Pub Date : 2020-08-05DOI: 10.1080/03091929.2020.1797712
Xing Wei
We apply Laplace's tidal theory to the evolution of lunar and solar tides on the geologic timescale of Earth's rotation and study the tidal resonance. We study the global tide in the mid-ocean far away from continents. On the short timescale, a linear relationship of tidal height and Earth's rotation is obtained. On the long timescale, the tide is less than 1 metre at present but it was 5 metres in the past and will reach 8 metres in the future because of resonances of tidal wave and Earth's rotation. We conclude that the Earth–Moon orbital separation and the slowdown of Earth's rotation are faster than expected before.
{"title":"On the evolution of global ocean tides","authors":"Xing Wei","doi":"10.1080/03091929.2020.1797712","DOIUrl":"https://doi.org/10.1080/03091929.2020.1797712","url":null,"abstract":"We apply Laplace's tidal theory to the evolution of lunar and solar tides on the geologic timescale of Earth's rotation and study the tidal resonance. We study the global tide in the mid-ocean far away from continents. On the short timescale, a linear relationship of tidal height and Earth's rotation is obtained. On the long timescale, the tide is less than 1 metre at present but it was 5 metres in the past and will reach 8 metres in the future because of resonances of tidal wave and Earth's rotation. We conclude that the Earth–Moon orbital separation and the slowdown of Earth's rotation are faster than expected before.","PeriodicalId":56132,"journal":{"name":"Geophysical and Astrophysical Fluid Dynamics","volume":"22 1","pages":"184 - 191"},"PeriodicalIF":1.3,"publicationDate":"2020-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82422528","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-07-27DOI: 10.1080/03091929.2020.1791844
K. Lam, D. Kong, Keke Zhang
We report a new nonlinear phenomenon discovered in the classical problem of thermal convection in a rapidly rotating, self-gravitating, internally heated fluid sphere that also undergoes weak precession. When the Prandtl number of fluids is sufficiently large, convection-driven columnar rolls – which are nearly geostrophic and marked by small azimuthal scale – cannot have substantial nonlinear interaction with precession-driven flow that is in the form of an equatorially antisymmetric, large-scale inertial wave in the mantle frame of reference. When the Prandtl number of fluids is sufficiently small, convection-driven flow, because of predominant inertial effects in its dynamics, is non-geostrophic and in the form of an equatorially symmetric, large-scale inertial wave, and, hence, is able to interact destructively with the precession-driven large-scale inertial wave via nonlinear effects. We reveal that the destructive interaction between the convection-driven wave and the precession-driven wave leads to a localised convective wave that is nearly equatorially symmetric, progradely travelling in the azimuthal direction, and largely confined within a quarter of the sphere.
{"title":"Localised thermal convection in rotating spheres that undergo weak precession","authors":"K. Lam, D. Kong, Keke Zhang","doi":"10.1080/03091929.2020.1791844","DOIUrl":"https://doi.org/10.1080/03091929.2020.1791844","url":null,"abstract":"We report a new nonlinear phenomenon discovered in the classical problem of thermal convection in a rapidly rotating, self-gravitating, internally heated fluid sphere that also undergoes weak precession. When the Prandtl number of fluids is sufficiently large, convection-driven columnar rolls – which are nearly geostrophic and marked by small azimuthal scale – cannot have substantial nonlinear interaction with precession-driven flow that is in the form of an equatorially antisymmetric, large-scale inertial wave in the mantle frame of reference. When the Prandtl number of fluids is sufficiently small, convection-driven flow, because of predominant inertial effects in its dynamics, is non-geostrophic and in the form of an equatorially symmetric, large-scale inertial wave, and, hence, is able to interact destructively with the precession-driven large-scale inertial wave via nonlinear effects. We reveal that the destructive interaction between the convection-driven wave and the precession-driven wave leads to a localised convective wave that is nearly equatorially symmetric, progradely travelling in the azimuthal direction, and largely confined within a quarter of the sphere.","PeriodicalId":56132,"journal":{"name":"Geophysical and Astrophysical Fluid Dynamics","volume":"18 1","pages":"280 - 296"},"PeriodicalIF":1.3,"publicationDate":"2020-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74483649","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-07-17DOI: 10.1080/03091929.2020.1788013
B. H. Burgess
The evolution of thin frontal jets in large-scale shallow water quasigeostrophic flow is studied, with a focus on jet curvature and arclength. The flow is large-scale in the sense that mixed regions of potential vorticity (PV) are much larger than the deformation length . However the presence of sharp PV fronts with widths drives the ongoing growth of the flow's length scale; in particular the PV fronts and collocated jets support long undulations that facilitate jet interactions and the merger of mixed regions. The flow develops large dynamically active multilevel vortices containing two main mixed levels of PV, as well as small dynamically inactive vortices that persist for long times; these regions and their frontal jets display markedly different scaling properties. The frontal jets bounding the large dynamically active mixed regions follow power laws consistent with the scaling symmetries of the modified Korteweg-de Vries (mKdV) equation, which governs the motion of the jet axis in the thin-jet limit. These jets have population total arc length decaying approximately as , average arc length growing like , rms curvature as and typical curvature fluctuation as .
