Radiation and Dissipation of Internal Waves Generated by Geostrophic Motions Impinging on Small-Scale Topography: Theory

By M. Nikurashin, Raffaele Ferrari. 2010

205 citations recorded by the source corpus.

Abstract Observations and inverse models suggest that small-scale turbulent mixing is enhanced in the Southern Ocean in regions above rough topography. The enhancement extends O(1) km above the topography, suggesting that mixing is supported by the breaking of gravity waves radiated from the ocean bottom. In this study, it is shown that the observed mixing rates can be sustained by internal waves generated by geostrophic motions flowing over bottom topography. Weakly nonlinear theory is used to describe the internal wave generation and the feedback of the waves on the zonally averaged flow. Vigorous inertial oscillations are driven at the ocean bottom by waves generated at steep topography. The wave radiation and dissipation at equilibrium is therefore the result of both geostrophic flow and inertial oscillations differing substantially from the classical lee-wave problem. The theoretical predictions are tested versus two-dimensional high-resolution numerical simulations with parameters representative of ...

Subfields: Atmospheric Science, Oceanography

View Paper: https://www.semanticscholar.org/paper/30128d94fc98c08e17fb4fc6a54121c1743dce57

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Citations in the corpus

Submesoscale currents in the ocean (2016, background): “One is the current-induced generation of lee IGWs radiating away from the slope and perhaps overturning (breaking) and mixing locally if steep enough [52].”
Overturning circulation driven by breaking internal waves in the deep ocean (2013, methodology): “…mixing locally, from the 30% value used by St. Laurent et al. [2002] to 50%, a value suggested by idealized numerical simulations for lee waves [Nikurashin and Ferrari, 2010a; Nikurashin and Ferrari, 2010b], increases the maximum of the water-mass transformation driven by lee wave-driven…”
A Framework for Parameterizing Eddy Potential Vorticity Fluxes (2012, background): “2008), loss of energy to internal waves (e.g., Molemaker et al. 2005; Polzin 2008; Marshall and Naveira Garabato 2008; Nikurashin and Ferrari 2010), western boundary dissipation (e.”
Radiation and Dissipation of Internal Waves Generated by Geostrophic Motions Impinging on Small-Scale Topography: Application to the Southern Ocean (2010, methodology): “…along each section for the two regions considered. a. Steepness parameter estimate Idealized numerical simulations with monochromatic topography (Nikurashin and Ferrari 2010) show that the characteristics and magnitude of the radiated waves are controlled by the steepness parameter, 0, defined…”
Global energy conversion rate from geostrophic flows into internal lee waves in the deep ocean (2011, background): “, 2010], and through internal wave generation at rough topography [Nikurashin and Ferrari, 2010a]. Sen et al. [2008] estimate that 0.2–0.8 TW of the wind power input into geostrophic flows dissipates in the bottom boundary layer by quadratic bottom drag. Zhai et al. [2010] speculate that western bou”
Significant sink of ocean-eddy energy near western boundaries (2010, background): “A fraction of the eddy energy in the Southern Ocean may be transferred to internal lee waves and oscillations over rough bottom topography, leading to bottom-enhanced diapycnal mixin”
Spatial and temporal variability of global ocean mixing inferred from Argo profiles (2012, background): “…interacting with the high concentration of eddies [Padman et al., 1990; Kunze, 1995], internal waves generated from topographyeddy interactions [Nikurashin and Ferrari, 2010; Liang and 5 of 6 Thurnherr, 2012], or due to incorrectly identifying the strain associated with the eddies as internal…”