Modeling mesoscale eddies

Canuto, V.; Dubovikov, M. S.

doi:10.1016/j.ocemod.2003.11.003

Cited by 28 publications

(18 citation statements)

References 53 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Details of the analytical expression of Γ (z) are given and validated versus observation data in Canuto and Dubovikov (2005). An interpretation of (9)-(11) is discussed in the appendix A.…”

Section: Parametrisationmentioning

confidence: 99%

“…The CD11-parametrisation is a nonlinear extension of a widespread oceanography method, which is based on solving dynamical equations for mesoscale and other turbulent fields within the linear approximation. The nonlinear approach (hereafter referred to as CD5) to mesoscale analysis was applied first by Dubovikov (2003) and Canuto and Dubovikov (2005) in the ocean interior. It constitutes a simplified version of the general approach developed by 35 Dubovikov during 1996-1998 (see the appropriate list of their publications in Dubovikov 2003).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effects of mesoscale eddies in the active mixed layer: test of the parametrisation in eddy resolving simulations

Luneva

Clayson

Dubovikov

2015

Geophysical & Astrophysical Fluid Dynamics

View full text Add to dashboard Cite

In eddy resolving simulations, we test a mixed layer mesoscale parametrisation, developed recently by Canuto and Dubovikov [Ocean Model., 2011, 39, 200-207]. With no adjustable parameters, the parametrisation yields the horizontal and vertical mesoscale fluxes in terms of coarse-resolution fields 10 and eddy kinetic energy (EKE). We compare terms of the parametrisation diagnosed from coarsegrained fields with the eddy mesoscale fluxes diagnosed directly from the high resolution model. An expression for the EKE in terms of mean fields has also been found to get a closed parametrisation in terms of the mean fields only. In 40 numerical experiments we simulated two types of flows: idealised flows driven by baroclinic instabilities only, and more realistic flows, driven by wind and 15 surface fluxes as well as by inflow-outflow. The diagnosed quasi-instantaneous horizontal and vertical mesoscale buoyancy fluxes (averaged over 1 • -2 • and 10 days) demonstrate a strong scatter typical for turbulent flows, however, the fluxes are positively correlated with the parametrisation with higher (0.5 − 0.74) correlations at the experiments with larger baroclinic radius Rossby. After being averaged over 3-4 months, diffusivities diagnosed from the eddy resolving simulations are consistent with the 20 parametrisation for a broad range of parameters. Diagnosed vertical mesoscale fluxes restratify mixed layer and are in a good agreement with the parametrisation unless vertical turbulent mixing in the upper layer becomes strong enough in comparison with mesoscale advection. In the latter case, numerical simulations demonstrate that the deviation of the fluxes from the parametrisation is controlled by dimensionless parameter estimating the ratio of vertical turbulent mixing term to mesoscale advection. 25An analysis using a modified ω-equation reveals that the effects of the vertical mixing of vorticity is responsible for the two-three fold amplification of vertical mesoscale flux. Possible physical mechanisms, responsible for the amplification of vertical mesoscale flux are discussed.

show abstract

Section: Parametrisationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of mesoscale eddies in the active mixed layer: test of the parametrisation in eddy resolving simulations

Luneva

Clayson

Dubovikov

2015

Geophysical & Astrophysical Fluid Dynamics

View full text Add to dashboard Cite

show abstract

“…It is a global ocean model that covers the region from 75 • S to 88 • N, and the North Pole is modeled as an isolated island. In particular, the model's dynamical framework is based on a latitudelongitude grid system with 1 • × 1 • horizontal resolution; however, the meridional resolution increases to 0.5 • between 10 • S and 10 • N, and there are 30 layers with 15 equal-depth levels in the upper 150 m. The model adopts some new physical parameterization schemes, such as a new turbulent mixing scheme (Canuto and Dubovikov, 2005), solar radiation penetration, and an improved isopycnal-mixing scheme (Gent and Williams, 1990;Large et al, 1997). It can well reproduce the basic temporal and spatial structures of the observed ENSO and IOD, especially the significant asymmetry between El Niño and La Niña events, as well as positive and negative IOD events (Hua et al, 2010).…”

Section: Modelmentioning

confidence: 99%

Nonlinear responses of oceanic temperature to wind stress anomalies in tropical Pacific and Indian Oceans: A study based on numerical experiments with an OGCM

Hua

2015

J Meteorol Res

View full text Add to dashboard Cite

As a highly nonlinear dynamic system, oceanic general circulation models (OGCMs) usually exhibit nonlinear responses to prescribed wind stress forcing. To explore mechanisms for these nonlinear responses, we designed and conducted three idealized numerical experiments with an OGCM with modified wind stress forcing. In the experiments, the climatological mean wind stress was identical, and the only differences in external forcing were wind stress anomalies. The wind anomalies were set to zero in a control run, and the observed wind stress anomalies with and without reversed signs were superimposed on the mean climatology in two sensitivity experiments. Forced by the prescribed wind stress anomalies in sensitivity runs, the OGCM well reproduced the El Niño-Southern Oscillation (ENSO) and the Pacific and Indian Ocean Dipole (IOD) in the Indian Ocean, as well as the asymmetry between positive and negative phases of these modes. Relative to the control run, the two sensitivity runs exhibited almost identical changes in the mean climate state, although the wind stress anomalies were reversed in these two experiments. Thus, it was concluded that the asymmetry of wind stress anomalies contributes only slightly to the mean state changes and ocean internal dynamics was the main contributor. Further heat budget analysis suggested that nonlinear temperature advection terms, including both mean advection and perturbed advection, favor the ENSO/IOD rectified effect on the mean state. Citation: Hua Lijuan and Yu Yongqiang, 2015: Nonlinear responses of oceanic temperature to wind stress anomalies in the tropical Pacific and Indian Oceans: A study based on numerical experiments with an OGCM.

