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Numerical model investigations of wind-driven coastal circulation.

机译:风力驱动的沿海环流的数值模型研究。

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摘要

The effects of wind forcing on coastal ocean circulation are studied using a numerical modeling approach. The first region of interest is on the North Carolina shelf, where the Coastal Ocean Processes (CoOP) Inner Shelf Study (ISS) took place during August--November 1994. ISS observations are used to initialize, force, and compare results from a two-dimensional version (variations across-shore and with depth; uniformity alongshore) of the primitive equation Princeton Ocean Model. Both strongly stratified and weakly stratified conditions, found during August and October, respectively, are studied. An additional difference between these two periods is that August is characterized by fluctuating alongshelf winds, while October is dominated by downwelling-favorable winds. Momentum term balances, across-shelf transport values, and Lagrangian dynamics are contrasted for the August and October periods. The nonlinear advection terms contribute significantly to the alongshelf momentum balance in depths less than 10 m during upwelling, but not during downwelling.; This result regarding the asymmetry in the shelf response during upwelling and downwelling motivates further study in this region using the same model setup with forcing by periodic alongshelf wind stress. This periodicity allows further investigation of the upwelling-downwelling asymmetries and the Lagrangian characteristics of the flow. An important result of the asymmetric upwelling and downwelling responses is a non-zero mean Eulerian and Lagrangian velocity over the forcing period. These mean velocities differ, leading to a mean Stokes velocity that is largest in the complex region near the coast where parcel trajectories are irregular. A Lagrangian mapping technique and calculation of the largest Lyapunov exponent help identify the nature of fluid parcel displacements over many periods.; Focus of the modeling effort then shifts to the region of the northern California shelf, where the CoOP Wind Events and Shelf Transport (WEST) program collected measurements during January 2000--May 2003. The three-dimensional Regional Ocean Modeling System (ROMS) primitive equation model is initialized and forced with WEST observations, and extensive model-data comparisons are made with three WEST datasets. The model compares reasonably well with moored velocity measurements, CODAR surface current observations, and shipboard hydrographic measurements. The mean response over the summer period is dominated by an upwelling circulation, including a coastal jet that separates off Pt. Arena and Pt. Reyes. Flow near Pt. Reyes during an upwelling and relaxation wind event is complicated and the response north and south of the cape is quite different. Lagrangian results reveal that the source of upwelled water near the coast south of Pt. Reyes is local, as compared to that north of Pt. Reyes, which has a signature of deeper water from farther north. Momentum term balances help to clarify the event dynamics as a function of shelf location. The Lagrangian analyses include both a parcel tracking and label advection technique and provide detailed information on the upwelling response of fluid parcels on the shelf.
机译:使用数值模拟方法研究了强迫对沿海海洋环流的影响。第一个感兴趣的区域是北卡罗来纳州的架子,1994年8月至11月进行了沿海海洋过程(CoOP)内架研究(ISS)。ISS观测用于初始化,强迫和比较两个观测的结果等式普林斯顿海洋模型的三维版本(跨岸且随深度变化;沿岸均匀)。研究分别在八月和十月发现的强分层和弱分层条件。这两个时期之间的另一个区别是,8月的特征是沿陆架风的波动,而10月的特征是沿井下有利的风。 8月和10月期间的动量项余额,跨架运输价值和拉格朗日动力学进行了对比。非线性对流项在上升过程中对深度小于10 m的沿架动量平衡有很大贡献,而在下降过程中则没有。关于上升和下降过程中架子响应的不对称性的这一结果,促使该地区使用相同的模型设置并通过周期性的沿架风应力强迫对该区域进行进一步研究。该周期性允许进一步研究流的上升-下降下降不对称性和拉格朗日特性。上升和下降反应不对称的一个重要结果是在强迫期间平均欧拉速度和拉格朗日速度非零。这些平均速度各不相同,导致平均斯托克斯速度在海岸轨迹不规则的复杂区域内最大。拉格朗日制图技术和最大Lyapunov指数的计算有助于确定许多时期内流体包裹位移的性质。然后,建模工作的重点转移到加利福尼亚北部的架子地区,CoOP风能活动和货架运输(WEST)程序在2000年1月至2003年5月期间收集了测量值。三维区域海洋建模系统(ROMS)原语用WEST观测值对方程模型进行初始化和强制,并使用三个WEST数据集进行了广泛的模型数据比较。该模型与系泊速度测量值,CODAR表面电流观测值和船上水文测量值比较合理。夏季期间的平均响应主要由上升流环流控制,包括将Pt分隔开的沿海喷流。竞技场和铂雷耶斯铂附近的流量。雷耶斯在上涌和松弛风事件中非常复杂,海角南北的反应也大不相同。拉格朗日的结果表明,Pt以南海岸附近的上升水源。与Pt以北的雷耶斯相比,雷耶斯是地方性的。雷耶斯(Reyes)具有更北端较深水域的特征。动量术语平衡有助于阐明事件动态与货架位置的关系。拉格朗日分析包括包裹跟踪和标签平流技术,并提供有关架子上流体包裹上升响应的详细信息。

著录项

  • 作者

    Cervantes, Brandy T.;

  • 作者单位

    Oregon State University.;

  • 授予单位 Oregon State University.;
  • 学科 Physical Oceanography.
  • 学位 Ph.D.
  • 年度 2005
  • 页码 159 p.
  • 总页数 159
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 海洋物理学;
  • 关键词

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