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Developing an Unstructured Grid, Coupled Storm Surge, Wind Wave and Inundation Model for Super-regional Applications.

机译：为超区域应用程序开发非结构化网格，风暴潮，风浪和淹没模型。

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摘要

During extreme weather conditions such as hurricanes and nor'easters, both the currents and wind waves generated by the atmospheric forces are important. Although they may act and dominate on different temporal and spatial scales, their interactions and combined effects are without doubt significant. In this dissertation, a major effort has been made to couple an unstructured grid circulation model SELFE (semi-implicit, Eulerian-Lagrangian finite element model) and the WWM II (Wind Wave model II). Moreover, this new coupled model system can be executed in a parallel computational environment. After the coupled model was successfully built, the model was verified with ideal test cases, either through comparisons with analytic solutions or with laboratory experiments. It was further validated by field-measured data during two hurricane events.;The SELFE-WWM II model framework described above was used to participate in a SURA testbed project that was recently funded by the NOAA IOOS program. The purpose was to improve the storm surge and inundation modeling skill throughout the Gulf of Mexico as well as along the U.S. East Coast. The coupled tide, surge, and wind wave models in two and three dimensions were tested and compared systematically. Two well-known cases were investigated in detail. One was the event of Hurricane Ike of 2008 in the Gulf of Mexico and the other was the April Nor'easter of 2007 in the Gulf of Maine.;For the Gulf of Mexico study, the key scientific issue is the origin of the forerunner. It has long been recognized that the forerunner plays an important role in generating large hurricane-induced storm surge in the Gulf of Mexico. The forerunner is a phenomenon whereby water level throughout the vast coastal region was elevated days before the hurricane makes landfall. The forerunner can contribute significantly to the total water level that results subsequently during the primary surge when the hurricane makes landfall. The 2008 Hurricane Ike, which devastated the Galveston Bay along the Texas Coast, is a good example: 1.4 m out of 4.5 m maximum surge was contributed by the forerunner in the Gulf of Mexico. The consensus from initial results of multiple models indicates that the forerunner occurred as a result of Ekman set-up along the broad Louisiana-Texas (LATEX) shelf by the shore-parallel wind field. By contrast, the primary surge was dominated by the low pressure and the maximum wind along a path perpendicular to the shore as the hurricane made landfall. It was found that the cross-shore Ekman set-up is highly sensitive to the bottom boundary layer (BBL) dynamics, especially to the drag coefficient. Given the fact that the Gulf of Mexico is known to be rich in fluid mud, and near-bed flows generally are very weak under fair-weather conditions, one plausible hypothesis is that, during the stormy condition, the suspended sediment-induced density stratification is likely to be ubiquitously present at the bottom boundary layer. A sediment-transport model and wave-current