{"title":"Thin-jet scaling in large-scale shallow water quasigeostrophic flow","authors":"B. H. Burgess","doi":"10.1080/03091929.2020.1788013","DOIUrl":"https://doi.org/10.1080/03091929.2020.1788013","url":null,"abstract":"The evolution of thin frontal jets in large-scale shallow water quasigeostrophic flow is studied, with a focus on jet curvature and arclength. The flow is large-scale in the sense that mixed regions of potential vorticity (PV) are much larger than the deformation length . However the presence of sharp PV fronts with widths drives the ongoing growth of the flow's length scale; in particular the PV fronts and collocated jets support long undulations that facilitate jet interactions and the merger of mixed regions. The flow develops large dynamically active multilevel vortices containing two main mixed levels of PV, as well as small dynamically inactive vortices that persist for long times; these regions and their frontal jets display markedly different scaling properties. The frontal jets bounding the large dynamically active mixed regions follow power laws consistent with the scaling symmetries of the modified Korteweg-de Vries (mKdV) equation, which governs the motion of the jet axis in the thin-jet limit. These jets have population total arc length decaying approximately as , average arc length growing like , rms curvature as and typical curvature fluctuation as .","PeriodicalId":56132,"journal":{"name":"Geophysical and Astrophysical Fluid Dynamics","volume":"67 1","pages":"481 - 503"},"PeriodicalIF":1.3,"publicationDate":"2020-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86634813","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-07-09DOI: 10.1080/03091929.2020.1786551
D. Stepanov, E. Ryzhov, P. Berloff, K. Koshel
ABSTRACT Clustering of tracers floating on the ocean surface and evolving due to combined velocity fields consisting of a deterministic mesoscale component and a kinematic random component is analysed. The random component represents the influence of submesoscale motions. A theory of exponential clustering in random velocity fields is applied to characterise the obtained clustering scenarios in both steady and unsteady time-dependent mesoscale flows, as simulated by a comprehensive realistic, eddy-resolving, general circulation model for the Japan/East Sea. The mesoscale flow field abounds in transient eddy-like patterns modulating and branching the main currents, and the underlying time-mean flow component features closed recirculation zones that can entrap the tracer. The submesoscale flow component is modelled kinematically, as a divergent random velocity field with a prescribed correlation radius and variance. The combined flow induces tracer clustering, that is, the exponential growth of tracer density in patches with vanishing areas. The statistical topography methodology, which provides integral characteristics to quantify the emerging clusters, uncovers drastic dependence of the clustering rates on whether the mesoscale flow component is taken to be steady or time-dependent. The former situation favours robust exponential clustering, similar to the theoretically understood case of purely divergent and zero-mean random velocity. The latter situation, on the contrary, hinders exponential clustering due to significant advection of the tracer out of the nearly enclosed eddies, at the rate faster than the clustering rate.
