Bed shear stress in the southern North Sea as an important driver for suspended sediment dynamics
Bed shear stress in the southern North Sea as an important driver for suspended sediment dynamics
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DOI：
10.1007/s10236-008-0171-4
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发表时间：
2009-04
期刊：
影响因子：
2.3
通讯作者：
E. Stanev;M. Dobrynin;A. Pleskachevsky;S. Grayek;H. Günther
中科院分区：
文献类型：
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作者：
E. Stanev;M. Dobrynin;A. Pleskachevsky;S. Grayek;H. Günther
本文讨论了沿海地区沉积动力驱动因素的空间和时间模式。基本假设是局部过程占主导地位。重点讨论了北海南部的床面切应力对沉积-沉积和再悬浮-侵蚀的基本控制作用。波浪引起的床面剪切应力是使用基于以下概念的模型来制定的：与表面波相关的湍流动能是轨道速度的函数，后者取决于波高和周期，以及水深。表面波参数取自海浪谱模型WAM（波浪模型）的模拟。采用汉堡陆架海洋模式（Hamburg Shelf Ocean Model）模拟了与海流有关的底床切应力。有效波高，由于波浪和水流的床面剪切应力，进行经验正交函数（ERF）分析。已经发现，有效波高的Δ-1表示在浅滩上的有效波高的减小，并且由于取流限制，沿沿着的有效波高减小。高阶模态是跷跷板状的，并且结合起来，显示出以盆地中部为中心的盆地尺度旋转模式。床面剪应力的第二次和第三次变化也有类似的变化。从MERIS卫星数据的悬浮物的表面浓度进行了分析和比较，对床面剪切应力的统计特性。结果表明，泥沙的水平分布在很大程度上可以用局部剪应力来解释。然而，在一些地区，如多格浅滩，底部可再悬浮沉积物的可用性非常重要。
This paper addresses the spatial and temporal patterns of drivers for sediment dynamics in coastal areas. The basic assumption is that local processes are dominating. The focus is put on the bed shear stress in the southern part of North Sea giving the basic control for deposition–sedimentation and resuspension–erosion. The wave-induced bed shear stress is formulated using a model based on the concept that the turbulent kinetic energy associated with surface waves is a function of orbital velocity, the latter depending on the wave height and period, as well as on the water depth. Parameters of surface waves are taken from simulations with the wave spectrum model WAM (wave model). Bed shear stress associated with currents is simulated with a 3D primitive equation model, Hamburg Shelf Ocean Model. Significant wave height, bed shear stress due to waves and currents, is subjected to empirical orthogonal functions (EOF) analysis. It has been found that the EOF-1 of significant wave height represents the decrease of significant wave height over the shallows and, due to fetch limitation, along the coastlines. Higher order modes are seesaw-like and, in combination, display a basin-scale rotational pattern centred approximately in the middle of the basin. Similar types of variability is also observed in the second and third EOF of bed shear stress. Surface concentrations of suspended matter derived from MERIS satellite data are analysed and compared against statistical characteristics of bed shear stress. The results show convincingly that the horizontal distribution of sediment can, to a larger extent, be explained by the local shear stress. However, availability of resuspendable sediments on the bottom is quite important in some areas like the Dogger Bank.