中文摘要：

基于新的气候标准场（1971-2000年），对ENSO事件的定义及表征特征值作了综合评述。根据海洋尼诺指数ONI，确定了1951-2007年的ENSO事件，计18次暖事件和13次冷事件。通过对1951年以来逐月资料的统计分析，对ENSO的主要指数进行了相关分析，定义了ENSO事件的强度指数，并确定了1997-1998年发生的是自1951年以来最强的暖事件。

英文摘要：

Based on a new sea surface temperature（SST） climatology for the base period 1971 -2000, a review is given for the definition of ENSO events and their indices. According to the oceanic Nifio index （ONI） since 1951, 18 El Nifio events ＇and 13 La Nina events were identified. Finally, ENSO events and their intensities from 1951 through 2007 were classified. Result shows that the El Nino events that occurred in 1997 and early 1998 was the strongest since 1950.