南海在1997/1998年El Niño事件后的异常变化

Abstract

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 Nio 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 Ni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 in the east of Vietnam.The analysis of wind stress curl indicate that the wind stress curl was the main reason for the anomaly of elevation and circulation.