TY - JOUR

T1 - Tidal conversion and mixing poleward of the critical latitude (an Arctic case study)

AU - Rippeth, Thomas

AU - Vlasenko, Vasiliy

AU - Stashchuk, Nataliya

AU - Scannell, Brian

AU - Green, Mattias

AU - Lincoln, Benjamin

AU - Bacon, Sheldon

PY - 2017/12/28

Y1 - 2017/12/28

N2 - The tides are a major source of the kinetic energy supporting turbulent mixing in the global oceans. The prime mechanism for the transfer of tidal energy to turbulent mixing results from the interaction between topography and stratified tidal flow, leading to the generation of freely propagating internal waves at the period of the forcing tide. However, poleward of the critical latitude (where the period of the principal tidal constituent exceeds the local inertial period), the action of the Coriolis force precludes the development of freely propagating linear internal tides. Here we focus on a region of sloping topography, poleward of the critical latitude, where there is significant conversion of tidal energy and the flow is supercritical (Froude number, Fr > 1). A high-resolution non-linear modelling study demonstrates the key role of tidally generated lee waves and super-critical flow in the transfer of energy from the barotropic tide to internal waves in these high latitude regions. Time series of flow and water column structure from the region of interest show internal waves with characteristics consistent with those predicted by the model, and concurrent microstructure dissipation measurements show significant levels of mixing associated with these internal waves. The results suggest that tidally generated lee-waves are a key mechanism for the transfer of energy from the tide to turbulence poleward of the critical latitude

AB - The tides are a major source of the kinetic energy supporting turbulent mixing in the global oceans. The prime mechanism for the transfer of tidal energy to turbulent mixing results from the interaction between topography and stratified tidal flow, leading to the generation of freely propagating internal waves at the period of the forcing tide. However, poleward of the critical latitude (where the period of the principal tidal constituent exceeds the local inertial period), the action of the Coriolis force precludes the development of freely propagating linear internal tides. Here we focus on a region of sloping topography, poleward of the critical latitude, where there is significant conversion of tidal energy and the flow is supercritical (Froude number, Fr > 1). A high-resolution non-linear modelling study demonstrates the key role of tidally generated lee waves and super-critical flow in the transfer of energy from the barotropic tide to internal waves in these high latitude regions. Time series of flow and water column structure from the region of interest show internal waves with characteristics consistent with those predicted by the model, and concurrent microstructure dissipation measurements show significant levels of mixing associated with these internal waves. The results suggest that tidally generated lee-waves are a key mechanism for the transfer of energy from the tide to turbulence poleward of the critical latitude

KW - OCEANOGRAPHY

KW - Tides

KW - mixing

KW - Arctic

U2 - 10.1002/2017GL075310

DO - 10.1002/2017GL075310

M3 - Article

VL - 44

SP - 12349

EP - 12357

JO - Geophysical Research Letters

JF - Geophysical Research Letters

SN - 0094-8276

IS - 24

ER -