A downslope propagating thermal front over the continental slope
A downslope propagating thermal front over the continental slope
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DOI：
10.1002/2017jc012797
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发表时间：
2017-04
影响因子：
--
通讯作者：
H. Haren;P. Hosegood
中科院分区：
文献类型：
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作者：
H. Haren;P. Hosegood
在海洋中，倾斜地形上的内部锋面孔有多种形态，这取决于局部密度分层以及载波的产生角度和来源。但它们的共同特征是后向破碎波，强烈的沉积物再悬浮，以及相对较冷(密度较大)的水在温暖(不太密度)的水下或多或少向上移动。在本文中，我们给出了一个罕见的下坡冷水锋在近底部暖水上移动的例子。在下坡移动锋的后缘观察到较大的后向散射，而不是在上坡移动锋中常见的前缘。时间序列观测是在夏季的两个星期内进行的，使用了101米长的高分辨率温度传感器阵列，与无声多普勒海流剖面仪一起停泊在396米深的近乎均匀的水域中，靠近马林陆架(英国西苏格兰)陆坡上的一个小峡谷。发生在具有潮汐周期的上坡锋面之间，罕见的下坡传播类似于重力流，包括来自内陆的强对流湍流，而不是更常见的由与海床相互作用而产生的摩擦产生的湍流。它的湍流比更常见的上坡传播锋面大3-10倍。由于主要的湍流是在内陆，靠近底部有一个薄的层状层，所以很少的泥沙被下坡传播锋面重新悬浮。认为下坡传播锋是由内波(潮汐)的斜向传播和绕过上游附近的海角形成的。
In the ocean, internal frontal bores above sloping topography have many appearances,depending on the local density stratification, and on the angle and source of generation of the carrier wave.However, their common characteristics are a backward breaking wave, strong sediment resuspension, andrelatively cool (denser) water moving more or less upslope underneath warm (less dense) water. In thispaper, we present a rare example of a downslope moving front of cold water moving over near-bottomwarm water. Large backscatter is observed in the downslope moving front’s trailing edge, rather than theleading edge as is common in upslope moving fronts. Time series observations have been made during afortnight in summer, using a 101 m long array of high-resolution temperature sensors moored with anacoustic Doppler current profiler at 396 m depth in near-homogeneous waters, near a small canyon in thecontinental slope off the Malin shelf (West-Scotland, UK). Occurring between fronts that propagate upslopewith tidal periodicity, the rare downslope propagating one resembles a gravity current and includes strongconvective turbulence coming from the interior rather than the more usual frictionally generated turbulencearising from interaction with the seabed. Its turbulence is 3–10 times larger than that of more commonupslope propagating fronts. As the main turbulence is in the interior with a thin stratified layer close tothe bottom, little sediment is resuspended by a downslope propagating front. The downslope propagatingfront is suggested to be generated by oblique propagation of internal (tidal) waves and flow over a nearbyupstream promontory.