Infragravity wave generation on shore platforms: Bound long wave versus breakpoint forcing
Infragravity wave generation on shore platforms: Bound long wave versus breakpoint forcing
复制标题
岸上平台上的次重力波产生：束缚长波与断点强迫
DOI：
10.1016/j.geomorph.2019.106880
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发表时间：
2020
期刊：
影响因子：
3.9
通讯作者：
Poate T
中科院分区：
文献类型：
--
作者：
Poate T
海岸平台是岩石海岸线上无处不在的地貌特征，表现出从缓坡到半水平的各种形式，并带有低潮悬崖。它们通常位于侵蚀海岸悬崖的前方，通过消散波浪能量，特别是在高能波浪条件下，发挥着重要的天然海岸保护作用。海浪破碎时，海浪能量会消散，但入射波能转移到更低的频率，从而产生亚重力波，可以使大量的波能持续到海岸线上。海岸线上的这种残留波动可以进行地貌工作，例如通过直接冲击悬崖面，但也可以清除悬崖脚趾碎片。产生次重力波运动的主要机制有两种--群限长波和断点强迫--目前尚不清楚这些机制中的哪一种在岸上平台上运行。本文利用在英国的一个倾斜平台和新西兰的一个次水平平台上收集的现场资料，在数值模拟的支持下，证明了群控长波机制在倾斜平台上是最重要的，而断点强迫在次水平平台上占主导地位。我们的结果还表明，倾斜平台上的亚重力波动比次水平平台上的波动能量更大，这意味着后者可能对海岸悬崖提供更好的保护。然而，特定地点的因素，特别是与潮位和平台坡度有关的平台高度，在岸上平台的波浪转换过程中起着关键作用，需要更多的现场数据和建模工作来加强我们对这些过程的理解，特别是在极端波浪条件下收集的数据(HS>；5米)。
Shore platforms are ubiquitous morphological features along rocky coastlines and display a spectrum of forms from gently-sloping to sub-horizontal with a low tide cliff. They generally front eroding coastal cliffs and play an important natural coastal protection role by dissipating wave energy, especially during energetic wave conditions. Sea-swell wave energy dissipates during wave breaking, but the transfer of incident wave energy to lower frequencies, resulting in infragravity waves, can enable significant amounts of wave energy to persist up to the shoreline. This residual wave motion at the shoreline can carry out geomorphic work, for example by directly impacting the cliff face, but also for removing cliff-toe debris. There are two main mechanisms for generating infragravity wave motion – group bound long waves and breakpoint forcing – and it is not known which of these mechanisms operate on shore platforms. Here we show, using field data collected at a sloping platform in England and a sub-horizontal platform in New Zealand, and supported by numerical modelling, that the group bound long wave mechanism is most important on sloping platforms, whereas breakpoint forcing dominates on sub-horizontal platforms. Our results also suggest that the infragravity wave motion on the sloping platform is somewhat more energetic than that on the sub-horizontal platform, implying that the latter type of platform may provide better protection to coastal cliffs. However, site-specific factors, especially platform elevation with respect to tidal level and platform gradient, play a key role in wave transformation processes on shore platforms and more field data and modelling efforts are required to enhance our understanding of these processes, especially collected under extreme wave conditions (Hs> 5 m).
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DOI：
10.1098/rspa.2002.0962
发表时间：
2002-09
期刊：
Proceedings of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences
影响因子：
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作者：
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通讯作者：
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DOI：
--
发表时间：
2017
期刊：
影响因子：
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