Primary Study of the South China Sea Circulation Inter-annual Variation

On the South China Sea the NOAA OISST.V2 average SST field and FSU monthly average wind stress field and its anomalous field: South China Sea SSTA and ENSO index has a significant correlation between the SSTA lag ENSO Index 5 months, the relevant the largest coefficient of 0.36, which indicates that the South China Sea obvious response to ENSO and ENSO events, five months after the outbreak of the most significant response; South China Sea, most strongly in response to the 1997/98 El Nino event, the 1997/98 winter and next summer there are two abnormal peak, there are two exceptions to reduce extremes of wind speed. ECOM hydrodynamic model to study the circulation of the South China Sea in the 1997/98 El Nino event occurs, driven by the FSU monthly mean wind stress and first NOAA OISST.V2 months average SST field and open boundary flow to simulate the 1995-2000 SCS circulation Course. The analysis shows that the 1995-2000 average water level courses and circulation fields: the circulation of the South China Sea there are significant seasonal variation, the winter is a basin-scale cyclonic circulation control; a strong anticyclonic circulation in the southern summer, the northern cyclonic circulation control. In this average level field and circulation fields on the basis of the analysis of the January 1998 and August water levels and abnormal distribution of the flow field in the South China Sea, both of which there is a significant exception: (1) in January, the entire South China Sea basin abnormal water level, flow field as anti-cyclone abnormal circulation, winter cyclonic circulation control of the entire South China Sea basin weakened; (2) in August, the South China Sea basin water level is abnormal, especially in the eastern sea area of ??Vietnam a strong positive water level exception, making the high water mark of the southern South China Sea Center to expand northward; the abnormal flow field performance of southern cyclonic anomaly circulation, abnormal circulation of the northern anticyclone formed a very strong anti-cyclonic anomaly circulation center, and in the eastern sea area of ??Vietnam, so that the control of the southern South China Sea anticyclonic circulation and northern cyclonic circulation weakened, and Vietnam eastern anticyclonic circulation flow anomalies performance of the sea anticyclonic circulation. EOF decomposition model results of six years from 1995 to 2000, the time coefficient of water level and flow field distribution showed that there is a significant exception of the South China Sea circulation in 1997-1998; their time variation of the space-state analysis of the South China Sea in 1997 / strong El Nino event occurred in 1998, there was a significant abnormal changes: (1) The 1997/98 winter from November to March, the first modal coefficient significantly reduced cyclonic circulation significantly reduced; (2) 1998 summer from July to October, the second mode coefficient decreases significantly weakened anticyclonic circulation in the southern South China Sea and northern cyclonic circulation. Wind stress analysis showed that the wind stress curl abnormal changes in the South China Sea circulation interannual changes in the main factors.