{"title":"Floating tracer clustering in divergent random flows modulated by an unsteady mesoscale ocean field","authors":"D. Stepanov, E. Ryzhov, P. Berloff, K. Koshel","doi":"10.1080/03091929.2020.1786551","DOIUrl":"https://doi.org/10.1080/03091929.2020.1786551","url":null,"abstract":"ABSTRACT Clustering of tracers floating on the ocean surface and evolving due to combined velocity fields consisting of a deterministic mesoscale component and a kinematic random component is analysed. The random component represents the influence of submesoscale motions. A theory of exponential clustering in random velocity fields is applied to characterise the obtained clustering scenarios in both steady and unsteady time-dependent mesoscale flows, as simulated by a comprehensive realistic, eddy-resolving, general circulation model for the Japan/East Sea. The mesoscale flow field abounds in transient eddy-like patterns modulating and branching the main currents, and the underlying time-mean flow component features closed recirculation zones that can entrap the tracer. The submesoscale flow component is modelled kinematically, as a divergent random velocity field with a prescribed correlation radius and variance. The combined flow induces tracer clustering, that is, the exponential growth of tracer density in patches with vanishing areas. The statistical topography methodology, which provides integral characteristics to quantify the emerging clusters, uncovers drastic dependence of the clustering rates on whether the mesoscale flow component is taken to be steady or time-dependent. The former situation favours robust exponential clustering, similar to the theoretically understood case of purely divergent and zero-mean random velocity. The latter situation, on the contrary, hinders exponential clustering due to significant advection of the tracer out of the nearly enclosed eddies, at the rate faster than the clustering rate.","PeriodicalId":56132,"journal":{"name":"Geophysical and Astrophysical Fluid Dynamics","volume":"106 1","pages":"690 - 714"},"PeriodicalIF":1.3,"publicationDate":"2020-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87987969","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-06-22DOI: 10.1080/03091929.2020.1777549
Abrar A. Ali, L. Silvers
The linear equations of thermal convection in a compressible fluid with non-constant transport coefficients are derived. The criterion for the onset of convection is established, based on linear stability analysis, for a range of different temperature-dependent profiles of thermal conductivity and viscosity. Temperature-dependent transport coefficients are shown to lead to a more complex behaviour than their constant counterparts, and modifies the stability condition of the fluid. When the Rayleigh number is defined in terms of the mid-layer physical properties and the temperature gradient at the top is held constant, increasing the temperature-dependence of thermal conductivity is found to raise the critical Rayleigh number dramatically, as the convective disturbance is then concentrated mainly at the top of the layer. In contrast, for viscosity a more subtle effect on stability is identified.
{"title":"The effect of temperature-dependent viscosity and thermal conductivity on the onset of compressible convection","authors":"Abrar A. Ali, L. Silvers","doi":"10.1080/03091929.2020.1777549","DOIUrl":"https://doi.org/10.1080/03091929.2020.1777549","url":null,"abstract":"The linear equations of thermal convection in a compressible fluid with non-constant transport coefficients are derived. The criterion for the onset of convection is established, based on linear stability analysis, for a range of different temperature-dependent profiles of thermal conductivity and viscosity. Temperature-dependent transport coefficients are shown to lead to a more complex behaviour than their constant counterparts, and modifies the stability condition of the fluid. When the Rayleigh number is defined in terms of the mid-layer physical properties and the temperature gradient at the top is held constant, increasing the temperature-dependence of thermal conductivity is found to raise the critical Rayleigh number dramatically, as the convective disturbance is then concentrated mainly at the top of the layer. In contrast, for viscosity a more subtle effect on stability is identified.","PeriodicalId":56132,"journal":{"name":"Geophysical and Astrophysical Fluid Dynamics","volume":"20 1","pages":"207 - 220"},"PeriodicalIF":1.3,"publicationDate":"2020-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87419838","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-06-15DOI: 10.1080/03091929.2020.1772779
Charly de Marez, T. Meunier, Pauline Tedesco, P. L’Hégaret, X. Carton
ABSTRACT In this paper, we investigate the vortex–wall interaction on the β-plane, using a submesoscale and internal waves resolving model in an idealised context. Our results bring new insights on the dynamics of oceanic mesoscale eddies as they drift toward a western boundary. We show that there exists a strong cyclone/anticyclone asymmetry in the interaction, contrary to what was suggested in previous studies: anticyclones cannot drift meridionally along the wall because of internal Kelvin Waves–current interactions. This interaction is shown to be an efficient mechanism to generate small coherent submesoscale cyclones, which can travel hundreds of kilometres into the interior of the ocean.
