Abstract In this paper, the shoaling mode-2 internal solitary waves (ISWs) in the Pacific coast of Central America are studied for the first time using seismic oceanography method. It is found that there is an asymmetry in the vertical amplitude variation of the mode-2 ISWs front and rear during the shoaling process. The amplitude may weaken the effect of the pycnocline deviation on the stability of the mode-2 ISWs. For large amplitudes, the pycnocline needs to deviate greatly, so that the mode-2 ISWs become unstable; for small amplitude, the pycnocline deviates very little, and the mode-2 ISWs become unstable. The pre-stack migration sections of the common offset gathers are used to calculate the apparent phase velocities of the mode-2 ISWs. It is found that in deep water, the seafloor depths and amplitudes simultaneously control the magnitude of the apparent phase velocities of the mode-2 ISWs; in shallow water, the amplitudes mainly controls the magnitude of the apparent phase velocities of the mode-2 ISWs. For the mode-2 ISWs with small amplitudes ( 2 a / h 2 ≤ 2 ) in shallow water, the apparent phase velocities increase with the amplitudes, and increase rapidly; for the mode-2 ISWs with large amplitudes ( 2 a / h 2 > 2 ) in shallow water, the apparent phase velocities increase with the amplitudes, but increase slowly. By calculating the relative seismic spectrum energy, it is found that the seismic spectrum energy in the submesoscale wavenumber range corresponds well to the mode-2 ISWs waveform. The mode-2 ISWs in the shoaling process have submesoscale characteristics.

中文翻译：

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海洋地震勘测资料研究中美洲太平洋沿岸浅滩模式2内部孤立波

摘要 本文首次采用地震海洋学方法研究了中美洲太平洋沿岸浅滩模式2内部孤立波(ISWs)。发现在浅滩化过程中，模式2 ISWs前后的垂直幅度变化存在不对称性。振幅可能会减弱pycnocline偏差对模式2 ISWs稳定性的影响。对于大的振幅，pycnocline 需要有很大的偏离，使得模式 2 的 ISW 变得不稳定；对于小振幅，pycnocline 偏差很小，并且模式 2 ISW 变得不稳定。共同偏移道集的叠前偏移剖面用于计算模式2 ISW 的视相速度。发现在深水中，海底深度和振幅同时控制模式 2 ISW 的视相速度的大小；在浅水中，振幅主要控制模式 2 ISW 的视相速度的大小。对于浅水中幅度较小（2 a / h 2 ≤ 2 ）的模式2 ISW，视相速度随幅度增加而迅速增加；对于浅水中幅度较大（2 a / h 2 > 2 ）的模式2 ISW，视相速度随幅度增加而增加，但增加缓慢。通过计算相对地震谱能量，发现亚中尺度波数范围内的地震谱能量与模态2 ISWs波形对应较好。浅滩化过程中的模式 2 ISW 具有亚中尺度特征。