is stronger than that of the central Pacific El Ni?o and the duration of the eastern Pacific El Ni?o event is longer than that of the central Pacific El Ni?o. These two types of ENSO events exert quite different influences on the global climate. The frequency of the central Pacific El Ni?o event has increased in recent decades, but the reason for this is not clear yet. As to the mechanisms of the generation, development and phase transition of the two types of ENSO events, a relatively unified understanding of the eastern Pacific El Ni?o is reached. It is generally believed that this type of ENSO appears to be a basin-wide coupling phenomenon between the ocean and the atmosphere and shows a strong teleconnection with thermocline variations. However, the mechanism of central Pacific El Ni?o is quite uncertain.