Abstract

The structure and characteristics of the internal wave field (coherence, frequency spectra, phase velocities, dispersion of velocity fluctuations) observed in an ocean frontal zone on the shelf-slope east of the island of Malta is studied. Using spectral and coherence analysis of temporal temperature variations measured by two thermistor chains 7 km apart the near-inertial internal gravity waves (NIWs) were detected, and their wavelengths and trace velocities were estimated. The temperature, salinity and density front that existed during the measurement period and the bottom irregularities of island’s shelf are both proposed to be the sources of the observed NIWs and internal waves of different periods. The mechanism of formation of the frequency spectrum of the observed internal wave field is proposed. By analyzing the effect of advection of internal waves by an alternating current induced by all the internal waves the observed periodic change of the sign of the trace velocity of the internal waves is explained.

中文翻译：

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地中海马耳他以东洋锋区内波场结构与特征

摘要

研究了在马耳他岛东部陆架斜坡上的海洋锋区观测到的内波场的结构和特征（相干性、频谱、相速度、速度波动的离散度）。使用相距 7 公里的两个热敏电阻链测量的时间温度变化的光谱和相干性分析，检测到近惯性内部重力波 (NIW)，并估计它们的波长和迹速度。测量期间存在的温度、盐度和密度锋以及岛架底部不平整度均被认为是不同时期观测到的NIW和内波的来源。提出了观测到的内波场频谱的形成机制。通过分析所有内波感应的交变电流对内波平流的影响，解释了观察到的内波迹速度符号的周期性变化。