The structure and stability of mode-2 internal solitary-like waves is investigated experimentally. A rank-ordered train of mode-2 internal solitary waves is generated using a lock release configuration. The pycnocline is centred either on the mid-depth of the water column (the 0% offset case) or it is offset in the positive vertical direction by a fraction of 5%, 10% or 20% of the total fluid depth. It is found that offsetting the pycnocline has little effect on the basic wave properties (e.g wave speed, wave amplitude and wave length) but it does significantly affect wave stability. Instability takes the form of small K-H-like billows in the rear of the wave and small scale overturning in the core of the wave. In the 0% offset case, instability occurs on both the upper and lower interfaces of the pycnocline and is similar in extent and vigour over the two interfaces. As the offset percentage is increased, however, instability is more pronounced on the lower interface with little or no evidence of instability being observed on the upper interface. In the 20% offset case a mode-1 tail is associated with the wave and the wave characteristics resemble qualitatively the recent field observations of Shroyer et al [E. L. Shroyer, J. N. Moum and J. D. Nash, J. Geophys. Res. 115, C07001 (2010)].
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机译：实验研究了模式2内部孤波的结构和稳定性。使用锁定释放配置生成模式2内部孤立波的按顺序排列的序列。碧萝oc的中心位于水柱的中间深度（偏移量为0％的情况下），或者在正垂直方向上偏移总流体深度的5％，10％或20％。已经发现，抵消比考克林对基本波特性（例如波速，波幅和波长）的影响很小，但确实会显着影响波的稳定性。不稳定表现为波浪后部有类似K-H的小波浪，而波浪中心有小规模的倾覆。在0％偏移量的情况下，不稳定性在比考克林的上下界面上均发生，并且在两个界面上的范围和活力相似。但是，随着偏移百分比的增加，在下部界面上的不稳定性更加明显，在上部界面上几乎没有或没有观察到不稳定性的迹象。在20％偏移的情况下，模式1的尾部与波相关联，并且波的特性在质量上与Shroyer等人[E. L. Shroyer，J。N. Moum和J. D. Nash，J。Geophys。 Res。 115，C07001（2010）]。
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