Tidally Induced Turbulence in the Abyssal Ocean

Fuente: arXiv
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Auteurs principaux: Si, Yidongfang, Ferrari, Raffaele, Voet, Gunnar
Format: Preprint
Publié: 2025
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author Si, Yidongfang
Ferrari, Raffaele
Voet, Gunnar
author_facet Si, Yidongfang
Ferrari, Raffaele
Voet, Gunnar
contents It has been suggested that the upwelling branch of the abyssal overturning circulation is characterized by strong flows driven by turbulence along sloping topography. The Boundary Layer Turbulence field campaign has provided direct evidence for strong upslope flows along a deep submarine canyon of the Rockall Trough. Turbulent overturning events spanning 200 m in the vertical were observed every tidal cycle, suggesting that the strong tidal flows in the canyon periodically undergo some form of instability. However, it is shown that the flow never satisfied the classical instability condition for time-independent sheared flows in a stratified fluid commonly used in oceanographic studies to determine transition to turbulence. This study illustrates that the time dependence of the tidal flow changes the stability properties and explains the observed transition to a turbulent state. The findings suggest that turbulent mixing induced by oscillatory shear flow may be ubiquitous over sloping topography and play an important role in deep ocean mixing that supports the global overturning circulation.
format Preprint
id arxiv_https___arxiv_org_abs_2509_05869
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Tidally Induced Turbulence in the Abyssal Ocean
Si, Yidongfang
Ferrari, Raffaele
Voet, Gunnar
Atmospheric and Oceanic Physics
Fluid Dynamics
It has been suggested that the upwelling branch of the abyssal overturning circulation is characterized by strong flows driven by turbulence along sloping topography. The Boundary Layer Turbulence field campaign has provided direct evidence for strong upslope flows along a deep submarine canyon of the Rockall Trough. Turbulent overturning events spanning 200 m in the vertical were observed every tidal cycle, suggesting that the strong tidal flows in the canyon periodically undergo some form of instability. However, it is shown that the flow never satisfied the classical instability condition for time-independent sheared flows in a stratified fluid commonly used in oceanographic studies to determine transition to turbulence. This study illustrates that the time dependence of the tidal flow changes the stability properties and explains the observed transition to a turbulent state. The findings suggest that turbulent mixing induced by oscillatory shear flow may be ubiquitous over sloping topography and play an important role in deep ocean mixing that supports the global overturning circulation.
title Tidally Induced Turbulence in the Abyssal Ocean
topic Atmospheric and Oceanic Physics
Fluid Dynamics
url https://arxiv.org/abs/2509.05869