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Ocean ventilation is the process by which climatically important tracers such as heat and carbon are exchanged between the atmosphere and ocean interior. In this paper a series of numerical simulations are used to study the interaction of submesoscales and a topographically steered jet in driving rapid ventilation. The ventilation is found to increase both as a function of wind stress and model resolution, with a submesoscale-resolving 1/1208 model exhibiting the largest ventilation rate. The jet in this simulation is found to be persistently unstable to submesoscale instabilities, which are known to feature intense vertical circulations. The vertical tracer transport is found to scale as a function of the eddy kinetic energy and mean isopycnal slope, whose behaviors change as a function of the wind stress and due to the emergence of a strong potential vorticity gradient due to the lateral shear of the jet. These results highlight the importance of jet- submesoscale interaction as a bridge between the atmosphere and the ocean interior. [ABSTRACT FROM AUTHOR]

Tides and tidally generated waves play a key role in modulating the heat budget of the nearshore environment, which can significantly affect the ecology of the coastal and reef zones. The high spatial resolution required to resolve such waves in numerical models means that diagnosing wave-generated heat fluxes (WHFs) has so far only been possible over very limited areas. Because many marine ecosystems that are affected by WHFs, such as coral reefs, are patchily distributed within domains of hundreds of kilometers, an alternative to fully wave-resolving models is needed to identify thermal refugia and guide conservation efforts over larger regions. In this study, a one-way nested series of regional ocean simulations has been conducted to study the role of waves in driving high-frequency temperature variations in the Coral Triangle and to develop a method for identifyingWHFin coarser-resolution models. Afiltering method using Lagrangian particles is used to separate the wave component of the flow, which is used to diagnose the wave energy and to identify locations experiencing large, high-frequency temperature variability. These locations are shown to possess three key characteristics: large time-mean wave kinetic energy, shallow depth, and a steep bathymetric gradient that gives access to a nearby source of cold, subthermocline water. A function of the wave kinetic energy and bathymetric slope is found to closely correlate with areas of maximal temperature variance, suggesting its use as a convenient and readily calculable metric to locate thermal refugia in observations or numerical experiments over large spatial domains. [ABSTRACT FROM AUTHOR]

The Gent and McWilliams (1990, GM) tracer transport scheme has long been a cornerstone of global-scale ocean modeling, and is well-known for its ability to mimic the effects of baroclinic turbulence by reducing the available potential energy of resolved flows. However, theory predicts that baroclinic turbulence also acts to transfer this potential energy to kinetic energy, which can then be fluxed toward larger scales by an inverse energy cascade. These dynamical processes represent a separate branch of the large-scale ocean energy cycle which GM presently does not account for. In this paper a framework is developed which allows the potential energy removed by the GM scheme to be transferred to resolved motions. In this framework, which is labeled GM+E (or "GM plus energetics"), the energy transfer occurs by employing GM alongside a parameterization of the barotropic Reynolds stresses in the momentum equations, which takes the form of a negative harmonic viscosity acting on the barotropic velocities. The Reynolds stress parameterization is considered as being complementary to GM, in that its energetics are explicitly tied to those of GM while being independent of the choice of transfer coefficient or form of the GM closure. A set of idealized baroclinic spindown simulations is used to compare GM+E against standard GM, and is shown to substantially improve the kinetic energy spectra, probability distributions of flow structures, and restratification rate within the front relative to an eddy-resolving truth simulation. • Mesoscale eddy closures should convert PE to KE, which is then cascaded upscale. • The energy extracted by the GM parameterization currently disappears from the model. • A closure for the barotropic Reynolds stresses is developed to complement GM. • "GM+E", the combined Reynolds stress and GM, closes the large scale energy cycle. • KE spectra and flow structures are improved by GM+E compared to standard GM. [ABSTRACT FROM AUTHOR]