Current shear and turbulence during a near-inertial wave

Frontiers in Marine Science

Marine Science

Göran Broström¹  Graig Sutherland²  Johannes Röhrs³  Lars Robert Hole³  Knut-Frode Dagestad³  Trygve Halsne⁴  Kai H. Christensen⁵ 

[1] Department of Marine Sciences, University of Gothenburg, Gothenburg, Sweden;Environmental Numerical Prediction Research, Environment and Climate Change Canada, Dorval, QC, Canada;Norwegian Meteorological Institute, Oslo, Norway;Norwegian Meteorological Institute, Oslo, Norway;Geophysical Institute, University of Bergen, Bergen, Norway;Norwegian Meteorological Institute, Oslo, Norway;Institute for Geoscience, University of Oslo, Oslo, Norway;

关键词: near-inertial wave;    surface current;    turbulence;    dissipation;    ADCP;    drifter trajectory;   

DOI  :  10.3389/fmars.2023.1115986

 received in 2022-12-04, accepted in 2023-03-22,  发布年份 2023

来源: Frontiers

【 摘 要 】

Surface currents and turbulent mixing were observed during a near-inertial wave (NIW) using an accousting doppler current profiler (ADCP) and satellite-tracked drifters. Drifter trajectories sampled at three depth levels show characteristics of an Ekman solution superposed with the NIW. Velocity and dissipation estimates from the ADCP reveal strong shear with a distinct constant flux layer in between the roughness length and a critical depth at 4m. Below, a shear free slab layer performing an inertial oscillation is observed. Dissipation, as estimated from the vertical beam of the ADCP, peaks in the wave-enhanced friction layer when the current opposes the wind and wave direction. Below the constant flux layer, maximum turbulence is observed when the NIW is in a phase that is in opposite direction to the time-averaged current. During this phase, currents at various depths rapidly realign in the entire boundary layer.

【 授权许可】

Unknown   
Copyright © 2023 Röhrs, Halsne, Sutherland, Dagestad, Hole, Broström and Christensen