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1. Introduction The banded organization of clouds and zonal winds in the atmospheres of the outer planets has long fascinated atmosphere and ocean dynamicists and planetologists, especially with regard to the stability and persistence of these patterns. This banded organization, mainly apparent in clouds thought to be of ammonia and NH 4 SH ice, is one of the most striking features of the atmosphere of Jupiter. The cloud bands are associated with multiple zonal jets of alternating sign with
1. Introduction The banded organization of clouds and zonal winds in the atmospheres of the outer planets has long fascinated atmosphere and ocean dynamicists and planetologists, especially with regard to the stability and persistence of these patterns. This banded organization, mainly apparent in clouds thought to be of ammonia and NH 4 SH ice, is one of the most striking features of the atmosphere of Jupiter. The cloud bands are associated with multiple zonal jets of alternating sign with
1. Introduction Chaotic flows in stratified, rotating fluid systems like planetary atmospheres and oceans are often called “turbulent.” However, in such systems there is no such thing as turbulence without waves, a point well brought out in the celebrated paper of Rhines (1975) . One way to appreciate the point is to note that such systems always have background gradients of potential vorticity (PV) and then consider the implications for the momentum and angular momentum budgets. As will be
1. Introduction Chaotic flows in stratified, rotating fluid systems like planetary atmospheres and oceans are often called “turbulent.” However, in such systems there is no such thing as turbulence without waves, a point well brought out in the celebrated paper of Rhines (1975) . One way to appreciate the point is to note that such systems always have background gradients of potential vorticity (PV) and then consider the implications for the momentum and angular momentum budgets. As will be
. , 2004 : A local model for planetary atmospheres forced by small-scale convection. J. Atmos. Sci. , 61 , 1420 – 1433 . Stamp , A. P. , and T. E. Dowling , 1993 : Jupiter’s winds and Arnol’d’s second stability theorem: Slowly moving waves and neutral stability. J. Geophys. Res. , 98 , 18847 – 18855 . Steinsaltz , D. , 1987 : Instability of baroclinic waves with bottom slope. J. Phys. Oceanogr. , 17 , 2343 – 2350 . Sun , Z-P. , G. Schubert , and G. A. Glatzmaier , 1993
. , 2004 : A local model for planetary atmospheres forced by small-scale convection. J. Atmos. Sci. , 61 , 1420 – 1433 . Stamp , A. P. , and T. E. Dowling , 1993 : Jupiter’s winds and Arnol’d’s second stability theorem: Slowly moving waves and neutral stability. J. Geophys. Res. , 98 , 18847 – 18855 . Steinsaltz , D. , 1987 : Instability of baroclinic waves with bottom slope. J. Phys. Oceanogr. , 17 , 2343 – 2350 . Sun , Z-P. , G. Schubert , and G. A. Glatzmaier , 1993
some of the key energy production and loss processes occurring in the cloud layers of giant planets. Acknowledgments I thank Peter Gierasch for hosting me at Cornell during several summer visits, Tim Dowling for discussions about EPIC, B. Galperin and J. Theiss for discussions about fluid mechanics, and Tony Del Genio and two anonymous referees for helpful reviews. This research was supported by NSF Planetary Astronomy Grant AST-0206269 and NASA Planetary Atmospheres Grant NNG06GF28G. REFERENCES
some of the key energy production and loss processes occurring in the cloud layers of giant planets. Acknowledgments I thank Peter Gierasch for hosting me at Cornell during several summer visits, Tim Dowling for discussions about EPIC, B. Galperin and J. Theiss for discussions about fluid mechanics, and Tony Del Genio and two anonymous referees for helpful reviews. This research was supported by NSF Planetary Astronomy Grant AST-0206269 and NASA Planetary Atmospheres Grant NNG06GF28G. REFERENCES
1. Introduction This paper considers nonlinear dynamics of an idealized winter polar vortex in the Southern Hemisphere (SH) stratosphere with a barotropic model on a spherical domain. The SH polar vortex is stronger and less disturbed compared to that of the Northern Hemisphere. In other words, the zonal-mean zonal flow is stronger and planetary waves are weaker in the SH due to weaker forcing of the planetary waves in the troposphere. As a result, a major stratospheric sudden warming event had
1. Introduction This paper considers nonlinear dynamics of an idealized winter polar vortex in the Southern Hemisphere (SH) stratosphere with a barotropic model on a spherical domain. The SH polar vortex is stronger and less disturbed compared to that of the Northern Hemisphere. In other words, the zonal-mean zonal flow is stronger and planetary waves are weaker in the SH due to weaker forcing of the planetary waves in the troposphere. As a result, a major stratospheric sudden warming event had
