Georgi Sutyrin

University of Rhode Island | URI · Graduate School of Oceanography

We identify and explore the fundamental differences in the dynamics of mesoscale vortices in eastward background (EB) parts in mid-latitude ocean gyres and in westward background (WB) return flows. In contrast to eddy behavior in EB flow, a systematic meridional drift of eddies in WB flow results in poleward expulsion of cold-core cyclones and equa...

We explore the dynamics of baroclinic instability in westward flows using an asymptotic weakly nonlinear model. The proposed theory is based on the multilayer quasi-geostrophic framework, which is reduced to a system governed by a single nonlinear prognostic equation for the upper layer. The dynamics of deeper layers are represented by linear diagn...

This paper examines baroclinic turbulence in the local approximation using a quasi-geostrophic beta-plane numerical model with bottom friction. New coherent vortex structures are found to emerge and self-amplify in a horizontally homogeneous mean flow directed westward in the upper layer where the potential vorticity gradient (PVG) is negative. Opp...

This paper examines baroclinic vortices embedded in a large-scale vertical shear. We describe a new class of steady propagating vortices that radiate Rossby waves but yet do not decay. This is possible since they can extract available potential energy from a large-scale vertically sheared flow, even though this flow is linearly stable. The vortices...

This paper examines factors contributing to the remarkable longevity of coherent vortices in the subtropical westward flows. Baroclinic vortices embedded in large-scale vertical shears generate Rossby waves which form an opposite sign eddy associated with inertial Taylor columns on the beta-plane. The combination of the vortex and lee Rossby wave c...

Purpose. The article is aimed at substantiating theoretically amazing longevity (up to 5 years) of the individual vortices in the World Ocean against the background of strong fluctuations of the ocean currents and regardless of the Rossby wave dispersion features. Methods and Results. Evolution of the baroclinic vortices is considered in a hybrid...

The structure of circular baroclinic vortices in rotating stratified fluids is examined in order to rationalize the observed amplification of fluid rotation inside long-lived geophysical vortices during their evolution. New relations between basic vortex parameters at horizontal mid-depth are derived in order to compare vortices with the same poten...

The evolution of a monopolar vortex embedded in the field of smaller-scale randomly forced vorticity is examined using fully nonlinear two-dimensional simulations at large Reynolds numbers. The vortex is considered to be compact if its angular momentum decreases with the radius on the scale comparable to the radius of maximum azimuthal velocity. Th...

The interaction of two essentially unequal vortices is studied for the two-dimensional inviscid model. The curved stretching out of a weak satellite, localized at the periphery of the main vortex, is described analytically in the passive scalar approximation. The rate of energy transfer from the satellite to the main vortex is shown to increase wit...

Superpositions of Lamb-Oseen axisymmetric vortices with Gaussian vorticity having zero net circulation and finite kinetic energy in unbounded domain are considered. Their evolution is described by self-similar solutions depending on a certain combination of space, time, and viscous diffusion. It is shown that the structure of a popular self-similar...

The analysis of satellite and hydrological data indicates that long-lived eddies are not satisfactory reproduced in existing global eddy-resolving numerical models. There are several physical mechanisms of baroclinic vortex intensification during their evolution are considered. It is argued that the spatially inhomogeneous mixing, symmetrization of...

Nonlinear evolution of pancake-like vortices in a uniformly rotating and stratified fluid is studied using a 3D Boussinesq numerical model at large Rossby numbers. After the initial stage of viscous decay, the simulations reveal exponential growth of toroidal circulation cells (aka Taylor vortices) at the peripheral annulus with a negative Rayleigh...

The key element of Geophysical Fluid Dynamics-reorganization of potential vorticity (PV) by nonlinear processes-is studied numerically for isolated vortices in a uniform environment. Many theoretical studies and laboratory experiments suggest that axisymmetric vortices with a Gaussian shape are not able to remain circular owing to the growth of sma...

Wide compensated vortices are not able to remain circular in idealized two-layer models unless the ocean depth is assumed to be unrealistically large. Small perturbations on both cyclonic and anticyclonic eddies grow slower if a middle layer with uniform potential vorticity (PV) is added, owing to a weakening of the vertical coupling between the up...

In contrast to many real-ocean rings and eddies, circular vortices in idealized two-layer models tend to be highly unstable, unless their radius is made small or their baroclinicity is made artificially weak. The addition of a middle layer with uniform potential vorticity weakens vertical coupling between the upper and lower layers that enhances vo...

