厄尔尼诺/拉尼娜信号循环回路及其传播特性研究

On the circuit and propagation of El Nio/La Nia signals

基于1992～2001年卫星高度计资料分析了海面高度距平在厄尔尼诺/拉尼娜(ElNi o/LaNi a)现象中的演变过程,发现:(1)在ElNi o过程中,海面高度正距平信号从西太平洋沿赤道海域向东传播至东海岸,然后分成南北两支,北支在10°N附近从东太平洋传回西太平洋的信号最强,到达西太沿岸海域再传回赤道,表明ElNi o信号传播在北半球存在一明显循环回路.赤道以南循环圈不及赤道以北环路清晰.东太平洋的季节变化信号主要通过6°N,10°N和8°S附近的3个通道向西太平洋传播.LaNi a信号主要从5°N和7°S向西传播;(2)在大洋海盆尺度快速传播信号背景下,存在波长700～800km的慢速传播信号,两类信号将信息在太平洋内传送.传播速度分析表明,慢速传播信号的相速与Rossby波相速相符,而快速传播信号应该是海洋对大气变异的响应.

Based on the T/P altimeter dataset between October 1992 and December 2000, the circuit of El Nio/La Nia signals are studied. (1) In El Nio cases, positive sea level anomaly (SLA) signals propagate eastward from equatorial west to east in the Pacific. After reaching the coastal area, the signals go to polar directions along the eastern boundary and continuously generate westward propagating Rossby waves. In the period of El Nio, the fact that the signal of the Rossby waves is the strongest near 10°N suggests that an signal circuit bounded by the equator and 10°N exists. The other El Nio signal circuit bounded by the equator and 10°S also exists, however relatively weak compared with its northern counterpart. Westward La Nia signals mainly are located in the channels centered 5°N and 7°S respectively. Westward seasonal signals mainly are located in the three channels centered at 6°N,10°N and 8°S respectively. (2) Two kinds of signals, fast and slow, transport El Nio information from East to West Pacific at the same latitude. The phase speed of the slow one with wavelength of 700～800 km is consistent with that of Rossby wave. The basin scale signals propagate so fast that it should be the oceanic response to atmospheric anomaly.