海洋环流与波动重点实验室知识库

黑潮入侵对东海陆架的洋动力和生态环境有着深刻影响。在以往大 多数研究中，黑潮入侵量都是通过 200m等深线的体积输运来评估。然而， 这种近似的替代可能导致黑潮入侵通量低估，因为它无法分离和陆架水的向岸和离输送。
本文建立了覆盖东海、黄渤的三维高分辨率 ROMS（Regional Ocean Modeling System）模式， 并基于此提出了一种全流域被动示踪拟方法暨通过在目标水体研究区域的初始位置释放被动示踪物，完整地记域的 目标水体。示踪物在某一区体积浓度 表示该区域目标水体的积比。 在计算目标水体的积输送时，进一步将该比引入之中。
本文研究表明就气候态的年平均值而言， 向岸的 净黑潮体积输送（ net Kuroshio transport，NKT）高达 1.85Sv（1Sv=106m3 s-1），而离岸的 净陆架水体 净陆架水体 积输送（ net shelf water transport，NST）为-0.42Sv。NKT比 200m等深线 （1.43Sv）的净体积输运量 （net volume transport，NVT）高出 30%左右，表明 黑潮入侵对 ECS的影响可能远大于以往认识。 的影响可能远大于以往认识。
除此之外，本文还讨论了 东海陆架 内区的体积交换问题。动量平衡分析表 明，陆架边缘和内的交换都以地转平衡为主但处更易受非线性影响。敏感试验结果表明，黑潮入侵的变化主要受输送、台湾海峡海流和局地风应力的 共同影响。相比之下，对陆架水离岸输送 有着显著的影响。
对 200m等深线处水交换而言 ：当上游黑潮流量减弱（加强）时，跨200 m等深线的黑潮向岸侵入减弱（加强）；当台湾海峡流量减弱（加强）时，黑潮向岸入侵增强（减弱），陆架水离岸输送减弱（加强）。而局地风对水交换的影响则广泛分布在整个陆架边缘的上层。以夏季风为例，它对陆架水交换的影响是多方面的：一方面，通过增加台湾海峡流为ECS提供更多的陆架水；另一方面，它通过诱导近海Ekman运输来加强陆架水离岸输送。海表热通量对台湾东北部和九州西南部的黑潮入侵有相反的影响：一方面，降温（升温）效应促进（抑制）台湾东北的黑潮向岸入侵和陆架水离岸输送，另一方面，降温（升温）效应能够抑制（促进）九州西南黑潮向岸入侵和陆架水离岸输送。对于100m等深线处的水交换而言，台湾海峡流的强弱对黑潮水交换的影响较大，局地风的影响不容忽视。弱台湾海峡流会加强了黑潮的向内陆架区域的入侵。对于100m等深线的陆架水离岸输送，夏季风和强台湾海峡流都有重要作用。

The Kuroshio intrusion has a profound influence on the marine dynamic and ecological environment in the East China Sea (ECS) shelf. In most previous studies, the intrusion has been evaluated by the volume transport across the 200 m isobath.
A 3-D high-resolution ROMS model covering the ECS, Huang Hai and Bohai Sea is established in this study. Based on this model, a whole-region passive-tracing method is proposed, and the target water body of the study area is completely traced by releasing the passive tracer at the initial position of the target water body in the study area. The concentration of the tracer in a certain area represents the volume ratio of the target water body in that area. When calculating the volume transport of the target water body, the volume ratio of the water body is further introduced into the calculation.
However, this approximate substitution leads to an underestimation of the Kuroshio intruding flux as it fails to separate the onshore and offshore transport of Kuroshio and shelf water. In this paper, a whole-region passive-tracing modeling method is proposed to quantitatively explore the bidirectional exchange of Kuroshio and shelf water, by introducing Kuroshio water concentration as a passive tracer into the flux calculations. In terms of the climatological annual mean, the net Kuroshio transport (NKT) onto the ECS shelf is as high as 1.85 Sv (1 Sv = 106 m3 s−1), with net shelf water transport (NST) of 0.42 Sv. The NKT is about 30% higher than the net volume transport (NVT) across the 200 m isobath (1.43 Sv), which indicates that the influence of the Kuroshio intrusion on the ECS may be far greater than believed before. The volume exchange on the inner shelf of the ECS is also discussed.
Analyses of the momentum balances indicate that the exchanges on both the shelf break and the inner shelf are generally dominated by the geostrophic balance, but the exchange on the shelf break is more susceptible to nonlinear effects. Results of a set of sensitivity experiments show that variation of the Kuroshio intrusion is mainlyregulated by the combined effect of Kuroshio transport, the Taiwan Strait current and local wind stress. In contrast, the local wind stress has a predominant effect on the outflow of shelf water.
For the water exchanges across the 200 m isobath，the Kuroshio and TWS current mainly affect the Kuroshio intrusion northeast Taiwan. By changing the density field, the surface heat flux has an important impact on the Kuroshio intrusion in northeast Taiwan and southwest Kyushu. While the influence of local wind on water exchanges are widely distributed throughout the upper layer of the entire shelf break. The influence of summer monsoon on shelf water exchange is multiple. On one hand, it provides more shelf water for the ECS by increasing the TWS current. On the other hand, it strengthens the shelf water drainage by inducing the offshore Ekman transport. For the water exchanges across the 100 m isobath, the TWS current plays a predominant role, and the influence of local wind cannot be ignored. The weak TWS current greatly promotes the Kuroshio onshore invasion. For shelf water drainage across the 100 m isobath, both the summer monsoon and strong TWS current have an important role.