南海西边界流场的时空变化特征及其与ENSO循环的关系

A study on the temporal and spatial characteristics of the South China Sea western boundary current and its relationship with ENSO cycle

利用SODA同化数据、卫星高度计反演的地转流数据及ICOADS风场资料,刻画了南海西边界流场的三维结构,并着重探讨了中南半岛附近的南海西边界流年际变化特征与ENSO循环的关系.研究结果表明:以经向流速10cm/s界定中南半岛西边界流的核心边界,按此标准其核心区水平方向上为中南半岛沿岸至111°E附近,垂向为200 m以浅.分析发现12.25°N断面西边界流流量的年际变化与ENSO呈显著正相关,流量滞后ENSO 5个月时相关系数最高,达0.38(超过99%置信度).受ENSO期间季风变异影响,和正常年份相比,合成El Nino事件的发展期(7月)-强盛期(12月)-消亡期(次年7月),中南半岛近岸的西边界流呈现增强-减弱-减弱态势;而合成La Nina事件的发展期(7月)-强盛期(12月)-消亡期(次年7月),西边界流却呈现减弱-增强-南强北弱的态势;综上,南海西边界流的年际变化,ENSO是主要调控因素.

With the current data of SODA,geostrophic current data from the satellite altimeter and wind data of ICOADS,we studied on the three-dimensional structural characteristics of the South China Sea western boundary current and probed particularly into the interannual variability of the western boundary current along Indo-China Peninsula and its relationship with ENSO. The results showed that the core boundary of western boundary current along Indo-China Peninsula could be definedas where themeridional velocity was at 10 cm / s,then its range was from Indo-China Peninsula offshore to 111°E horizontally and shallower than 200 m vertically. The variation of the western boundary current volume transport along 12. 25° N section showed noticeable positive correlation with ENSO based on 16 a data. Its maximum correlation value reached 0. 38 when volume data lagged the ENSO index 5 months with a more than 99% confidence interval. Affecting by the monsoon anomaly during the ENSO,synthesis El Nino event,from its expansionstage（ Jul） to strong stage（ Dec）,then to decline stage（ Julat the following year）,the western boundary current along Indo-China Peninsula corresponding showed strengthened to weakened,then to weakened mode. However,at the La Nina event,from its expansion stage（ Jul） to strong stage（ Dec）,then to decline stage（ Julat the following year）,the western boundary current varied from weakened to strengthened,then tostrengthened in south and weakened in north. In total,ENSO was the main control factor on the interannual variability of the South China Sea western boundary current.