Phase relationships between fine sediment suspensions and tidal currents in coastal seas
Phase relationships between fine sediment suspensions and tidal currents in coastal seas
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DOI：
10.1029/2001jc001269
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发表时间：
2002-10
影响因子：
--
通讯作者：
S. Bass;J. Aldridge;I. McCave;C. Vincent
中科院分区：
文献类型：
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作者：
S. Bass;J. Aldridge;I. McCave;C. Vincent
[1] 在陆架和沿海水域，细悬浮沉积物浓度的点测量通常显示出相对于当地洋流强迫的相位和频率差异。相移通常归因于潮汐平流和粘性沉积物的缓慢沉降速度。研究了在英格兰东海岸附近获得的潮汐流速度和近床泥浆浓度之间的相位关系。引入了一个简单的深度平均平流扩散模型，用于探索沉降、平流和局部侵蚀的相对变化对悬浮事件时间演化的影响。该模型包括两个源项：与当前速度同相的局部再悬浮以及与潮汐位移同相的水平梯度的平流。结合沉降（或下沉）项分别在平流或再悬浮项中引入负相移或正相移。沉降项解释了悬浮液的垂直结构，并且当近床浓度和沉积迅速增加时，沉降项在松弛水中变得很重要。将模型结果与悬浮泥浆浓度数据进行比较，以帮助解释观察到的浓度与当前速度之间的相位关系。
[1] In shelf and coastal waters, point measurements of fine suspended sediment concentrations commonly display phase and frequency differences with respect to local current forcing. Phase shifts are often attributed to tidal advection and slow-settling velocities of cohesive sediments. The phase relationship between tidal current speeds and near-bed mud concentrations obtained at a site off the east coast of England is investigated. A simple depth-averaged advection-diffusion model is introduced and used to explore the influence of relative changes in settling, advection, and local erosion on the temporal evolution of suspension events. The model includes two source terms: local resuspension in phase with current speed and advection of a horizontal gradient in phase with tidal displacement. Incorporating a settling (or sink) term introduces a negative or positive phase shift in the advection or resuspension term, respectively. The settling term accounts for the vertical structure of suspension and becomes important at slack water when the near-bed concentration, and thus deposition, rapidly increases. Model results are compared with suspended mud concentration data to help explain the observed phase relationships between concentration and current speed.