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首页> 外文学位 >Tidal Dynamics in the South China Sea and Estuarine & Adjacent Shelf Circulation in the Pearl River Estuary: Modeling Studies.
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Tidal Dynamics in the South China Sea and Estuarine & Adjacent Shelf Circulation in the Pearl River Estuary: Modeling Studies.

机译：南中国海的潮汐动力学以及珠江口的河口和邻近大陆架环流：模拟研究。

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摘要

Numerical studies of the tides in the South China Sea (SCS) and circulations in the Pearl River Estuary (PRE) and adjacent shelf are carried out by developing a numerical modeling system that includes a tidal circulation model in the SCS basin, a conceptual and a realistic three-dimensional coupled estuary-shelf circulation models forced by wind stress, tides, and river discharge around the PRE. The high resolution tidal model utilizes a physically sensible domain and assimilates Topex/Poseidon (T/P) data through an efficient generalized inverse scheme. The coupled estuary-shelf modeling is a physically novel study that investigates the interactive roles of the wind, tide and buoyancy forcing and dynamic processes of buoyant plume, estuarine circulation and shelf circulations in the PRE region.;Tidal simulation in the SCS well simulates the observed feature and provides tidal forcing for the subsequent coupled estuarine-shelf circulation models around the PRE, and investigates the dynamics and energy of tides in a semi-enclosed sea. The study, for the first time, reveals the amplified K1 tide in the SCS basin as a result of the Helmholtz resonance. Analysis of tidal energy shows that the energy dissipates mostly in the LS and strong dissipation of M2 tide also occurs in the Taiwan Strait (TS). The work rate of the tidal generating force in the SCS basin is negative for M2 and positive for K1. The different responses of the M2 and K 1 tides in the SCS are largely controlled by the intruding directions of the tides from the Pacific, the tidal frequency, the wavelengths, the local geometry and the bottom topography.;A conceptual coupled estuary-shelf model that utilizes representative, but idealized forcing and topography is developed to better identify the fundamental but extremely complex physical processes in a simple but physically well-defined system. Results show that a buoyancy-driven anti-cyclonic eddy is developed inside the idealized PRE under both the gravitational and Coriolis effects, but dissolved by additional tide or wind forcing. The shape and spreading speed of the Pearl River plume are greatly modified by the wind and tidal forcing, in which, the thickness of the plume is increased and the propagation speed is retarded by strong tidal mixing in the estuary, while the plume is narrowed and accelerated by the wind-driven coastal currents over the shelf . The upwelling/downwelling coastal jet intrudes into the estuary with different current patterns and these shelf processes largely influence the estuarine circulation.;Forced by observed time-dependent wind, buoyancy, and tidal forcing, the direct simulation in the coupled estuarine-shelf model in the PRE adopts high spatial resolution that better resolves the realistic topography and coastal geometry. With the implementations of suitable numerical schemes and physically sensible open boundary conditions, circulation and related dynamics resulting from the interactions between the topography and multi-forcing processes are explored. It is found that the patterns of the coastal upwelling currents are largely controlled by the topography and greatly modified by the tide and buoyancy forcing over the shelf, and the coastal bays and estuaries with wide entrance are favorable for the intrusion of the upwelling coastal jets. Tidal residual currents and tide-induced redistribution of the sea surface pressure gradient field strengthen/weaken the coastal upwelling jet and bottom onshore currents on the eastern/western shelf. The buoyant plume enhances the eastward and southward motion of the surface upwelling currents as a result of thinned surface Ekman layer and formation of pressure gradient between the plume and ambient sea water. Inside the PRE, the circulation has little response to the wind forcing in the upper part, but is largely influenced by the intrusion of the time-dependent coastal circulation. Analysis of the plume and current features in spring-neap cycle reveals that the variable competition of the tide and buoyancy forcing determines the circulation around the entrance of the PRE.
机译：通过开发一个包括南海盆地的潮汐环流模型，一个概念性的和一个区域性的数值模拟系统，对南中国海的潮汐和珠江口（PRE）及邻近陆架的环流进行了数值研究。在PRE周围的风应力，潮汐和河流排泄作用下逼真的三维耦合河口-陆架耦合模型。高分辨率潮汐模型利用物理敏感域，并通过有效的广义逆方案吸收Topex / Poseidon（T / P）数据。河口-陆架耦合模型是一项物理新颖的研究，研究了PRE地区的风，潮汐和浮力强迫以及浮羽，河口环流和架子环流的动力学过程的相互作用。观测的特征，并为随后的PRE附近的河口-陆架耦合模式提供了潮汐强迫，并研究了半封闭海域的潮汐动力和能量。这项研究首次揭示了亥姆霍兹共振导致SCS盆地中K1潮汐放大。潮汐能分析表明，该能量大部分耗散在LS内，M2潮汐也大量耗散在台湾海峡（TS）。 SCS盆地中的潮汐产生力的工作速率对M2为负，对K1为正。南海潮汐中M2和K 1潮汐的不同响应很大程度上受太平洋潮汐的侵入方向，潮汐频率，波长，局部几何形状和底部地形的影响。利用具有代表性但理想化的强迫和地形的方法，可以更好地识别简单但定义明确的系统中的基本但极其复杂的物理过程。结果表明，在重力和科里奥利效应的共同作用下，理想化的PRE内部产生了由浮力驱动的反气旋涡，但由于额外的潮汐或强风作用而使其溶解。珠江羽流的形状和传播速度被风和潮汐强迫极大地改变，其中，由于河口强烈的潮气混合，羽流的厚度增加了，而传播速度受到了阻碍，而羽流变窄了。架子上的沿海风流加速上升/下降沿岸的喷气流以不同的电流模式侵入河口，这些陆架过程对河口的环流有很大影响。 PRE采用高空间分辨率，可以更好地解析实际地形和沿海几何。通过适当的数值方案和对物理敏感的开放边界条件的实现，探索了由地形和多受力过程之间的相互作用导致的环流和相关动力学。研究发现，沿海上升流的形式主要受地形控制，而潮汐和浮力作用大大改变了沿海上升流，沿海海湾和入海口较宽的河口有利于上升流喷射。潮汐剩余流和潮汐引起的海面压力梯度场的重新分布会增强/减弱东部/西部陆架上的沿海上升流和底部陆上洋流。由于表面埃克曼层变薄以及在羽流与周围海水之间形成压力梯度，浮羽增强了表面上升流的向东和向南运动。在PRE内，环流对上部的强风响应不大，但受时间依赖性沿海环流的侵入影响很大。对春季-午睡周期中羽流和当前特征的分析表明，潮汐和浮力强迫的可变竞争决定了PRE入口周围的循环。

著录项

  • 作者

    Zu, Tingting.;

  • 作者单位

    Hong Kong University of Science and Technology (Hong Kong).;

  • 授予单位 Hong Kong University of Science and Technology (Hong Kong).;
  • 学科 Physical Oceanography.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 161 p.
  • 总页数 161
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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