Semidiurnal Perturbations to Storm Surges on the U.S. Eastern Seaboard

美国东海岸风暴潮的半日扰动

• 批准号: 1332718
• 负责人: Arnoldo Valle-Levinson
• 金额: $ 39.94万
• 依托单位: University of Florida
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-08-15 至 2018-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1332718&HistoricalAwards=false
• 关键词: Semidiurnal; Perturbations; Storm; Surges; U.S.

Semidiurnal perturbations modified the non-tidal surges of hurricanes Sandy (2012) and Irene (2011) which affected the entire U.S. eastern seaboard. In the South Atlantic Bight, the amplitude of the perturbations reached up to 50-60% of the total surge amplitude. In general, semidiurnal perturbations become evident when predicted water levels are subtracted from observed water levels. A response of such tide-surge interaction is to modify the timing of tidal low and high water, which is expected to be different from nearly progressive to nearly standing tides. This project seeks to advance understanding of the processes that trigger semidiurnal perturbations on storm surges and that determine the size of the perturbations. Atmospheric forcing can disturb the surge through direct surface stress and by inducing additional bottom stress and tidal stress. The relative contribution of each stress needs improved understanding. Specific objectives of this investigation are to determine a) whether semidiurnal perturbations appear under other tropical storms and under extratropical storms, b) the relative size of the dynamic agents associated with the perturbations, and c) the atmospheric and tidal forcing thresholds that produce them. Specific objectives will be addressed with observations from tidal and meteorological stations along the U.S. eastern coast, and with realistic and process-oriented numerical simulations.Intellectual Merit: In recent decades, coastal areas worldwide have been affected by storms that cause severe flooding, damage to buildings, and beach erosion. Storm-tide interactions can produce the highest storm-related levels at times not linked to high tide but still at semidiurnal periodicities. It is therefore necessary to understand the behavior of semidiurnal perturbations triggered by storms in order to improve forecasts and warning systems of storm surges. This project will try to answer several key questions: Do semidiurnal perturbations occur in every storm that moves along the eastern US? Do semidiurnal perturbations also occur during nor'easters? What are the dynamics associated with these perturbations? Are there atmospheric forcing thresholds below which these perturbations vanish? Do perturbations depend on the tidal amplitude? Does the peak in semidiurnal perturbations develop consistently in one phase of the tidal cycle? Clearly, there is a need to understand appropriate conditions for triggering semidiurnal perturbations on the surge. Findings generated from the study will help understand the causes for the appearance of high frequency (periods smaller than the inertial period) perturbations, semidiurnal residuals, which modify storm surges.Broader Impacts: This project will study a phenomenon that can affect the entire U.S. eastern seaboard. Because semidiurnal perturbations can reach amplitudes of up to 50-60% of the total surge signal in the South Atlantic Bight, it is imperative to include tide-surge interactions. These interactions will also affect the timing of maximum surge, relative to high tide. Probability density functions related to arrival of storm surges will thus be affected by semidiurnal residuals. Better understanding of these perturbations will help to refine storm surge predictions and risk analysis for the entire eastern U.S. seaboard. The project will support one graduate student, one undergraduate, through semester-long research experiences, and one high school student through summer internships. The high school student will be recruited among minority groups among high schools in Gainesville, Florida. Results derived from this project will be presented to K-12 audiences and will be incorporated in classes taught by the PIs at the University of Florida. The involvement of both PIs enhances the participation of underrepresented groups in science.

半腐烂的扰动改变了飓风桑迪（2012）和Irene（2011）的非潮汐潮，影响了整个美国东部沿海地机。在南大西洋的距离，扰动的幅度最高可达到总振幅幅度的50-60％。通常，当观察到的水位从观察到的水位中减去预测的水位时，半潮湿的扰动变得明显。这种潮汐相互作用的响应是修改潮汐低水和高水的时机，这有望从几乎渐进到几乎站立的潮汐中不同。该项目旨在提高人们对触发半职扰动的过程的理解，并确定扰动的大小。大气强迫会通过直接表面应力和诱发额外的底部应力和潮汐应力来干扰浪涌。每种压力的相对贡献需要改善理解。 该研究的具体目标是确定a）半腐烂的扰动是否出现在其他热带风暴下和热带风暴下，b）与扰动相关的动态剂的相对大小以及c）大气和潮汐强迫产生它们的阈值。特定目标将通过美国东部沿海潮汐和气象站的观察以及面向过程的数值模拟进行解决。Intlectual-Ferior：近几年来，全世界的沿海地区受到暴风雨的影响，这些风暴受到严重洪水，对建筑物的损害以及海滩侵蚀的风暴。风暴潮的相互作用有时会产生与风暴相关的水平最高的水平，而不是与潮汐相关，但仍处于半间周期。因此，有必要了解暴风雨触发的半潮汐扰动的行为，以改善风暴潮的预测和警告系统。该项目将尝试回答几个关键问题：在沿美国东部的每一次风暴中，半潮汐扰动是否发生？在诺伊斯特人期间还会发生半职扰动吗？与这些扰动有关的动态是什么？这些扰动消失的大气强迫阈值是否存在？扰动是否取决于潮汐振幅？在潮汐周期的一个阶段，半潮湿扰动中的峰是否会始终如一？显然，有必要了解适当的条件，以触发激增的半腐烂扰动。该研究产生的发现将有助于了解高频出现（比惯性时期小的周期）扰动，半潮湿残留物的原因，从而改变了风暴的影响：Boader的影响：该项目将研究一种可能影响整个美国东部海面的现象。由于半潮湿的扰动可以达到南大西洋临时总电涌信号的50-60％的幅度，因此必须包括潮汐相互作用。相对于高潮，这些相互作用还将影响最大浪涌的时间。因此，与风暴潮的到来有关的概率密度功能将受到半潮汐残留物的影响。更好地了解这些扰动将有助于完善整个美国东部沿海地区的风暴浪潮预测和风险分析。该项目将通过长期的研究经验来支持一名研究生，一个本科生，并通过暑期实习来支持一名高中生。高中生将在佛罗里达州盖恩斯维尔的高中中的少数群体中招募。该项目得出的结果将呈现给K-12受众，并将在佛罗里达大学PIS教授的课堂中纳入。两种PI的参与都增强了代表性不足的群体参与科学的参与。