Tidally-forced lee waves drive turbulent mixing along the Arctic Ocean margins

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  • Ilker Fer
    University of BergenBjerknes Centre for Climate Research
  • Zoe Koenig
    University of BergenBjerknes Centre for Climate Research
  • Igor Koslov
    Russian State Hydrometeorological University Saint-Petersburg
  • Marek Ostrowski
    Institute of Marine Sciences, Bergen
  • Tom Rippeth
  • Laurie Padman
    Earth & Space Research
  • Anthony Bosse
    University of BergenBjerknes Centre for Climate Research
  • Eivind Kolas
    University of BergenBjerknes Centre for Climate Research
In the Arctic Ocean, limited measurements indicate that the strongest mixing below the atmospherically forced surface mixed layer occurs where tidal currents are strong. However, mechanisms of energy conversion from tides to turbulence, and the overall contribution of tide-driven mixing to Arctic Ocean state, are poorly understood. We present measurements from the shelf north of Svalbard that show abrupt isopycnal vertical displacements of 10{50} m and intense dissipation associated with cross-isobath diurnal tidal currents of ~ 0:15 m/s. Energy from the barotropic tide accumulated in a trapped baroclinic lee wave during maximum downslope flow , which and was released around slack water. During a 6-h turbulent event, high frequency internal waves were present, the full 300 m depth water column became turbulent, dissipation rates increased by a factor of 100 and turbulent heat flux averaged 15 W/m2 compared with the background rate of 1 W/m2.

Keywords

  • Svalbard, dissipation rate, Arctic Ocean, ocean microstructure, nonlinear waves, critical flow
Original languageEnglish
Article number2020GL088083R
JournalGeophysical Research Letters
Volume47
Issue number16
Early online date6 Aug 2020
DOIs
Publication statusPublished - 28 Aug 2020
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