Increasing Wave Energy Moves Arctic Continental Shelves Toward a New Future
Increasing Wave Energy Moves Arctic Continental Shelves Toward a New Future
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波浪能的增加使北极大陆架走向新的未来
DOI：
10.1029/2021jc018374
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发表时间：
2022
期刊：
影响因子：
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通讯作者：
Nienhuis, Jaap
中科院分区：
文献类型：
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作者：
Malito, John;Eidam, Emily;Nienhuis, Jaap
北极大陆架，包括阿拉斯加博福特大陆架(ABS)，正在经历海冰覆盖面积的下降，导致越来越多的海洋国家和海岸侵蚀。在这项研究中，我们研究了ABS对海浪能量增加的形态响应，以及陆架剖面调整如何改变向海岸传播的海浪能量。我们使用Delft3D开发了一个二维跨陆架地貌动力学模型，并测试了陆架对RCP8.5气候变化情景下预测的当前海浪气候和未来北极海浪气候的响应。对相对陡峭(亚肯色州弗拉克斯曼岛，坡度0.0008)和平坦(亚肯色州哈里森湾，坡度0.0003)的跨陆架剖面进行了持续1000年的模拟。我们发现，未来海浪的形态演变和调节主要取决于现有的陆架形态。在较陡峭的剖面上，RCP 8.5波在0-15米水深驱动泥沙侵蚀，在15-30米水深驱动泥沙再沉积。在1000多年的时间里，沉积物从陆架内侧到中部的这种重新分配导致2米等深线的波高降低了7.6%。这种形态调整代表了一种调节反馈，在这种反馈中，中间陆架的变浅导致到达内陆架的波衰减。相反，横跨更平坦和更宽的哈里森湾断面的有效波浪衰减限制了两种波浪气候下的跨陆架输送和地形变化。总之，我们的结果表明，对日益增长的北极海浪气候的响应，海岸变化可能取决于陆架形态，在某些地区，甚至可以通过形态调整来缓解。
Arctic continental shelves, including the Alaskan Beaufort Shelf (ABS), are experiencing declines in sea ice coverage leading to increasingly energetic sea states and coastal erosion. In this study we investigated the morphologic response of the ABS to increasing wave energy, and how shelf profile adjustments modify wave energy propagating toward the coast. We developed a 2D cross‐shelf morphodynamic model using Delft3D and tested shelf response to a present‐day wave climate and a future Arctic wave climate projected under the RCP8.5 climate‐change scenario. Simulations lasting 1000 years were conducted for relatively steep (Flaxman Island, AK, slope 0.0008) and flat (Harrison Bay, AK, slope 0.0003) cross‐shelf profiles. We found that morphologic evolution and regulation of future waves depends primarily on existing shelf morphology. On the steeper profile, RCP 8.5 waves drove sediment erosion at 0–15 m water depth and redeposition at 15–30 m water depth. Over 1000 years, this redistribution of sediment from the inner to middle shelf resulted in a 7.6% reduction in wave heights at the 2 m isobath. This morphologic adjustment represented a regulatory feedback in which shallowing of the middle shelf led to attenuation of waves reaching the inner shelf. In contrast, effective wave attenuation across the flatter and wider Harrison Bay section limited cross‐shelf transport and morphologic change under both wave climates. Together our results suggest that coastal changes in response to the growing Arctic wave climate may be dependent on shelf morphology, and even mitigated in some regions by morphologic adjustment.