{"title":"Vortex–wall interaction on the β-plane and the generation of deep submesoscale cyclones by internal Kelvin Waves–current interactions","authors":"Charly de Marez, T. Meunier, Pauline Tedesco, P. L’Hégaret, X. Carton","doi":"10.1080/03091929.2020.1772779","DOIUrl":"https://doi.org/10.1080/03091929.2020.1772779","url":null,"abstract":"ABSTRACT In this paper, we investigate the vortex–wall interaction on the β-plane, using a submesoscale and internal waves resolving model in an idealised context. Our results bring new insights on the dynamics of oceanic mesoscale eddies as they drift toward a western boundary. We show that there exists a strong cyclone/anticyclone asymmetry in the interaction, contrary to what was suggested in previous studies: anticyclones cannot drift meridionally along the wall because of internal Kelvin Waves–current interactions. This interaction is shown to be an efficient mechanism to generate small coherent submesoscale cyclones, which can travel hundreds of kilometres into the interior of the ocean.","PeriodicalId":56132,"journal":{"name":"Geophysical and Astrophysical Fluid Dynamics","volume":"48 1","pages":"588 - 606"},"PeriodicalIF":1.3,"publicationDate":"2020-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84976269","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-06-15DOI: 10.1080/03091929.2020.1774876
A. Kurganov, Yongle Liu, V. Zeitlin
ABSTRACT We introduce a new high-resolution well-balanced central-upwind scheme for two-dimensional rotating shallow water equations with horizontal temperature/density gradients – thermal rotating shallow water equations. The scheme maintains the equilibrium states in the presence of topography and temperature/density variations, and allows for high-resolution tracking of the active scalar field together with velocity and pressure fields. We use the new scheme to highlight both the similarities and differences in the predictions of the thermal and isothermal shallow water models for the fundamental dynamical processes: evolution of isolated vortices in the midlatitude β-plane in the presence of topography and relaxation of localised pressure and temperature perturbations in the equatorial β-plane.
{"title":"Thermal versus isothermal rotating shallow water equations: comparison of dynamical processes by simulations with a novel well-balanced central-upwind scheme","authors":"A. Kurganov, Yongle Liu, V. Zeitlin","doi":"10.1080/03091929.2020.1774876","DOIUrl":"https://doi.org/10.1080/03091929.2020.1774876","url":null,"abstract":"ABSTRACT We introduce a new high-resolution well-balanced central-upwind scheme for two-dimensional rotating shallow water equations with horizontal temperature/density gradients – thermal rotating shallow water equations. The scheme maintains the equilibrium states in the presence of topography and temperature/density variations, and allows for high-resolution tracking of the active scalar field together with velocity and pressure fields. We use the new scheme to highlight both the similarities and differences in the predictions of the thermal and isothermal shallow water models for the fundamental dynamical processes: evolution of isolated vortices in the midlatitude β-plane in the presence of topography and relaxation of localised pressure and temperature perturbations in the equatorial β-plane.","PeriodicalId":56132,"journal":{"name":"Geophysical and Astrophysical Fluid Dynamics","volume":"68 1","pages":"125 - 154"},"PeriodicalIF":1.3,"publicationDate":"2020-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91363830","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-05-27DOI: 10.1080/03091929.2020.1762080
L. Ingel, A. A. Makosko
A theoretical problem on linear stationary disturbances introduced by spatial inhomogeneities of gravity field into the background geostrophic flow of the stratified rotating medium (atmosphere) is considered. For the first time, the three-dimensional analytical model is considered. Our results imply that inhomogeneities of the gravity field can lead to ordered perturbations of the velocity field of atmospheric currents in large areas. Our three-dimensional model allows us to understand and analyse some of the simplest mechanisms and patterns of generation of such disturbances and to make some estimates. The amplitude of the disturbances for the velocity horizontal components can reach values of the order of buoyancy frequency multiplied by the amplitude of deviations of the geoid. This result agrees with the estimates obtained previously for a substantially different disturbances mechanism caused by gravity field inhomogeneities.
