Modeling South China sea circulation: Response to seasonal forcing regimes
Modeling South China sea circulation: Response to seasonal forcing regimes
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DOI：
10.1029/2005jc003298
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发表时间：
2006-06-24
影响因子：
3.6
通讯作者：
Haidvogel, D. B.
中科院分区：
文献类型：
--
作者：
Gan, Jianping;Li, H.;Haidvogel, D. B.
利用三维海洋模式研究了亚洲季风和黑潮入侵对南海环流及其季节变化的影响。南海海洋模式的分辨率约为10公里的水平间距和30个垂直水平与现实的海底地形。该模式被迫与时间相关的风应力和热通量从国家环境预报再分析中心的数据，以及与横向通量从太平洋模式的水平分辨率为40公里。本研究分析了季风风应力、黑潮入侵及其他内在强迫过程对平均季节环流及动力过程的影响。结果表明，南海的季节环流主要受季风风应力驱动，黑潮入侵对南海的季节环流有很大影响。冬季和夏季，沿南海大陆边缘的强海流沿着形成平均的海盆气旋和反气旋环流。多尺度涡旋嵌入在整个流域的大气环流。当黑潮主流通过吕宋海峡而不侵入南海时，当冬季动力条件在南海北部占优势时，部分入侵发生在台湾西南陆架边缘附近的200 m上部。黑潮对南海的入侵也是四季都有，主要是沿着大陆坡。越南南部以东的沿岸流分离和相关的涡旋形成是南海南部环流的特征。模拟结果与相应的观测结果吻合较好。动力学过程中所涉及的强制流场的动量平衡的检查进行了研究。分析表明，南海环流总体上受地转流控制。在吕宋海峡以北，纬向正非线性局部增强，导致黑潮主流向东转向形成向心加速度。黑潮的侵入受非地转流的控制，并与净向西向压力梯度力密切相关。越南以东的海岸急流分离主要与当地的风应力场和陆架地形在夏季和冬季，分别。敏感性研究表明，黑潮的减弱显著增强了黑潮的入侵，并在吕宋海峡以西形成一个反气旋式涡旋。
A three-dimensional ocean model has been utilized to study circulation and its seasonal variation in the South China Sea (SCS) in response to the forcing of the Asian monsoon and the Kuroshio intrusion. The SCS ocean model has a resolution of approximately 10 km horizontal spacing and 30 vertical levels with a realistic bottom topography. The model is forced with time-dependent wind stress and heat flux from National Center for Environmental Prediction Reanalysis data as well as with lateral fluxes from a Pacific Ocean model of 40 km horizontal resolution. This study reports on the analysis of the mean seasonal circulation and dynamic processes in response to monsoonal wind stress, the Kuroshio intrusion, and other intrinsic forcing processes. It is found that the seasonal circulation in the SCS is mainly driven by the monsoonal wind stress and greatly influenced by the inflow from the Kuroshio intrusion. Strong currents along the continental margin of the SCS form mean basin-wide cyclonic and anticyclonic circulations in the winter and summer, respectively. Multiscale eddies are embedded in the general circulation across the basin. While mainstream of the Kuroshio passes through the Luzon Strait without intruding into the SCS, partial intrusion occurs in the upper 200 m near the shelf margin southwest of Taiwan at times when winter dynamic conditions prevail in the north SCS. The intrusion of the Kuroshio into the SCS also occurs at depths in all seasons, mainly along the continental slope. The coastal current separation to the east off southern Vietnam and the associated eddy formations characterize the circulation in the south SCS. The simulated results compare well with the corresponding observed fields. Dynamical processes involved in the forced flow fields are investigated by examination of the momentum balances. The analyses reveal that the circulation in the SCS is generally dominated by the geostrophic currents. North of the Luzon Strait, positive nonlinearity in the zonal direction is locally intensified, which leads to the formation of centripetal acceleration for the mainstream of the Kuroshio to turn eastward. The Kuroshio intrusion at depths is governed by the ageostrophic flows and highly associated with the net westward pressure gradient force. Coastal jet separation to the east off Vietnam is mainly associated with the local wind stress field and with the shelf topography in the summer and winter, respectively. Sensitivity study reveals that the weakening of the Kuroshio markedly enhances Kuroshio's intrusion and forms an anticyclonic eddy west of the Luzon Strait.