热带西太平洋水位的年际变化与ENSO事件

INTERANNUAL VARIATIONS OF SEA LEVEL IN THE WESTERN TROPICAL PACIFIC OCEAN AND ENSO EVENTS

根据美国ＴＯＧＡ水位中心所提供的１９７５—１９８８年水位月平均资料，分析、讨论了热带西太平洋水位的年际变化特征，特别是与ＥＮＳＯ事件有关的低水位现象。此外，还重点叙述了１９８６—１９８７年ＥＮＳＯ事件中水位沿经向和赤道剖面的变化，以及与此有关的赤道流系的变化。文中还定性地讨论了赤道开尔文波沿赤道剖面的传播特性。

Interannual variability of sea level in the western tropical Pacific Ocean are discussed in this paper,on the basis of the monthly mean sea level during the period of 1975 -1988 provided by TOGA SEA LEVEL CENTER. The results of the analysis show that the lowest sea level in the study area is closely associated with ENSO events. Before the events there is a higher sea level in the studied area with a period of 6-12 months (5-14cm higher than normal). Throughout the events there is a maximal fall in the sea level which is 20-30cm lower than normal over a period of about one year.In most of the events, the fall of the sea level is symmetrical around the equator,maximal fall occurs in the vicinity of the Northern Equatorial Countercurrenttrough and Southern Equatorial ridge. By contrast, the fall of the sea level at the equator is smaller.Besides, the paper focuses on the changes in the sea level along the meridional section and equatorial profile during the 1986/1987 event. From the meridional changes,it can be found that the Northern Equatorial Countercurrent (NECC) and Northern Equatorial Current (NEC) become strong during the event, especially the NECC, while the Southern Equatorial Current becomes markedly weak. Changes of the sea level along the equatorial profile is very interesting. Based on the above mentioned changes, the properties in propagation of the Kelvin waves along the equator are also discussed qualitatively.