show abstract

“…(Muller, McWilliams and Molemaker, 2002). To study this as yet unsolved problem, we introduce in the analysis a dynamical consideration based on the mesoscale model developed by Dubovikov (2003) and Canuto and Dubovikov (2005) within which in a quasi-adiabatic ocean interior the large scale baroclinic instability generates mesoscale eddy potential energy (EPE) at scales of the Rossby deformation radius~d r . Since at those scales the mesoscale Rossby number is small, the generated EPE cannot convert into eddy kinetic energy (EKE) and cascades to smaller scales at which the spectral Rossby number increases until at some horizontal scales it reaches .…”

Section: Introductionmentioning

confidence: 99%

“…As discussed by Kraichnan (1965Kraichnan ( , 1967, in 2D flows only inversed (upscale) energy cascades are possible. Dubovikov (2003, D3) and Canuto and Dubovikov (2005, CD5) argued that mesoscale eddy energy (EKE) does cascade upscale, a process that is now commonly recognized (Ferrari and Wunsch, 2009;Bruggemann and Eden, 2015;Jansen et al, 2015) and confirmed by sea surface height (SSH) data (Scott and Wang, 2005;Scott and Arbic, 2007). It is worth noticing that the mentioned energy cascade is rather different than that in the two-level geostrophic model (Salmon, 1978(Salmon, ,1980(Salmon, , 1998 within which at scales larger than the Rossby deformation radius d r there are the down-scale baroclinic energy cascade and the upscale barotropic one while at scales less than d r both cascades are directed down-scale.…”

Section: Introductionmentioning

confidence: 99%

Mesoscale cascades and the conundrum of energy transfer from large to dissipation scales in an adiabatic ocean

Dubovikov

2017

Preprint

View full text Add to dashboard Cite

A well-known "conundrum" in ocean dynamics has been expressed as follows: "How does the energy of the general circulation cascade from the large climate scales, where most of it is generated, to the small scales, where all of it is dissipated? In particular, how is the dynamical transition made from an anisotropic, 2D-like, geostrophic cascade at large scales-with its strong inhibition of down-scale energy flux-to 3D-like, down-scale cascades at small scales." (Muller, McWilliams and Molemaker, 2002). To study this as yet unsolved problem, we introduce in the analysis a dynamical consideration based on the mesoscale model developed by Dubovikov (2003) and Canuto and Dubovikov (2005) within which in a quasi-adiabatic ocean interior the large scale baroclinic instability generates mesoscale eddy potential energy (EPE) at scales of the Rossby deformation radius~d r . Since at those scales the mesoscale Rossby number is small, the generated EPE cannot convert into eddy kinetic energy (EKE) and cascades to smaller scales at which the spectral Rossby number increases until at some horizontal scales it reaches . Under this condition, EPE converts into EKE and thus the cascade of the former terminates while the inverse EKE cascade begins. At scales ~d r the inverse EKE cascade terminates and reinforces the EPE cascade produced by the large scale baroclinic instability thus closing the mesoscale energy cycle. If the flow were exactly adiabatic, i.e. eddy energy were not dissipated, the latter would increase unlimitedly at the expense of the permanent production of the total eddy energy (TEE) by the mean flow. However, at the same scales where the EPE cascade terminates and the inverse EKE cascade begins, the vertical eddy shear reaches the value of the buoyancy frequency N that gives rise to the Kelvin-Helmholtz instability. The latter generates the stratified turbulence which finally dissipates EKE. A steady state regime sets in when the dissipation balances the TEE production by the mean flow.() Ro k( 1/ )~1 RoÕ cean Sci. Discuss., doi:10.5194/os-2017Discuss., doi:10.5194/os- -23, 2017 Manuscript under review for journal Ocean Sci. 1.IntroductionFor a long time it is recognized that one of the most enigmatic conundrums of ocean general circulation is: "how and where does the energy of the general circulation cascade from the large climatic scales, where most of it is generated, to the small scales, where all of it is dissipated?" "In particular, how is the dynamical transition made from a 2-D like geostrophic cascade at large scales-with its strong inhibition of down-scale energy flux-to the more isotropic, 3D-like, downscale cascades at small scales" (Muller et al., 2002; Mc Williams, 2003). In fact, interior ocean flows in the adiabatic approximation are sets of 2D ones within isopycnal surfaces between which non-linear interactions vanish. As discussed by Kraichnan (1965Kraichnan ( , 1967, in 2D flows only inversed (upscale) energy cascades are possible. Dubovikov (2003, D3) and Canuto and Dubovikov (2005...

show abstract

Modeling mesoscale eddies

Cited by 28 publications

References 53 publications

Effects of mesoscale eddies in the active mixed layer: test of the parametrisation in eddy resolving simulations

Effects of mesoscale eddies in the active mixed layer: test of the parametrisation in eddy resolving simulations

Nonlinear responses of oceanic temperature to wind stress anomalies in tropical Pacific and Indian Oceans: A study based on numerical experiments with an OGCM

Mesoscale cascades and the conundrum of energy transfer from large to dissipation scales in an adiabatic ocean

Contact Info

Product

Resources

About