Observations of nearshore crescentic sandbars
Observations of nearshore crescentic sandbars
复制标题
近岸新月形沙洲的观测
DOI：
10.1029/2003jc002214
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发表时间：
2004
影响因子：
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通讯作者：
R. Holman
中科院分区：
文献类型：
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作者：
I. V. Enckevort;B. Ruessink;G. Coco;Kazuo Suzuki;Ian L Turner;N. Plant;R. Holman
[1]新月形沙洲的时间和空间变异性进行了分析，每小时的长期（几个月）的视频观测收集在四个禁止网站和定性比较的时间和空间变异性预测的假设支持现有的方法和模型新月形酒吧的形成（边缘波模板模型，线性稳定性分析，非线性模型）。来自美国北卡罗来纳州达克和日本九州宫崎的单栅栏海滩，以及来自澳大利亚昆士兰州北方黄金海岸和荷兰诺德韦克的双栅栏海滩的观测结果表明，新月形沙洲波长和振幅随时间和空间的变化非常普遍。例如，在任何时刻，最小和最长的新月杆的波长可以相差2倍。波长和振幅的时间变化是由单个新月体的合并和分裂引起的，导致新月体沙洲系统的“最终”配置与初始配置非常不同。黄金海岸的数据表明，这些本质上非线性的相互作用是一种尝试的新月形酒吧系统的自组织成一个更统一的模式，分裂通常是局限于最长的新月形酒吧观察，而合并通常结合成一个更长的酒吧最小的新月形酒吧。所观察到的空间和时间的新月形酒吧的行为与从边缘波模板模型预测的行为定性对比，并意味着线性稳定性模型的预测技巧是有限的。非线性模型可能更适合对这些实地观察的比较，提出了几项建议，以改善这些模型，从而促进数据模型的比较。
[1] The temporal and spatial variability of crescentic sandbars is analyzed with hourly long-term (months) video observations collected at four barred sites and are qualitatively compared to the temporal and spatial variability predicted by hypotheses underpinning existing approaches and models for crescentic bar formation (edge-wave template model, linear stability analysis, and nonlinear models). The observations, coming from the single barred beaches at Duck (North Carolina, USA) and Miyazaki (Kyushu, Japan), and from the double-barred beaches at the northern Gold Coast (Queensland, Australia) and Noordwijk (Netherlands), show that crescentic sandbar wavelength and amplitude variations over space and time are very common. For instance, at any moment in time, the wavelength of the smallest and longest crescentic bar can differ by a factor of 2. Temporal changes in wavelength and amplitude result from merging and splitting of individual crescents, causing the “final” configuration of a crescentic sandbar system to be very different from the initial configuration. The Gold Coast data indicate that these intrinsically nonlinear interactions are an attempt of the crescentic bar system to self-organize into a more uniform pattern, as splitting is usually confined to the longest crescentic bar observed, whereas merging usually combines the smallest crescentic bars into a longer bar. The observed spatial and temporal crescentic bar behavior contrasts qualitatively with behavior predicted from the edge-wave template model and implies that the predictive skill of linear stability models is limited. Nonlinear models are potentially better suited for a comparison against these field observations; several suggestions to improve these models, and hence to facilitate a data-model comparison, are made.