The initial evolution of a baroclinic jet under influence of a barotropic flow induced by the tropical cyclones is considered using a two-layer model and the thin-jet approximation. In spite of antisymmetric structure of the barotropic flow, the jet meander growth due to the barotropic flow advection is shown to favor an anticyclonic meander to the...

Strong energy in the 30–60 day band was observed using 39 deep pressure and current records from the Kuroshio Extension System Study (KESS). Energy in this band accounted for 25–50% of the total deep-pressure variance and was strongest under the Kuroshio Extension jet axis. Often, deep-pressure anomalies propagated into the region from the north-no...

The transformation of baroclinic eddies encountering a tall seamount is explored using a three-layer primitive equation model on the β-plane. The topography is finite in that the seamount penetrates the isopycnal layer in which the eddy resides, but does not span the entire fluid depth. In our numerical simulations, the eddies are represented by po...

We consider the evolution of an isolated anticyclonic vortex encountering a continental shelf during its westward β-drift in the framework of an equivalent-barotropic model generalized to allow for the intersection of the layer interface with a sloping bottom. The approaching vortex generates both topographic coastally trapped waves, and secondary...

The transformation of Agulhas eddies near the continental slope of South Africa and their subsequent self-propagation are analyzed in both observational data and numerical simulations. Self-propagation results from a net dipole moment of a generalized heton structure consisting of a surface-intensified anticyclonic eddy and deep cyclonic pattern. S...

The datasets of the Eddies and Gyre Path Tracking (EGYPT)/EGITTO program in the eastern Mediterranean Sea reveal a large mesoscale anticyclone traveling along the Libyan shelf. Surface drifter trajectories combined with a CTD transect accurately quantify the horizontal velocity and the vertical structure of this surface-intensified anticyclone. The...

We consider the evolution of an isolated anticyclonic vortex encountering a continental shelf during its westward β-drift in the framework of an equivalent-barotropic model generalized to allow for the intersection of the layer interface with a sloping bottom. The approaching vortex generates both topographic coastally trapped waves, and secondary...

Strong deep eddies with cyclonic vorticity greater than 0.2f 0 were detected using an array of bottom current and pressure measurements in the Kuroshio Extension System Study (KESS) in 2004–2006. Daily maps showed these deep eddies developed locally. As in the Gulf Stream, meandering of the upper baroclinic jet generates deep cyclones and anticyclo...

Periodic linear waves in a vertically sheared flow are considered in a continuously stratified layer of rotating fluid between homogeneous layers along a sloping bottom. This generalized Phillips' configuration has cyclonic horizontal shear and supports the Rossby modes related to the thickness variations of the homogeneous layers and inertia–gravi...

Vortices have been recognized to be key elements in turbulent fluid motion at a wide range of scales. The Coriolis force at rotating planets, galaxies or Lorentz force due to magnetic field in plasmas makes large-scale flows anisotropic, quasi-two-dimensional (e.g., the horizontal velocity of oceanic currents is much larger than vertical velocity)....

The evolution of a self-propelling vortex dipole, embedded in an external nondivergent flow with constant potential vorticity, is studied in an equivalent-barotropic model commonly used in geophysical, astrophysical and plasma studies. In addition to the conservation of the Hamiltonian for an arbitrary point vortex dipole, it is found that the angu...

The motion of a localized vortex on the beta-plane, in the presence of a long Rossby wave, is studied with an asymptotic theory and via numerical simulations in an equivalent-barotropic quasi-geostrophic model. The initial phase of the wave is chosen to obtain maximum horizontal shear on the vortex core. This shear modifies the vortex drift via the...

A Lagrangian approach is formulated for rotating stratified axisymmetric flows. The moment of inertia for compact flows with finite energy is shown to oscillate with inertial frequency. In particular, any steady axisymmetric solution for a finite volume inviscid anticyclonic vortex with outcropping isopycnals corresponds to a set of self-similar an...

The normal modes of a horizontally uniform, vertically sheared flow over a sloping bottom are considered in two active layers underneath a deep motionless third layer. The variations of the layer thickness are assumed to be small to analyse the sixth-order eigenvalue problem for finite-Froude-number typical for oceanic currents. The dispersion curv...

We consider interactions between the two most important components of the atmosphere and ocean dynamics: slowly evolving vortical motion and inertia-gravity waves in rotating stratified axisymmetric flows. Any steady axisymmetric solution for a finite volume anticyclonic vortex with outcropping isopycnals is known to correspond to a set of self-sim...

