中文摘要：

基于NOAA OISST．V2月平均SST资料和FSU月平均风应力资料对南海的SST和风场异常进行了分析，发现：南海对1997／1998年El Nin^-o事件响应最为强烈，并在1997／1998年冬季和次年的夏季SST存在2个异常高峰值，风速存在2个异常减小的极值。为研究南海环流在1997／1998年的异常变化，利用ECOM水动力模型计算了1995-2000年的南海环流场，分析了1998年1月和8月南海水位和环流的异常分布，二者均存在显著的异常：①1月，整个南海海盆为正的水位异常，流场为反气旋异常环流，冬季控制整个南海海盆的气旋式环流减弱；②8月，南海海盆水位为正异常，特别是越南东部海区出现较强的正水位异常，南海南部的高水位中心扩大北移；异常流场表现为南部为气旋式异常环流，北部为反气旋的异常环流，且在越南东部海区形成非常强的反气旋异常环流中心，使得控制南海南部的反气旋环流和北部的气旋环流均减弱。风应力的分析表明，风应力旋度的异常变化是南海环流年际异常变化的主要因素。

英文摘要：

Based on the NOAA OISST. V2 monthly SST dataset and FSU monthly windstress, the SST and windstress anomaly distributions in the South China Sea indicated that the South China Sea had been highly affected by the 1997/1998 El Nifio event. The SSTA of February and August in 1998 had two peaks, while the wind speed reached its maximum minus anomalies in January and August. In order to find the circulation anomaly in the South China Sea, the circulation of 1995-2000 had been calculated by the ECOM hydrodynamic numerical model. The elevation and circulation of January and August in 1998 indicated that there were great anomaly of elevation and circulation after this El Nin^o event. （ 1 ） In January, the whole South China Sea had positive sea level anomaly and anti-cyclonic velocity anomaly, so the cyclonic circulation was weaker than normal. （2） In August, the South China Sea had positive sea level anomaly, especially stronger in the east of Vietnam, and cyclonic velocity anomaly in south, anti-cyclonic velocity in north, especially strong in the east of Vietnam. So the cyclonic gyre in the north and the anti-cyclonic gyre in the south were both weaker than normal, and an anti-cyclonic gyre appeared east of Vietnam. The analysis of wind stress curl indicate that the wind stress curl was the main reason for nomaly of elevation and circulation. in the the anomaly of elevation and circulation.