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Stratification Anomalies in the Ocean Interior
  • +3
  • Bailey Avila,
  • Miles Sundermeyer,
  • Marie-Pascale Lelong,
  • Eric Kunze,
  • Jeffrey Early,
  • Cimarron Wortham
Bailey Avila
University of Massachusetts - Dartmouth

Corresponding Author:bavila2@umassd.edu

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Miles Sundermeyer
School Marine Sci. & Tech.
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Marie-Pascale Lelong
NorthWest Research Associates
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Eric Kunze
U of Washington, Seattle, WA
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Jeffrey Early
NorthWest Research Associates
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Cimarron Wortham
University of Washington
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Abstract

Internal waves and vortical mode are ubiquitous in the ocean, providing a conduit for energy transfer from tides and wind-driven circulation to fine- and micro-scale turbulence associated with internal-wave breaking and dissipation. Numerical simulations of a Garrett-Munk internal-wave field are used to study the interactions between internal waves and vortical mode, and the generation of turbulent mixing events and semi-permanent finestructure (vortical mode). Regions of reduced stratification are found to occupy between ~5% and 25% of the model domain, depending on the strength of the anomalies. Decomposition of 3-dimensional model fields into linear internal-wave and vortical-mode components shows that both influence stratification, with ~88% of the anomalies due to linear internal waves and ~40% due to vortical mode, the overlap in percentiles representing regions that are a combination of the two. The time evolution of anomalies is examined, from the initial generation to eventual dissipation. Results further describe the preconditions of these regions, including their relation to a subcritical Richardson number and overturning / mixing events as quantified via Thorpe scales and turbulent dissipation rate.