夏季上升流影响下琼州海峡温盐结构的天气时间尺度内变化及调控机制

夏季，海南岛东北岸频有沿岸上升流发育（即琼东北上升流），受风场的调制该上升流生消过程具有典型的天气时间尺度；同时，在潮流-地形联合作用以及强潮混合等因素共同影响下，琼东北上升流冷核常出现于琼州海峡东口处。因此，在琼东北上升流事件背景下，海峡东口处涌升的低温、高盐上升流水体很可能在海峡内强烈的准东西向往复潮流的输运下进出海峡，从而在天气时间尺度内对海峡内温盐时空格局产生关键影响。然而，当前人们对夏季上升流影响背景下海峡内温盐结构的天气时间尺度内变化过程及其物理调控机制的认识还较为缺乏。本项目将利用多源数据分析、海洋数值模拟等手段，明确天气时间尺度内琼东北上升流影响下琼州海峡内温盐场的三维结构及时空演变特征，理清风场、潮、地形、混合及背景环流等因子在琼东北上升流生消过程及其水体进出海峡过程中扮演的动力角色，最终揭示夏季上升流影响下琼州海峡温盐结构的天气时间尺度内变化的调控机制。

In summer, upwelling events frequently develop off the northeast coast of Hainan Island. Modulated by the varying winds, the upwelling and relaxation events characterize typical synoptic time scales. Meanwhile, the cold-core of this upwelling is generally located in the east entrance area of the Qiongzhou Strait due to the current-topography interaction and strong tidal mixing. Thus, under upwelling events, the upwelled cold and saline water in the east entrance area of the Qiongzhou Strait will probably pass in and out the strait following the intense tidal currents, thereby remarkably modulating the thermohaline structure of the strait. However, to date, we still have poor knowledge of the variation of the thermohaline structure in the Qiongzhou Strait under the influence of upwelling events and the underlying physical mechanisms remain to be elucidated. Based on multi-source observational and reanalysis data and numerical simulation, this project will explore the three-dimensional structure and spatiotemporal variations of the thermohaline distribution in the Qiongzhou Strait, demonstrate the different dynamical roles of winds, tides, topography, mixing, and background circulation in the upwelling and relaxation events and their contributions to the expansion of the upwelling waters toward the inner strait, and finally clarify the mechanisms dominating the variations of thermohaline in the Qiongzhou Strait under the influence of upwelling.