The ageostrophic normal modes of a spatially uniform, vertically sheared flow along a sloping bottom are considered in two layers underneath a deep motionless third layer (two-and-half layer model). The variations of the layer thickness are assumed to be small to derive the six-order dispersion relation with constant coefficients valid for finite F...

Self-similar analytical nonlinear solutions to the hydrostatic Boussinesq equations are derived which describe unbalanced inertial pulsations of anticyclonic lens-like circular vortices in stably stratified rotating fluid. Any steady axisymmetric solution for a finite-volume anticyclonic vortex in the reduced-gravity approximation is shown to corre...

An analytical theory is presented for the motion of a localized vortex in the presence of a zonal Rossby wave on the β-plane. In the framework of the equivalent-barotropic quasi-geostrophic model, the analytical method developed by Sutyrin and Flierl [Sutyrin G.G., Flierl G.R., 1994. Intense vortex motion on the β-plane: development of the beta gyr...

The initial-value problem for the evolution of an isolated vortex encountering a tall seamount during its westward beta-drift is studied within an equivalent-barotropic model, that is generalized to allow for the intersection of the layer interface with a sloping bottom. Given the Rossby radius and linear wave speed in the model, the parabolic shap...

The propagation of compact, surface-intensified vortices on the β-plane is studied in the framework of a two-layer model with sloping topography. In contrast with previous work, we consider here bottom friction, modeled by an Ekman suction term. A perturbation theory is derived for a circular vortex in the upper layer with the lower layer at rest a...

The evolution of a localized flow in a half-plane bounded by a rigid wall is analysed when the total mass is not conserved within the equivalent-barotropic quasi-geostrophic (QG) approximation. A simple formula expressing the total geostrophic mass in terms of the QG potential vorticity is derived and used to estimate the range of the geostrophic m...

Current and temperature patterns in the Ulleung Basin of the Japan/East Sea are examined using acoustic travel-time measurements from an array of pressure-gauge-equipped inverted echo sounders moored between June 1999 and July 2001. The focus here is the formation and behavior of a persistent cold eddy observed south of Dok Island, referred to as t...

A two-layer, intermediate equations model that, uniquely, allows for the intersection of the bathymetry with the layer interface is used to study the interaction of isolated Loop Current Eddy (LCE)-type anticyclones with western-boundary topography. Two idealized topography configurations representative of the Gulf of Mexico (GoM) coastal topograph...

A new approach to modelling slow vortical motion and fast inertia-gravity waves is suggested within the rotating shallow-water primitive equations with arbitrary topography. The velocity is exactly expressed as a sum of the gradient wind, described by the Bernoulli function, B, and the remaining agradient part, proportional to the velocity tendency...

The propagation of compact, surface-intensified vortices on the -plane is studied in the framework of a two-layer model with sloping topography. A perturbation theory is derived for a circular vortex in the upper layer with the lower layer at rest as a basic state. An integral momentum balance for the upper layer is used to obtain expressions for t...

The symmetry properties of the Gulf Stream-type jet equilibrated over topographic slope are investigated in a series of idealized numerical experiments. A baroclinically unstable zonal jet equilibrates over a sloping bottom through the process of potential vorticity (PV) homogenization underneath the main thermocline by the bottom-intensified eddy...

We analyze an evolution of a localized flow in a half-plane bounded by a rigid wall when the total mass is not conserved within the equivalent-barotropic quasigeostrophic (QG) approximation. A simple formula expressing the total geostrophic mass in terms of the QG potential vorticity is derived and used to estimate the range of the geostrophic mass...

Summary A new approach to consider balance dynamics for modelling slow vortical motion is suggested within the rotating shallow water primitive equations. Instead of a traditional approach using divergence and ageostrophic vorticity as fast variables, the velocity is exactly expressed as a sum of the gradient part, described by a Bernoulli function...

Form-preserving, uniformly translating, horizontally localized solutions (modons) are considered within the framework of nondissipative quasi-geostrophic dynamics for a two-layer model with meridionally sloping bottom. A general classification of the beta-plane baroclinic topographic modons (-BTMs) is given, and three distinct domains are shown to...

The evolution and propagation of large anticyclonic eddies similar to the Loop Current eddies found in the Gulf of Mexico are studied in a two-layer intermediate equation numerical model. It is found that the propagation of these eddies is governed primarily by the β effect, lower-layer flow driven by the surface eddies, and the image effect. As th...

