Importance of wave age and resonance in storm surges: The case Xynthia, Bay of Biscay
Importance of wave age and resonance in storm surges: The case Xynthia, Bay of Biscay
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DOI：
10.1016/j.ocemod.2011.11.001
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发表时间：
2012
期刊：
影响因子：
3.2
通讯作者：
X. Bertin;N. Bruneau;Jean-François Breilh;A. Fortunato;M. Karpytchev
中科院分区：
文献类型：
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作者：
X. Bertin;N. Bruneau;Jean-François Breilh;A. Fortunato;M. Karpytchev
这项研究旨在回溯和分析与辛西亚相关的风暴潮，辛西亚是一个中纬度低压，于2010年2月27日至28日严重袭击了法国中部的比斯开湾。造成人员伤亡和财产损失的主要原因是风暴潮造成的，风暴潮在局部地区超过1.5米，并在大潮到来时达到峰值，导致低洼海岸被淹。基于非结构网格环流模式SELFE和谱波模式WaveWatchIII，开发了一个新的风暴潮数值模拟系统。在东北大西洋的建模系统，并导致潮汐和波浪预测的顺序的3%和15%的误差，分别。比斯开湾沿着也对与辛西亚相关的风暴潮进行了很好的预测，仅将风暴潮峰值略微低估了3- 8%。通过数值试验，分析了风暴潮发展的物理过程，首次揭示了风场通过Ekman建立过程引起大部分水位异常。计算风应力的波浪依赖和二次参数化之间的比较表明，风暴潮强烈放大的陡峭和年轻的风浪的存在，与他们的快速发展，在比斯开湾的限制获取。在比斯开湾中部，登陆时观测到的和预测的水位异常都显示出16小时的振荡，振幅高达0.2米（浪涌峰值的10-20%）。分析架共振模型和数值实验表明，所观察到的振荡周期对应于比斯开湾中部大陆架的共振模式。它的结论是，这些振荡源于水位扰动和大陆架之间的相互作用，这种现象预计将在其他地方有关沿着世界海岸线。
This study aims to hindcast and analyze the storm surge associated with Xynthia, a mid-latitude depression that severely hit the French central part of the Bay of Biscay on the 27–28th of February 2010. The main losses in human lives and damages were caused by the associated storm surge, which locally exceeded 1.5m and peaked at the same time as a high spring tide, causing the flooding of low-lying coasts. A new storm surge modeling system was developed, based on the unstructured-grid circulation model SELFE and the spectral wave model WaveWatchIII. The modeling system was implemented over the North-East Atlantic Ocean and resulted in tidal and wave predictions with errors of the order of 3% and 15%, respectively. The storm surge associated with Xynthia was also well predicted along the Bay of Biscay, with only a slight underestimation of the surge peak by 3–8%. Numerical experiments were then performed to analyze the physical processes controlling the development of the storm surge and revealed firstly that the wind caused most of the water level anomaly through an Ekman setup process. The comparison between a wave-dependant and a quadratic parameterization to compute wind stress showed that the storm surge was strongly amplified by the presence of steep and young wind-waves, related to their rapid development in the restricted fetch of the Bay of Biscay. In the central part of the Bay of Biscay, both observed and predicted water level anomalies at landfall displayed ∼6h oscillations, with amplitudes of up to 0.2m (10–20% of the surge peak). An analytical shelf resonance model and numerical experiments demonstrated that the period of the observed oscillations corresponds to the resonant mode of the continental shelf in the central part of the Bay of Biscay. It is concluded that these oscillations originate from the interactions between the water level perturbation and the continental shelf and this phenomenon is expected to be relevant at other places along the world’s coastlines.