基于水动力ROMS与BOX耦合模型的长江口及邻近水域水通量及水体交换特性

WATER FLUX AND EXCHANGE IN CHANGJIANG RIVER ESTUARY AND ADJACENT WATERS ON COUPLED MODEL OF HYDRODYNAMIC ROMS AND BOX MODEL

本研究将水动力模型ROMS(regional oceanic modeling system,区域海洋模式系统)与箱式(box)模型结合,详细阐述了长江口及邻近水域四个季节的水通量特征及水体交换特性。研究发现:总的水通量整体受季风控制,季风的作用在于使水体在南北方向上交替输送,而台湾暖流对春夏季底层水南向输运具有重要作用;直接进入123.5°E以东外海区域的水通量很小,而是先从南边界流出研究区域,然后通过海洋环流系统进入外海。在强烈季风下,水体更新依赖于季风方向的水平通量,主要是同层水体而不是表底层水体之间的交换。虽然水体更新时间较长的区域与缺氧区基本一致,但本研究认为该区域底层水体缺氧的本质原因是跃层阻隔了表底层水体之间的交换。

To understand the water flux and water exchange in Changjiang(Yangtze) River estuary in detail, we combined the hydrodynamic model ROMS(regional oceanic modeling system) and the box model. Results show that monsoon controlled the water flux as a whole and transport water in north-south direction. The Taiwan Warm currents played an important role in moving lower waters in spring and summer. The Changjiang River discharge was not mixed with the open seas directly east of 123.5°E, but transported out of the study area across the southern boundary and then to the open seas by ocean current system. Under a strong monsoon, water exchange depended more on the horizontal water flux in the direction of the monsoon in the same layer but between upper and lower layers. Although longer water exchange time coincided with an anoxia event, the decisive cause of anoxia was the spring layer that hindered the exchange between the upper and lower waters.