SGER: Transient Shelf Response to the Hurricane Wilma's Impact

SGER：对飓风威尔玛影响的短暂陆架响应

• 批准号: 0617130
• 负责人: Alexander Yankovsky
• 金额: $ 7.96万
• 依托单位: Nova Southeastern University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-03-01 至 2006-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0617130&HistoricalAwards=false
• 关键词: SGER; Transient; Shelf; Response; Hurricane

The frequency and severity of hurricane activity has risen sharply over the last few years. Several major hurricanes hit the US Southeast coast in the 2004 and 2005 seasons, with the impacts from Katrina and Wilma being among the costliest in the US history. Typically, the storm surge predictions are focused on local dynamics associated with the wind-induced onshore drift and the wave action. However, the evolution of storm surge also includes an alongshore propagation of the coastally trapped wave (CTW) pulse. Linear theories predict that in such a case the strongest response occurs downstream (in the sense of Kelvin wave propagation) and later in time relative to the location and moment of the landfall. This notion is consistent with the events in New Orleans, when the protective levies were overwhelmed a few hours after the Hurricane Katrina's landfall some distance upstream, on the Mississippi coast.Unique and detailed observations of sea level and barometric pressure along the Southwest Florida coast collected during Hurricane Wilma's landfall in October 2005 will be analyzed to delineate the coastally trapped wave (CTW) pulse propagation, dispersion and decay as it leaves the forcing region and moves downstream (northward). While the observational array was not designed to capture the complex hydrodynamics of the storm surge, it occupied an optimal position for observing the hurricane-generated CTW pulse.. These data will also be used for tuning-up the primitive equation model in order to conduct a process-oriented study of the hurricane's impact on the wide and shallow shelf. The data set consists of weeklong time series of storm surge (S) and barometric pressure (B) measured by the USGS Florida Integrated Science Center at approximately 30 locations. The survey area spanned more than 100 km alongshore with the instruments deployed both on the coastline and in the inlets/estuaries. These data will be augmented with the existing NOAA wind and sea level measurements. The atmospheric pressure data will be used in order to determine a temporal and spatial evolution of the wind forcing: the available time series of wind will be extrapolated by applying the structure of atmospheric pressure variations. Detailed barometric pressure measurements will be also applied to accurately adjust the sea level data and thus to detect the CTW pulse evolution along the coastline. The CTW pulse amplitude will be determined by using data from the exposed coastline only, while the phase will be estimated based both on data from the coastline and from the inlets. The latter will be adjusted in time by allowing the signal propagation from the mouth inland at a speed of a long gravity wave. The observations will be reproduced in the model by applying the observed forcing and tuning the bottom stress and horizontal eddy "viscosity" coefficients in order to obtain a realistic propagation speed and amplitude of the storm surge. The shelf topography will be uniform alongshore, except for the upstream boundary, where the shelf width will diminish abruptly, thus mimicking the southern tip of Florida. The role of dispersion, friction and nonlinearity will be systematically studied by conducting realistic model runs with the observed wind forcing and complimentary model runs with the same initial disturbance (induced by the hurricane) but traveling as a free wave pulse with much reduced friction, and also as a pulse of the same spatial-temporal structure but with a smaller amplitude (allowing linear dispersion). In subsequent model experiments, the coastline feature will also be placed downstream, representing the conditions of Hurricane Katrina (i.e., protruding Mississippi delta). Broader Impacts: The results of data analysis and numerical experiments will reveal the importance of dispersion, nonlinearity, frictional decay and topographic variations in the alongshore evolution of storm surge driven by a hurricane landfall. The results will also improve our understanding and predictability of hurricane-induced flooding with a focus on vulnerability of the downstream areas.

在过去的几年中，飓风活动的频率和严重程度急剧上升。在2004年和2005年，几起主要的飓风袭击了美国东南海岸，卡特里娜飓风和威尔玛的影响是美国历史上最昂贵的。通常，风暴潮预测集中在与风诱导的陆上漂移和波动作用相关的局部动力上。但是，风暴潮的演变还包括沿海被困波（CTW）脉冲的沿岸繁殖。线性理论预测，在这种情况下，最强的响应发生在下游（从开尔文波传播的意义上），随着时间的时间相对于登陆的位置和力矩。这个概念与新奥尔良的事件一致，当保护性征税在卡特里娜飓风的登陆后几个小时被压倒性的征收，在密西西比州海岸上游一些距离。在威尔玛飓风期间，将分析2005年10月的登陆，以描绘出沿海被困的波（CTW）脉冲传播，分散和衰变，因为它离开强迫区域并向下移动（北向）。虽然观察阵列并非旨在捕获风暴潮的复杂流体动力学，但它占据了观察飓风生成的CTW脉冲的最佳位置。这些数据也将用于调整原始方程模型以进行调整以进行操作以过程为导向的研究对飓风对宽阔和浅层架子的影响。数据集包括由USGS佛罗里达综合科学中心在大约30个地点测量的为期一周的风暴潮（S）和气压（B）。调查区域跨越了沿海沿岸和河口/河口的仪器跨越沿岸超过100公里。这些数据将通过现有的NOAA风能和海平面测量来增强。将使用大气压力数据来确定风力强迫的时间和空间演化：可用的风序序列将通过应用大气压力变化的结构来推断。还将应用详细的气压测量值，以准确调整海平面数据，从而检测沿海岸线的CTW脉冲演化。 CTW脉冲振幅将仅通过使用裸露的海岸线的数据来确定，而该相位将基于海岸线和入口的数据估计。后者将通过允许以长重力波的速度从口腔内陆传播信号传播来及时调整。通过应用观察到的强迫和调谐底部应力和水平涡流“粘度”系数，以获得现实的传播速度和风暴潮的振幅，可以在模型中复制观察结果。除上游边界外，架子的地形将是统一的沿岸，那里的架子宽度会突然减少，从而模仿佛罗里达州的南端。分散，摩擦和非线性的作用将通过进行现实的模型运行，并以相同的初始干扰（由飓风引起），但作为自由波脉冲以大量降低的摩擦和摩擦降低的自由波脉冲运行，可以系统地研究逼真的模型。也是相同时空结构的脉冲，但幅度较小（允许线性分散）。在随后的模型实验中，海岸线特征还将放置在下游，代表卡特里娜飓风的条件（即突出的密西西比三角洲）。更广泛的影响：数据分析和数值实验的结果将揭示分散，非线性，摩擦衰减和地形变化的重要性，这是由飓风登陆所驱动的风暴潮发展的沿岸演变的重要性。结果还将提高我们对飓风引起的洪水的理解和可预测性，重点关注下游地区的脆弱性。