bottom boundary layer sub-model including the sediment-induced stratification effect were coupled to the unstructured grid circulation and wind wave model (SELFE-WWM II) for simulating the forerunner during Hurricane Ike. The model results demonstrate that the bottom boundary layer dynamics have a significant effect on the velocity veering as well as the Ekman set-up across the shelf.;In the Gulf of Maine study, the high-resolution coupled SELFE-WWM II model was applied in the Scituate Harbor, a small, shallow coastal embayment, south of Boston. The key issue for the study was the recurring inundation related to the role played by wind waves during nor'easter events. With limited observation data in the Scituate, the model result from SELFE was compared with that from FVCOM. The major findings are summarized as follows: (1) wind waves generated by the nor'easter can profoundly affect the coastal current by increasing the magnitude and altering its direction, (2) while the mean water level inside the Harbor stays the same, the total transport across the harbor mouth increases when wind waves are included, and (3) the total inundation area, primarily in the northern and southern basins within the Harbor, does increase when wind waves are included. There is a question as to why the inclusion of the wind waves did not cause the mean water level to change inside the Harbor while the inundation area was increased. The plausible explanation is that this lack of impact could be that the Stokes transport was small and the increase of water level by the wave set-up was compensated by the expansion of the inundation area in the shallow region.
机译：在极端天气条件下，例如飓风和东风，大气压力产生的气流和风浪都很重要。尽管它们可能在不同的时空尺度上发挥作用和发挥作用，但它们的相互作用和综合作用无疑是重要的。本文主要研究了非结构化网格环流模型SELFE（半隐式，欧拉-拉格朗日有限元模型）和WWM II（风波模型II）的耦合。而且，这种新的耦合模型系统可以在并行计算环境中执行。成功建立耦合模型后，可以通过与分析解决方案进行比较或与实验室实验进行比较，以理想的测试案例对模型进行验证。在两次飓风事件期间，通过现场测量的数据进一步验证了该方法。上述SELFE-WWM II模型框架用于参与最近由NOAA IOOS计划资助的SURA测试平台项目。目的是提高整个墨西哥湾以及美国东海岸的风暴潮和淹没建模技能。对二维和三维的潮汐，潮汐和风浪耦合模型进行了测试和系统比较。详细调查了两个著名案例。一个是在墨西哥湾发生的2008年艾克飓风事件，另一个是在缅因州海湾发生的2007年4月Nor'easter事件；对于墨西哥湾研究而言，关键的科学问题是先驱者的起源。长期以来，人们已经认识到，先行者在墨西哥湾引发飓风引发的风暴潮中起着重要作用。前兆是一种现象，飓风登陆前几天，整个沿海地区的水位都升高了。飓风登陆之前，先行者可以对随后的初次浪涌中的总水位做出重要贡献。一个很好的例子是2008年的艾克飓风对德克萨斯州沿岸的加尔维斯顿湾造成了破坏：在最大涌浪中，有1.4 m来自墨西哥湾的先驱。多个模型的初始结果的共识表明，先驱者是由于沿岸平行风场沿路易斯安那-得克萨斯（LATEX）广阔大陆架上的埃克曼建立而产生的。相比之下，飓风登陆时，主要的浪潮主要是低压和最大的风，它们沿着垂直于海岸的路径流动。发现跨岸埃克曼设置对底部边界层（BBL）动力学特别是阻力系数高度敏感。考虑到事实，即墨西哥湾富含泥浆，在天气晴朗的情况下，近床层的流动通常非常微弱，一个合理的假设是，在暴风雨期间，悬浮泥沙引起的密度分层很可能普遍存在于底部边界层。将包括泥沙诱发分层效应的泥沙输送模型和波流底部边界层子模型与非结构化网格环流和风波模型（SELFE-WWM II）耦合，以模拟飓风艾克期间的先兆。模型结果表明，底部边界层动力学对整个架子的速度转向和Ekman设置都有重要影响。；在缅因州海湾研究中，应用了高分辨率耦合SELFE-WWM II模型在Scituate港口，波士顿南部的一个小而浅的沿海港口。该研究的关键问题是反复发生的洪水，这与在非复活节事件中风波所起的作用有关。由于Scituate中的观测数据有限，因此将SELFE的模型结果与FVCOM的模型结果进行了比较。主要研究结果概括如下：（1）诺尔复活节产生的风波可通过增加其大小并改变其方向而对沿海水流产生深远的影响；（2）在港口内的平均水位保持不变的情况下，当包括风浪时，穿过港口口的总运输量增加；（3）当包括风浪时，主要在港口北部和南部盆地的总淹没面积确实增加了。有一个问题是，为什么在增加淹没面积的同时，将风浪包括在内并不会导致港口内的平均水位发生变化。可能的解释是，这种缺乏影响的原因可能是斯托克斯输运量很小，波浪形成引起的水位上升被浅水区淹没面积的扩大所补偿。

著录项

  • 作者

    Teng, Yi-Cheng.;

  • 作者单位

    The College of William and Mary.;

  • 授予单位 The College of William and Mary.;
  • 学科 Physical Oceanography.;Meteorology.
  • 学位 Ph.D.
  • 年度 2012
  • 页码 300 p.
  • 总页数 300
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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