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Zhang Chenguang,Li Chunyan. 2019. Effects of hurricane forward speed and approach angle on storm surges: an idealized numerical experiment. Acta Oceanologica Sinica, 38(7):48-56
Effects of hurricane forward speed and approach angle on storm surges: an idealized numerical experiment
台风移行速度与登陆角度对风暴潮的影响:一个理想模型数值实验
Received:November 19, 2018  
DOI:10.1007/s13131-018-1081-z
Key words:storm surge experiments  FVCOM  hurricane forward speed  approach angle  Kelvin waves  forced and free surge interactions
中文关键词:  风暴潮数值实验  FVCOM  台风移行速度  台风登陆角度  开尔文波  强迫波与自由波的相互作用
基金项目:The National Key R & D Project under contract No. 2017YFC1404201.
Author NameAffiliationE-mail
Zhang Chenguang Department of Oceanography and Coastal Sciences, Louisiana State University, Baton Rouge LA 70803, USA  
Li Chunyan Department of Oceanography and Coastal Sciences, Louisiana State University, Baton Rouge LA 70803, USA cli@lsu.edu 
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Abstract:
      The effects of hurricane forward speed (V) and approach angle (θ) on storm surge are important and a systematic investigation covering possible and continuous ranges of these parameters has not been done before. Here we present such a study with a numerical experiment using the Finite Volume Community Ocean Model (FVCOM). The hurricane track is simplified as a straight line, such that V and θ fully define the motion of the hurricane. The maximum surge is contributed by both free waves and a forced storm surge wave moving with the hurricane. Among the free waves, Kelvin-type waves can only propagate in the down-coast direction. Simulations show that those waves can only have a significant positive storm surge when the hurricane velocity has a down-coast component. The optimal values of V and θ that maximize the storm surge in an idealized semi-circular ocean basin are functions of the bathymetry. For a constant bathymetry, the maximum surge occurs when the hurricane approaches the coast from the normal direction when the free wave generation is minimal; for a stepped bathymetry, the maximum surge occurs at a certain acute approach angle which maximizes the duration of persistent wind forcing; a step-like bathymetry with a sloped shelf is similar to the stepped bathymetry, with the added possibility of landfall resonance when the free and forced waves are moving at about the same velocity. For other cases, the storm surge is smaller, given other parameters (hurricane size, maximum wind speed, etc.) unchanged.
中文摘要:
      台风的移行速度(V)和登陆角(θ)对风暴潮有重要的影响,而之前并未见有涵盖这两个量的整个参数空间的系统性研究。在这里,我们用有限体积海洋模型FVCOM做了一个这样的数值试验。在台风中心移行轨迹简化为直线的条件下,Vθ便可以完全描述台风的运动。最大风暴潮是由自由波和随台风移动的强迫波的叠加所造成的。在自由波中,开尔文型波只能在岸线的左边单向向前传播(面向波行方向,海岸在右边)。模拟结果表明,只有当台风速度具有开尔文波行方向分量时,这些波才可以产生显著的正风暴潮。在理想化的海盆中,导致最大风暴潮的Vθ的值是水深的函数。对于恒定水深,台风从法线方向接近海岸时会发生最大风暴潮,同时产生的自由波最小;当陆架水深是阶梯分布时,最大风暴潮发生在某个锐角登陆角,它可以最大化风力的持续时间;具有倾斜陆架的阶梯水深类似于阶梯水深的情况,但是增加了自由波和强迫波以大致相同速度移动的共振的可能。对于其它情况,风暴潮则较小(在保持其他参数比如台风大小,最大风速等不变的情况下)。
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