Internal tide cycle and topographic scattering over the North Mid-Atlantic Ridge
Résumé
Internal tides are a predominant source of high-frequency variability and diapycnal mixing in the ocean. Understanding their dynamics and lifecycle is necessary to better understand their role in the ocean circulation. In this paper, we describe and quantify internal tide generation, propagation and dissipation in a sector of the North Mid-Atlantic Ridge, using high-resolution numerical simulations with realistic bathymetry and stratification. We show that the generation and dissipation of internal tides, as well as the distribution of internal tides amongst vertical modes, exhibit high spatial variability. We find that topographic scattering leads to a significant transfer of energy towards high vertical modes and thereby enhances internal tide dissipation. On average, and especially on the ridge, this mechanism is dominant over the conversion from the barotropic tide for transferring energy to high (>7) vertical modes. The magnitude of the scattering of the first baroclinic internal mode is found to be in good agreement with theoretical predictions. [doi: 10.1029/2020JC016376]
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