-scale zonal jet. J. Fluid Mech. , 183 , 467 – 509 . Smith , K. S. , 2004 : A local model for planetary atmospheres forced by small-scale convection. J. Atmos. Sci. , 61 , 1420 – 1433 . Sukoriansky , S. , B. Galperin , and N. Dikovskaya , 2002 : Universal spectrum of two-dimensional turbulence on a rotating sphere and some basic features of atmospheric circulation on giant planets. Phys. Rev. Lett. , 89 . doi:10.1103/PhysRevLett.89. 124501 . Takehiro , S. , and Y-Y. Hayashi
-scale zonal jet. J. Fluid Mech. , 183 , 467 – 509 . Smith , K. S. , 2004 : A local model for planetary atmospheres forced by small-scale convection. J. Atmos. Sci. , 61 , 1420 – 1433 . Sukoriansky , S. , B. Galperin , and N. Dikovskaya , 2002 : Universal spectrum of two-dimensional turbulence on a rotating sphere and some basic features of atmospheric circulation on giant planets. Phys. Rev. Lett. , 89 . doi:10.1103/PhysRevLett.89. 124501 . Takehiro , S. , and Y-Y. Hayashi
of jets at equilibrium (e.g., Danilov and Gurarie 2002 , 2004 ; Smith 2004 ; Sukoriansky et al. 2007 ). The β -plane approximation has limited application to planetary atmospheres because of order one variations of Coriolis parameter with latitude, ϕ . On the sphere, both β and L D increase as ϕ → 0 and decrease as ϕ → π /2. Specifically, we have β = 2Ωcos ϕ and L D = ( gH ) 1/2 /2Ωsin ϕ . A local application of the planar expression in (3) indicates that, for small enough
of jets at equilibrium (e.g., Danilov and Gurarie 2002 , 2004 ; Smith 2004 ; Sukoriansky et al. 2007 ). The β -plane approximation has limited application to planetary atmospheres because of order one variations of Coriolis parameter with latitude, ϕ . On the sphere, both β and L D increase as ϕ → 0 and decrease as ϕ → π /2. Specifically, we have β = 2Ωcos ϕ and L D = ( gH ) 1/2 /2Ωsin ϕ . A local application of the planar expression in (3) indicates that, for small enough
traditional methods in that we have concentrated on a diagnosis of the energy associated with the forcing waves instead of analyzing Eliassen–Palm fluxes. Another difference from previous studies relates to the fact that instead of being restricted to the extratropical subdomain, our analysis is applied to the whole atmosphere, and the relevant circulation components are selected by means of projections onto 3D global functions that allow partitioning the atmospheric (global) circulation into planetary
traditional methods in that we have concentrated on a diagnosis of the energy associated with the forcing waves instead of analyzing Eliassen–Palm fluxes. Another difference from previous studies relates to the fact that instead of being restricted to the extratropical subdomain, our analysis is applied to the whole atmosphere, and the relevant circulation components are selected by means of projections onto 3D global functions that allow partitioning the atmospheric (global) circulation into planetary
zonal-average residual momentum balance in the two fluids that can be written as Integrate from the surface, where τ = τ s and τ e = 0, across the planetary boundary layers of the two fluids to where τ = 0, neglecting Reynolds stress processes in both fluids, we obtain the following: Adding the two together we find where Ψ A res = ρ A ψ A res and Ψ O res = ρ O ψ O res are the mass transports in the two fluids. We now consider two limit cases. In the mid–high-latitude atmosphere, the
zonal-average residual momentum balance in the two fluids that can be written as Integrate from the surface, where τ = τ s and τ e = 0, across the planetary boundary layers of the two fluids to where τ = 0, neglecting Reynolds stress processes in both fluids, we obtain the following: Adding the two together we find where Ψ A res = ρ A ψ A res and Ψ O res = ρ O ψ O res are the mass transports in the two fluids. We now consider two limit cases. In the mid–high-latitude atmosphere, the
winter terminates with a relatively rapid breakdown of the polar vortex known as the stratospheric final warming (SFW), marking the final transition from westerlies to easterlies in the extratropical stratosphere. There is considerable interannual variability in the timing of SFW events ( Waugh and Rong 2002 ) since they are sensitive to the preexisting stratospheric flow structure and variations in the upward propagation of tropospheric planetary waves ( Waugh et al. 1999 ). SFW events are more
winter terminates with a relatively rapid breakdown of the polar vortex known as the stratospheric final warming (SFW), marking the final transition from westerlies to easterlies in the extratropical stratosphere. There is considerable interannual variability in the timing of SFW events ( Waugh and Rong 2002 ) since they are sensitive to the preexisting stratospheric flow structure and variations in the upward propagation of tropospheric planetary waves ( Waugh et al. 1999 ). SFW events are more