The authors study the splitting of a coherent vortex by a large-scale baroclinic background current. A criterion for the splitting of the vortex is defined, and the process is then studied numerically and analytically in a 21/2 layer reduced-gravity model in which the vortex is represented by a potential vorticity (PV) patch in each layer. Three ef...

Evolution of baroclinic eddies in the presence of topography is analyzed by means of asymptotic expansion and numerical investigation. The flow in the lower layer over topography is assumed to be adjusted to slow evolution of the lower interface by topographic Rossby wave radiation. Resuling feedback to the upper layers flow is calculated for diffe...

The propagation of compact, surface-intensified vortices over a topographic slope on the beta-plane is studied in the framework of a two-layer model. A perturbation theory is derived for a circular vortex in the upper layer with the lower layer at rest as a basic state. An integral momentum balance for the upper layer is used to obtain expressions...

The nonlinear interaction of a localized vortex with a vertically sheared mean flow has been studied using numerical and asymptotic methods in a multilayer quasigeostrophic model on the beta plane. Numerical solutions indicate that baroclinic large-scale flows have a weak influence on the translation of coherent vortices, even when the advective ef...

Spatiotemporal evolution of a small localized meander on a Gulf Stream-type baroclinically unstable jet over a topographic slope is investigated numerically using a three-dimensional, primitive equation model. An un- perturbed jet is prescribed by a potential vorticity front in the upper thermocline overlaying intermediate layers with weak isentrop...

The theory of solitary topographic Rossby waves (modons) in a uniformly rotating two-layer ocean over a constant slope is developed. The modon is described by an exact, form-preserving, uniformly translating, horizontally localized, nonlinear solution to the inviscid quasi-geostrophic equations. Baroclinic topographic modons are found to transl...

Potential vorticity (PV) structure across a baroclinic front is a property that determines the stability characteristics of that front, cross-frontal exchange, and the behavior of the vortical waves that this front enables. Hence, there has been much interest in estimating PV across the Gulf Stream (GS). However, PV estimations have typically encou...

Spatio-temporal evolution of meanders on a baroclinically unstable jet over a topographic slope is investigated using pulse asymptotics and numerical simulations. An unperturbed jet is prescribed by a potential vorticity front in the upper layer overlaying intermediate layers with weak potential vorticity gradients and a quiescent bottom layer over...

The properties of solitary topographic Rossby waves (modons) in a uniformly rotating two-layer ocean over a constant slope are analyzed. The modon is described by exact, form preserving, uniformly translating, horizontally localized, nonlinear solution to the inviscid quasigeostrophic equations. Baroclinic modons over topography are found to transl...

The upper ocean response to idealized surface wind forcing that is representative of conditions observed during the TOGA-COARE Intensive Observation Period is studied by numerical simulations using a second-moment closure model. A set of experiments is described with a variety of squall-like wind stress distributions and linear initial stratificati...

We investigate the evolution of nearby like-sign vortices whose centres are at different vertical levels in a stably stratified rotating fluid. We employ two differently singularized representations of the potential vorticity distribution in the quasi-geostrophic equations (QG), in order to elucidate the pair-interaction behaviour previously seen i...

This paper deals with the self-induced translation of intense vortices on the β-plane in the framework of the multi-layer quasi-geostrophic approximation. An analytical theory is presented and compared to numerical experiments. To predict the vortex trajectories, we consider initially monopolar vortices, with a core of piecewise-constant potential...

The barotropic response is analysed for different wind stress distribution. A universal nondimensional description of the depth-averaged flow is suggested, using scaling based on the maximum wind stress torque LTL and its radius L. This marks the primary difference with baroclinic responses where the radius of maximum winds, Rm, and maximum wind st...

The existence and dynamics of vortical structure in both homogeneous and inhomogeneous systems will be discussed. In particular the dynamics of monopolar and dipolar vortices in a plasma with nonuniform density and in a rotating fluid with varying Coriolis force is described. The role of vortical structures in connection with electrostatic plasma t...

Large, long-lived vortices, surviving during many turnaround times and far longer than the dispersive linear Rossby wave packets, are abundant in planetary atmospheres and oceans. Nonlinear effects which prevent dispersive decay of intense cyclones and anticyclones and provide their self-propelling propagation are revised here using shallow water e...

