Equatorward Energy Cascade, Critical Latitude, and the Predominance of Cyclonic Vortices in Geostrophic Turbulence

Theiss, J.

doi:10.1175/1520-0485(2004)034<1663:eeccla>2.0.co;2

Cited by 79 publications

(92 citation statements)

References 17 publications

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“…Despite the differences in the formulation, both studies find that small L d (less than a few thousand km) suppresses the β effect, leading to the production of numerous vortices rather than jets. This is consistent with one-layer studies using the simpler quasigeostrophic (QG) equations (Okuno and Masuda 2003;Smith 2004;Theiss 2004). Because L d decreases with increasing latitude (an effect of increasing Coriolis parameter), a critical latitude typically exists below which the flow is jet-dominated and above which the flow is vortex dominated.…”

Section: Models For Jet Pumpingmentioning

confidence: 91%

Saturn Atmospheric Structure and Dynamics

Genio

Achterberg

Baines

et al. 2009

Saturn From Cassini-Huygens

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Section: Models For Jet Pumpingmentioning

confidence: 91%

Saturn Atmospheric Structure and Dynamics

Genio

Achterberg

Baines

et al. 2009

Saturn From Cassini-Huygens

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“…The staircase found by Danilov and Gurarie (2004) The inversions (5.1) and (5.3) assume straight jets. Recent work on shallow-water flows with a latitudinal variation of L D like that expected on Jupiter (e.g., Theiss 2004;Scott and Polvani 2007), following ideas of Salmon (1982), suggest that for the smaller values of L D , as in modeling Jupiter's high latitudes, the jets not only become thinner but meander strongly as well, while keeping themselves sharp. This is also reminiscent of many terrestrial ocean currents (e.g., Niiler et al 2003).…”

Section: ͑56͒mentioning

confidence: 98%

Multiple Jets as PV Staircases: The Phillips Effect and the Resilience of Eddy-Transport Barriers

Dritschel

McIntyre

2008

Journal of the Atmospheric Sciences

283

347

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A review is given that focuses on why the sideways mixing of potential vorticity (PV) across its background gradient tends to be inhomogeneous, arguably a reason why persistent jets are commonplace in planetary atmospheres and oceans, and why such jets tend to sharpen themselves when disturbed. PV mixing often produces a sideways layering or banding of the PV distribution and therefore a corresponding number of jets, as dictated by PV inversion. There is a positive feedback in which mixing weakens the "Rossby wave elasticity" associated with the sideways PV gradients, facilitating further mixing. A partial analogy is drawn with the Phillips effect, the spontaneous layering of a stably stratified fluid, in which vertically homogeneous stirring produces vertically inhomogeneous mixing of the background buoyancy gradient. The Phillips effect has been extensively studied and has been clearly demonstrated in laboratory experiments. However, the "eddy-transport barriers" and sharp jets characteristic of extreme PV inhomogeneity, associated with strong PV mixing and strong sideways layering into Jupiter-like "PV staircases," with sharp PV contrasts ⌬q barrier , say, involve two additional factors besides the Rossby wave elasticity concentrated at the barriers. The first is shear straining by the colocated eastward jets. PV inversion implies that the jets are an essential, not an incidental, part of the barrier structure. The shear straining increases the barriers' resilience and amplifies the positive feedback. The second is the role of the accompanying radiation-stress field, which mediates the angular-momentum changes associated with PV mixing and points to a new paradigm for Jupiter, in which the radiation stress is excited not by baroclinic instability but by internal convective eddies nudging the Taylor-Proudman roots of the jets.Some examples of the shear-straining effects for strongly nonlinear disturbances are presented, helping to explain the observed resilience of eddy-transport barriers in the Jovian and terrestrial atmospheres. The main focus is on the important case where the nonlinear disturbances are vortices with core sizes ϳL D , the Rossby (deformation) length. Then a nonlinear shear-straining mechanism that seems significant for barrier resilience is the shear-induced disruption of vortex pairs. A sufficiently strong vortex pair, with PV anomalies Ϯ⌬q vortex , such that ⌬q vortex k ⌬q barrier , can of course punch through the barrier. There is a threshold for substantial penetration through the barrier, related to thresholds for vortex merging. Substantial penetration requires ⌬q vortex տ ⌬q barrier , with an accuracy or fuzziness of order 10% when core size ϳL D , in a shallow-water quasigeostrophic model. It is speculated that, radiation stress permitting, the barrierpenetration threshold regulates jet spacing in a staircase situation. For instance, if a staircase is already established by stirring and if the stirring is increased to produce ⌬q vortex values well above threshold, then the s...

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“…Using the same method as Pedlosky (1984), Theiss (2004) formulated a 1.5-layer quasi-geostrophic model with a latitude-dependent deformation radius. Here we also use the method and scaling in Pedlosky (1984) and formulate a 1.5-layer model suitable for our study purpose.…”

Section: Model Formulationmentioning

confidence: 99%

Energy pathways and structures of oceanic eddies from the ECCO2 state estimate and simplified models

Chen¹

2013

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Studying oceanic eddies is important for understanding and predicting ocean circulation and climate variability. The central focus of this dissertation is the energy exchange between eddies and mean flow and banded structures in the low-frequency component of the eddy field. A combination of a realistic eddy-permitting ocean state estimate and simplified theoretical models is used to address the following specific questions. (1) What are the major spatial characteristics of eddy-mean flow interaction from an energy perspective? Is eddy-mean flow interaction a local process in most ocean regions? (2) The banded structures in the low-frequency eddy field are termed striations. How much oceanic variability is associated with striations? How does the time-mean circulation, for example a subtropical gyre or constant mean flow, influence the origin and characteristics of striations? How much do striations contribute to the energy budget and tracer mixing?

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Equatorward Energy Cascade, Critical Latitude, and the Predominance of Cyclonic Vortices in Geostrophic Turbulence

Cited by 79 publications

References 17 publications

Saturn Atmospheric Structure and Dynamics

Saturn Atmospheric Structure and Dynamics

Multiple Jets as PV Staircases: The Phillips Effect and the Resilience of Eddy-Transport Barriers

Energy pathways and structures of oceanic eddies from the ECCO2 state estimate and simplified models

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