Topographically induced internal solitary waves in a pycnocline: Ultrasonic probes and stereo-correlation measurements
Topographically induced internal solitary waves in a pycnocline: Ultrasonic probes and stereo-correlation measurements
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密斜层中地形诱发的内部孤立波：超声波探头和立体相关测量
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
E. Cid
中科院分区：
文献类型：
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作者：
Y. Dossmann;A. Paci;F. Auclair;Mathieu Lepilliez;E. Cid
内孤立波(ISW)是在海洋跃层等密度梯度较高的区域传播的大振幅稳定波。人们经常用二维的方法来研究它们的动力学，然而，它们的三维演化仍然鲜为人知。在CNRM-GAME的大型分层水箱中进行了实验，以研究受海洋体制启发的两种学术构型中ISW的产生。首先，用超声波探头测量了两种构型的界面位移。在初始两层密度不变的情况下，通过两组不同振幅和强迫频率的实验研究了孤立面波的产生。在下层分层的二次生成情况下，研究了内波波束对跃层的影响产生的ISW及其后续的动力学。在这两种情况下，ISW的动力学特性与类似构型下的解析方法和数值模拟结果符合得很好。然后，利用立体相关技术的最新进展来描述传播的ISW的三维结构。在初级结构中，在ISW传播过程中观察到了小的横向效应。在第二代构型中，界面波动力学中观察到较大的横向结构。界面槽与低层内波之间的相互作用可能是产生这些结构的原因。在这两种构型中，这些横向结构的大小是用无量纲参数来量化的。它们在第二代情况下是在第一代情况下的两倍。
Internal solitary waves (ISWs) are large amplitude stable waves propagating in regions of high density gradients such as the ocean pycnocline. Their dynamics has often been investigated in two-dimensional approaches, however, their three-dimensional evolution is still poorly known. Experiments have been conducted in the large stratified water tank of CNRM-GAME to study the generation of ISWs in two academic configurations inspired by oceanic regimes. First, ultrasonic probes are used to measure the interfacial displacement in the two configurations. In the primary generation case for which the two layers are of constant density, the generation of ISWs is investigated in two series of experiments with varying amplitude and forcing frequency. In the secondary generation case for which the lower layer is stratified, the generation of ISWs from the impact of an internal wave beam on the pycnocline and their subsequent dynamics is studied. The dynamics of ISWs in these two regimes accords well with analytical approaches and numerical simulations performed in analogous configurations. Then, recent developments of a stereo correlation technique are used to describe the three-dimensional structure of propagating ISWs. In the primary generation configuration, small transverse effects are observed in the course of the ISW propagation. In the secondary generation configuration, larger transverse structures are observed in the interfacial waves dynamics. The interaction between interfacial troughs and internal waves propagating in the lower stratified layer are a possible cause for the generation of these structures. The magnitude of these transverse structures is quantified with a nondimensional parameter in the two configurations. They are twice as large in the secondary generation case as in the primary generation case.