Forward flux and enhanced dissipation of geostrophic balanced energy

Thomas, Jim; Daniel, Don

doi:10.1017/jfm.2020.1026

Cited by 18 publications

(22 citation statements)

References 48 publications

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“…This cascade‐modifying process was termed stimulated cascade in Barkan et al. (2017), and was since discussed in Xie (2020) and J. Thomas and Daniel (2021).…”

Section: Cross‐scale Energy Transfersmentioning

confidence: 99%

Oceanic Mesoscale Eddy Depletion Catalyzed by Internal Waves

Barkan

Srinivasan

Yang

et al. 2021

Geophysical Research Letters

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The general circulation of the ocean is strongly constrained by the pathways that kinetic and available potential energy take from the basin-scale forces that inject them to centimeter scales, where they are depleted. To determine the ocean's response to future climate scenarios, these energy pathways, from forcing to dissipation, must be understood and quantified.Mesoscale eddies, with horizontal scales on the order of 100 km and timescales longer than many days, are well known as the dominant reservoir of kinetic energy (KE) in the oceans (Wunsch & Ferrari, 2004). But because their dynamics are constrained by an approximate geostrophic and hydrostatic force balance, they are characterized by an inverse KE cascade, and by themselves do not provide the necessary forward scale-transfer to dissipation (Müller et al., 2005). Possible mechanisms to interrupt the mesoscale inverse cascade include interaction with the bottom topography and boundary layer (

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“…This cascade‐modifying process was termed stimulated cascade in Barkan et al. (2017), and was since discussed in Xie (2020) and J. Thomas and Daniel (2021).…”

Section: Cross‐scale Energy Transfersmentioning

confidence: 99%

Oceanic Mesoscale Eddy Depletion Catalyzed by Internal Waves

Barkan

Srinivasan

Yang

et al. 2021

Geophysical Research Letters

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“…We conclude this section by pointing out that the transition in flow dynamics, that is, the features of the barotropic flow changing from QG to SW regime as seen in the top row of Figure 2, was consistently observed in the three-dimensional studies of Thomas and Daniel (2020) and Thomas and Daniel (2021). The non-divergent barotropic flow therefore forms the simplest two-dimensional flow that transitions in its dynamic features based on the wave energy level.…”

Section: 𝑇𝑇mentioning

confidence: 58%

“…Over the past one decade a wide range of datasets, including in situ oceanic observations and high resolution global scale ocean model outputs, indicate increased levels of gravity wave energy on transitioning from mesoscales to submesoscales in the world's oceans. Investigations, using three‐dimensional Boussinesq equations and reduced two‐dimensional models, reveal breaking up of coherent vortices and formation of energetic small‐scale dynamics in wave‐dominated turbulent regimes (TY, Thomas & Arun, 2020; Thomas & Daniel, 2020, 2021). Although the specific energy transfer details depend on the kind of wave field, turbulent dynamics of wave‐dominated regimes are in general significantly different from quasi‐geostrophic regimes, the latter consisting of well‐defined large‐scale coherent vortices.…”

Section: Summary and Discussionmentioning

confidence: 99%

Wave‐Enhanced Tracer Dispersion

Thomas

Gupta

2022

JGR Oceans

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Recent oceanic datasets indicate high gravity wave‐to‐balance energy ratio at submesoscales. Idealized investigations exploring such wave‐dominated regimes have found that waves can break up coherent vortices and generate energetic small scale flow structures, indicating that the turbulence phenomenology is very different in wave‐dominated regimes when compared to the quasi‐geostrophic regime. Motivated by these recent investigations revealing significant differences in the flow dynamics in quasi‐geostrophic and wave‐dominated regimes and multiple oceanic observations pointing out enhanced tracer stirring at submesoscales, in this paper we compare and contrast passive tracer dispersion by barotropic flows in quasi‐geostrophic and wave‐dominated turbulent regimes using the reduced model explored by Thomas and Yamada (2019), https://doi.org/10.1017/jfm.2019.465. On comparing passive tracer dispersion by barotropic flows in the two different regimes, we find that wave‐dominated turbulent flows stir and mix tracer fields much more rapidly than quasi‐geostrophic turbulent flows that consist of well‐defined coherent vortices. The presence of energetic small‐scale features in wave‐dominated flows increases small‐scale turbulent diffusivity and results in steeper tracer variance spectrum in wave‐dominated flows compared to the quasi‐geostrophic flows. Our findings point out that gravity waves can play an indirect role in enhancing tracer dispersion: waves modify the flow, generating energetic small‐scale structures, that makes stirring of tracers more efficient. Despite our study being idealized, we speculate the qualitative phenomenology of waves indirectly enhancing tracer dispersion to be of significance at submesoscales in the world's oceans.

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“…Indeed, due to high-frequency winds and tidal motions, energy extraction via IGWs seems to be a highly probable mechanism of kinetic energy sinks for balanced motions (J. Thomas & Daniel, 2021). From a theoretical standpoint, there are so far essentially two well known and documented energy transfer mechanisms from balanced motions to IGWs away from topography, namely the stimulated generation of a forward cascade of kinetic energy by nearinertial waves from balanced flows (Gertz & Straub, 2009;Rocha et al, 2018;Barkan et al, 2021) and the spontaneous generation of near-inertial waves from balanced flows (Nagai et al, 2015;Shakespeare & Hogg, 2017).…”

Section: Introductionmentioning

confidence: 99%

On the modulation of kinetic energy transfer by internal gravity waves

Ajayi¹,

Sommer²,

Brodeau³

et al. 2022

Preprint

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Understanding how kinetic energy (KE) is exchanged across scales and eventually dissipated remains a key question in physical oceanography. Recent theoretical works suggests that both quasi-balanced submesoscale motions and internal gravity waves (IGWs) could play a role in fluxing KE towards dissipation. How these classes of motions actually provide a route to dissipation in the ocean is still debated. This study investigates the impact of IGWs generated by tidal motions on cross-scale KE exchanges at mid-latitude. Our analysis is based on the output of two realistic submesoscale permitting ocean model simulations of the North Atlantic Ocean, run respectively with and without tidal forcing. These twin experiments permit investigation of how tidally-forced IGWs modify the KE variance, cross-scale exchanges, and associated seasonality. Our results show that, in the presence of externally-forced IGWs, KE transfer towards dissipative scales is enhanced in summertime both at the surface and in the ocean interior.

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Forward flux and enhanced dissipation of geostrophic balanced energy

Abstract: Abstract

Cited by 18 publications

References 48 publications

Oceanic Mesoscale Eddy Depletion Catalyzed by Internal Waves

Oceanic Mesoscale Eddy Depletion Catalyzed by Internal Waves

Wave‐Enhanced Tracer Dispersion

On the modulation of kinetic energy transfer by internal gravity waves

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