The long-time evolution of monopolar and dipolar vortices influenced by the largescale gradient of the ambient potential vorticity (the β-effect) is studied by direct numerical solutions of the equivalent barotropic quasi-geostrophic equation. Translation and reorganization of vortical structures are shown to depend strongly on their intensity. Tra...

Large, long-lived vortices are abundant in the atmospheres of the giant planets. Some of them survive a few orders of magnitude longer than the dispersive linear Rossby wave packets, e.g. the Great Red Spot (GRS), Little Red Spot (LRS) and White Ovals (WO) of Jupiter, Big Bertha, Brown Spot and Anne's Spot of Saturn, the Great Dark Spot (GDS) of Ne...

An analytical theory is presented for the self-induced translation of an intense vortex relative to a uniform background flow on the β plane. The equivalent barotropic approximation is used to formulate the initial value problem within a polar coordinate frame translating with the vortex center. A contour dynamical model of the vortex is melded wit...

A new feature of the long‐time evolution of a strong vortex with initially monotonic potential vorticity is found by direct numerical solution of the quasigeostrophic equivalent barotropic equation. Two satellites, which emerge after splitting of an annulus, appear at the vortex periphery. Rotation and oscillation of the tripolar structure may lead...

A simple equation is derived for the nonlinear evolution of a front (a potential-vorticity discontinuity) in the rotating shallow-water equations, assuming weak along-front variations relative to the internal radius of deformation. This equation can be transformed into the modified Korteweg–de Vries equation, which is integrable and possesses exact...

A fundamental property of two-dimensional flows is the ability to support the existence of longlived, isolated vortical structures. Vortices in the form of monopoles, dipoles and tripoles are often encountered, e. g. in the atmosphere and oceans of large planets as well as in laboratory experiments. Such propagating structures may trap particles an...

Observations show a lot of coherent vortices in the World ocean with quick fluid rotation in their cores during long life time. To explain this feature, isopycnal balanced models of a circular vortex evolution with different variants of turbulent closure for isopycnal mixing considered. A linear dependence of the mixing coefficient on the local she...

Approximately stationary anticyclones in shallow water on a rotating planet are studied both analytically and numerically. They consist of a monopolar part with large amplitude and a dipolar part with small amplitude, proportional to the beta parameter. An explicit solution for the dipolar part is o obtained with an arbitrary radial profile of the...

An asymptotic theory of two-dimensional planetary solitary eddies is presented. Previous studies in one-and-a-half layer models have discovered special classes of radially symmetric structure which are associated with eddies of permanent form. We generalize these studies by including an active lower layer and by considering the effects of azimuthal...

Although the quasigeostrophic formalism has been a cornerstone in oceanographic modeling for over four decades, studies have shown time and time again that other geostrophic, but non-quasigeostrophic, regimes can also exist. These include a particular class of regimes representative of oceanic fronts and frontal eddies. The task undertaken here is...

The filtered shallow water model which allows order-one variations of the potential vorti-city is used for modelling such physical processes as the formation of a vortex from a meander of a frontal current, the vortex motion due to the β-effect, the non-frictional decay of a vortex, and the merging of two vortices. The numerical simulations display...

The strong nonlinear interaction between an intense vortex and the surrounding flow on a rotating sphere is considered. Owing to the background gradient of the potential vorticity around a monopolar vortex, a secondary current develops. This current is described using a cylindrical coordinate frame translated with the vortex center. The vortex moti...

A new class of stationarily translating monopolar Rossby solitons (anticyclones) in a rotating shallow fluid is studied both experimentally and theoretically. Unlike the KdV solitons, the two-dimensional monopolar solitons are found to have trapped fluid which is transported westward at the phase speed. These dualistic structures appear to be vorti...

The evolution of an initially circular vortex is considered in terms of the relation between its dimensions and the screening scale — the radius of deformation of the quasigeostrophic single-layer model in the betaplane. It is shown that the beta-effect causes the displacement of the center of the vortex as a result of wave drift and secondary flow...

The evolution of cyclones and anticyclones with a characteristic scale substantially exceeding the radius of deformation is investigated numerically. An equation obtained by an asymptotic method for small values of the Kibel'-Rossby number is employed. The model ensures conservation of the potential vorticity in the fluid particles for motions of f...

Synoptic motions in the atmosphere and ocean are studied on the basis of a method for the filtering of inertial-gravity waves. This method makes it possible to reduce the problem to one of calculating the evolution of an absolute eddy and total pressure (the sum of static and dynamic pressures) as the conservation laws (both Lagrangian and integral...