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Turbulent diffusivity profiles on the shelf and slope at the southern edge of the Canada Basin
  • +3
  • Ruby M Yee,
  • Ruth Musgrave,
  • Elizabeth Fine,
  • Jonathan Nash,
  • Louis St. Laurent,
  • Robert Pickart
Ruby M Yee
Department of Oceanography, Dalhousie University

Corresponding Author:[email protected]

Author Profile
Ruth Musgrave
Woods Hole Oceanographic Institute, Department of Oceanography, Dalhousie University
Elizabeth Fine
Scripps Institution of Oceanography
Jonathan Nash
Oregon State University College of Earth, Ocean, and Atmospheric Sciences
Louis St. Laurent
University of Washington Applied Physics Laboratory
Robert Pickart
Woods Hole Oceanographic Institute

Abstract

    Vertical profiles of temperature microstructure at 95 stations were obtained over the Beaufort shelf and shelfbreak in the southern Canada Basin during a November 2018 research cruise. Two methods for estimating the dissipation rates of temperature variance and turbulent kinetic energy were compared using this dataset. Both methods require fitting a theoretical spectrum to observed temperature gradient spectra, but differ in their assumptions. The two methods agree for calculations of the dissipation rate of temperature variance, but not for that of turbulent kinetic energy. After applying a rigorous data rejection framework, estimates of turbulent diffusivity and heat flux are made across different depth ranges. The turbulent diffusivity of temperature is typically enhanced by about one order of magnitude in profiles on the shelf compared to near the shelfbreak, and similarly near the shelfbreak compared to profiles with bottom depth >1000 m. Depth bin means are shown to vary depending on the averaging method (geometric means tend to be smaller than arithmetic means and maximum likelihood estimates). The statistical distributions of heat flux within the surface, cold halocline, and Atlantic water layer change with depth. Heat fluxes are typically <1 Wm−2, but are greater than 50 Wm−2 in ∼8% of the overall data. These largest fluxes are located almost exclusively within the surface layer, where temperature gradients can be large.
07 Feb 2024Submitted to ESS Open Archive
08 Feb 2024Published in ESS Open Archive