Estimating Meridional Energy Fluxes by Internal Waves in the Southern Ocean Using a High‐Resolution Simulation

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Abstract
Using a 1/48 global MITgcm simulation, this study quantifies meridional internal wave energy fluxes in the Southern Ocean across 35S, 45S, 55S, and 65S from 29 May to 15 November 2012. Fluxes are separated into three bands: semidiurnal, near‐inertial, and continuum. Zonally integrated total fluxes are poleward at O(10) GW (15.3, 7.0, and 15.9 GW across 35S, 45S, and 55S, respectively), dropping to 0.3 GW at 65S. The semidiurnal tidal band accounts for over 80% of the total flux, contributing 13.4, 5.7, and 14.8 GW at 35–55S, before dropping to 0.15 GW at 65S. This sharp decrease represents a convergence of ∼15 GW between 55S and 65S, corresponding to a background diapycnal diffusivity of . Equatorward semidiurnal fluxes are spatially intermittent and limited to a few topographic features, including the Macquarie Ridge and mid‐ocean ridges. In contrast, poleward fluxes are more broadly distributed in the Pacific but dominated by a few major hotspots in the Atlantic and Indian sectors, most notably the Drake Passage. Continuum band fluxes decrease from 2.3 GW at 35S to 0.2 GW at 65S, with a consistent approximately 0.7 GW convergence across each 10 latitude band. In the near‐inertial band, from 35S to 55S, zonally integrated flux accounts for just 1%–3% of the total internal wave flux and is mostly equatorward, acting against the net flux. Despite 17.4 GW of near‐inertial wind work between 35S and 65S, the meridional flux divergence remains weak, exporting only 1%–4% of the wind input.

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