Large-Scale Edge Waves Generated by Hurricane Landfall

学术价值：飓风引发的沿海地区的洪水和洪水是一个重要的社会问题。在直接登陆区以外和登陆后几个小时内，可以由自由传播的波脉冲引起严重的洪水。这些案件确实发生在过去。对2005年10月24日在佛罗里达州西海岸登陆的威尔玛飓风引起的风暴潮的观测显示，随着威尔玛向内陆移动，风暴潮不再由风的强迫作用维持，形成了一个波动脉冲。在潮位资料中，波脉冲的高度超过1.5m，但由于其在退潮时传播，在潮汐测量中被遮挡住了。该波脉冲的持续时间为6小时，传播速度在10-25m S-1范围内变化，反映了初始扰动的演化过程。波脉冲被识别为具有大空间和时间尺度的边缘波。由飓风在大陆架上引发的这种持续时间相对较短的海浪以前从未报道过。最有可能的是，它们逃过了检测，因为由NOAA和USGS维持的标准观测网络中的稀疏空间分辨率无法解析它们的相位传播。相反，以前的研究集中在周期与惯性相当或更长的较低频率的海岸滞留波(CTW)上，这些波被认为是热带气旋产生的主要波型。本项目将通过面向过程的数值模拟方法研究飓风诱发的边缘波的产生和近岸演变。更具体地说，将讨论以下问题：-飓风登陆产生边缘波的最有利条件是什么？飓风的大小、强度、平移速度和轨迹，以及陆架地形的作用，都将被勾勒出来。-哪些地形形式会导致边缘波的局部放大？地形变化大(陆架变宽/变窄、海岸线弯曲等)的影响和较小的地物(入海口、入海口、海角等)将进行系统的研究。--边缘波消散的机制是什么？耗散主要是与海底摩擦有关，还是与近海能量辐射有关？更广泛的影响：该项目的成果将在减灾、防灾和开发预警系统等领域应用于国家和区域安全。这一结果对于海岸带的管理和保护以及海上作业也将是重要的。该项目将资助一名研究生。

Intellectual merit:The hurricane-induced surge and flooding in the coastal areas is an important societal problem. Severe flooding outside the immediate landfall area and a few hours after the landfall can be caused by a freely propagating wave pulse. The cases indeed occurred in the past. The observations of the storm surge induced by Hurricane Wilma landfall on the West Coast of Florida on October 24, 2005 revealed a formation of a wave pulse as Wilma moved inland and the surge was no longer sustained by the wind forcing. The height of the wave pulse exceeded 1.5 m in de-tided sea level data, but it was somewhat obscured in the surge measurements because of its propagating during the low tide. The duration of this wave pulse was ~6 hrs and the propagation speed varied within a range of 10-25 m s-1 indicating an evolution process of the initial disturbance. The wave pulse is identified as an edge wave with large spatial and temporal scales. Such relatively short-lasting waves induced by a hurricane on the continental shelf were not reported before. Most likely, they escaped detection, because a sparse spatial resolution in the standard observational network maintained by NOAA and USGS cannot resolve their phase propagation. Instead, the previous studies were focused on lower-frequency coastally trapped waves (CTW) with periods comparable to or longer than the inertial, which were thought to be prevailing wave modes generated by tropical cyclones. This project will investigate the generation and alongshore evolution of the hurricane-induced edge waves by means of process-oriented numerical modeling. More specifically, the following questions will be addressed: - What are the most favorable conditions for the edge wave generation by a hurricane landfall? The roles of the hurricane size, strength, translation speed and trajectory, as well as the role of shelf topography, will be delineated. - What topographic forms induce the local amplification of the edge waves? The effects of large topographic variations (widening/narrowing shelf, bending coastline, etc.) and smaller features (inlets, estuaries, capes, etc.) will systematically be studied. - What are the mechanisms of the edge wave dissipation? Is the dissipation mostly related with the bottom friction or with the offshore energy radiation? Broader impacts:The results of the project will have applications to national and regional security in such areas as hazard mitigation, disaster prevention, and the development of early warning systems. The results will also be important for coastal zone management and protection, as well as for maritime operations. One graduate student will be supported by this project.