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Near-inertial waves and turbulence driven by the growth of swell
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  • Gregory Wagner,
  • Greg Chini,
  • Ali Ramadhan,
  • Basile Gallet,
  • Raffaele Ferrari
Gregory Wagner
Massachusetts Institute of Technology

Corresponding Author:[email protected]

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Greg Chini
University of New Hampshire
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Ali Ramadhan
Massachusetts Institute of Technology
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Basile Gallet
Commissariat á l'Energie Atomique Saclay
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Raffaele Ferrari
Massachusetts Institute of Technology
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Between 5 and 25% of the total momentum transferred between the atmosphere and ocean is transmitted via the growth of long surface gravity waves called ‘swell’. In this paper, we use large eddy simulations to show that swell-transmitted momentum excites near-inertial waves and drives turbulent mixing that deepens a rotating, stratified, turbulent ocean surface boundary layer. We find that swell-transmitted currents are less effective at producing turbulence and mixing the boundary layer than currents driven by an effective surface stress. Overall, however, the differences between swell-driven and surface-stress-driven boundary layers are relatively minor. In consequence, our results corroborate assumptions made in Earth system models that neglect the vertical structure of swell-transmitted momentum fluxes and instead parameterize all air-sea momentum transfer processes with an effective surface stress.
May 2021Published in Journal of Physical Oceanography volume 51 issue 5 on pages 1337-1351. 10.1175/JPO-D-20-0178.1