{"title":"Geostrophic flow disturbances influenced by inhomogeneities of gravity field: 3D analytical model","authors":"L. Ingel, A. A. Makosko","doi":"10.1080/03091929.2020.1762080","DOIUrl":"https://doi.org/10.1080/03091929.2020.1762080","url":null,"abstract":"A theoretical problem on linear stationary disturbances introduced by spatial inhomogeneities of gravity field into the background geostrophic flow of the stratified rotating medium (atmosphere) is considered. For the first time, the three-dimensional analytical model is considered. Our results imply that inhomogeneities of the gravity field can lead to ordered perturbations of the velocity field of atmospheric currents in large areas. Our three-dimensional model allows us to understand and analyse some of the simplest mechanisms and patterns of generation of such disturbances and to make some estimates. The amplitude of the disturbances for the velocity horizontal components can reach values of the order of buoyancy frequency multiplied by the amplitude of deviations of the geoid. This result agrees with the estimates obtained previously for a substantially different disturbances mechanism caused by gravity field inhomogeneities.","PeriodicalId":56132,"journal":{"name":"Geophysical and Astrophysical Fluid Dynamics","volume":"65 1","pages":"35 - 43"},"PeriodicalIF":1.3,"publicationDate":"2020-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72820245","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-05-20DOI: 10.1080/03091929.2020.1755671
W. McKiver
ABSTRACT Here we examine the motion of an isolated ellipsoidal vortex in a rotating stratified fluid. We derive an analytical solution to a set of balanced equations at the next order to quasi-geostrophic theory, providing insights into geophysical vortices at finite Rossby number ε. This is achieved through the solution of a set of complicated Poisson equations. Though complicated, the analytical solution give rise to a velocity field that depends linearly on the spatial coordinates inside the vortex, and, thus preserves the ellipsoidal form. From this general solution, we determine a number of equilibria where the vortex rotates steadily about the vertical axis and examine their stability. At the next order to QG, one finds asymmetry in the behaviour of cyclonic and anti-cyclonic vortices, with anti-cyclonic vortices rotating faster and generally more unstable than cyclonic vortices.
{"title":"Balanced ellipsoidal vortex at finite Rossby number","authors":"W. McKiver","doi":"10.1080/03091929.2020.1755671","DOIUrl":"https://doi.org/10.1080/03091929.2020.1755671","url":null,"abstract":"ABSTRACT Here we examine the motion of an isolated ellipsoidal vortex in a rotating stratified fluid. We derive an analytical solution to a set of balanced equations at the next order to quasi-geostrophic theory, providing insights into geophysical vortices at finite Rossby number ε. This is achieved through the solution of a set of complicated Poisson equations. Though complicated, the analytical solution give rise to a velocity field that depends linearly on the spatial coordinates inside the vortex, and, thus preserves the ellipsoidal form. From this general solution, we determine a number of equilibria where the vortex rotates steadily about the vertical axis and examine their stability. At the next order to QG, one finds asymmetry in the behaviour of cyclonic and anti-cyclonic vortices, with anti-cyclonic vortices rotating faster and generally more unstable than cyclonic vortices.","PeriodicalId":56132,"journal":{"name":"Geophysical and Astrophysical Fluid Dynamics","volume":"64 1","pages":"453 - 480"},"PeriodicalIF":1.3,"publicationDate":"2020-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80186579","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-05-13DOI: 10.1080/03091929.2020.1756283
M. Jalali, D. Dritschel
We examine the equilibrium forms, linear stability and nonlinear evolution of two patches having opposite-signed, uniform potential vorticity anomalies in a single-layer shallow-water flow, under the quasi-geostrophic approximation. We widely vary the vortex area ratio, the potential vorticity anomaly ratio, as well as the Rossby deformation length to unravel the full complexity of possible interactions in this system. Opposite-signed vortex interactions turn out to be far richer than their like-signed counterparts, comprehensively examined in a previous study (Jalali and Dritschel 2018, Geophys. Astrophys. Fluid Dyn. 2018, 112, 375). Unstable equilibria may evolve into a myriad of forms, many unsteady and aperiodic, and the original two vortex patches may break up into many patches which survive for long times, perhaps indefinitely.
{"title":"Stability and evolution of two opposite-signed quasi-geostrophic shallow-water vortex patches","authors":"M. Jalali, D. Dritschel","doi":"10.1080/03091929.2020.1756283","DOIUrl":"https://doi.org/10.1080/03091929.2020.1756283","url":null,"abstract":"We examine the equilibrium forms, linear stability and nonlinear evolution of two patches having opposite-signed, uniform potential vorticity anomalies in a single-layer shallow-water flow, under the quasi-geostrophic approximation. We widely vary the vortex area ratio, the potential vorticity anomaly ratio, as well as the Rossby deformation length to unravel the full complexity of possible interactions in this system. Opposite-signed vortex interactions turn out to be far richer than their like-signed counterparts, comprehensively examined in a previous study (Jalali and Dritschel 2018, Geophys. Astrophys. Fluid Dyn. 2018, 112, 375). Unstable equilibria may evolve into a myriad of forms, many unsteady and aperiodic, and the original two vortex patches may break up into many patches which survive for long times, perhaps indefinitely.","PeriodicalId":56132,"journal":{"name":"Geophysical and Astrophysical Fluid Dynamics","volume":"43 1","pages":"561 - 587"},"PeriodicalIF":1.3,"publicationDate":"2020-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80853926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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