Equatorial superrotation in shallow atmospheres

Simple, shallow‐water models have been successful in reproducing two key observables in the atmospheres of the giant planets: the formation of robust, and fully turbulent, latitudinal jets and the decrease of the zonal wind amplitude with latitude. However, they have to date consistently failed in reproducing the strong prograde (superrotating) equatorial winds that are often observed on such planets. In this paper we show that shallow water models not only can give rise to superrotating winds, but can do so very robustly, provided that the physical process of large‐scale energy dissipation by radiative relaxation is taken into account. When energy is removed by linear friction, equatorial superrotation does not develop; when energy is removed by radiative relaxation, superrotation develops at apparently any deformation radius.

[1]  T. Schneider,et al.  Formation of Jets and Equatorial Superrotation on Jupiter , 2008, 0809.4302.

[2]  R. K. Scott,et al.  A Barotropic Model of the Angular Momentum–Conserving Potential Vorticity Staircase in Spherical Geometry , 2008 .

[3]  M. McIntyre,et al.  Multiple Jets as PV Staircases: The Phillips Effect and the Resilience of Eddy-Transport Barriers , 2008 .

[4]  A. Showman.  Numerical Simulations of Forced Shallow-Water Turbulence: Effects of Moist Convection on the Large-Scale Circulation of Jupiter and Saturn , 2007 .

[5]  R. K. Scott,et al.  Forced-dissipative shallow water turbulence on the sphere , 2006 .

[6]  P. Read,et al.  Hadley circulations and Kelvin wave-driven equatorial jets in the atmospheres of Jupiter and Saturn , 2005 .

[7]  J. Theiss.  Equatorward Energy Cascade, Critical Latitude, and the Predominance of Cyclonic Vortices in Geostrophic Turbulence , 2004 .

[8]  A. Ingersoll,et al.  A high‐resolution, three‐dimensional model of Jupiter's Great Red Spot , 2001 .

[9]  D. Dritschel,et al.  A numerical investigation of the stability of isolated shallow water vortices , 2000 .

[10]  T. Guillot.  Interiors of giant planets inside and outside the solar system. , 1999, Science.

[11]  C. Ronchi,et al.  Spontaneous formation of equatorial jets in freely decaying shallow water turbulence , 1999 .

[12]  L. Polvani,et al.  The Morphogenesis of Bands and Zonal Winds in the Atmospheres on the Giant Outer Planets , 1996, Science.

[13]  L. Polvani,et al.  The emergence of jets and vortices in freely evolving, shallow-water turbulence on a sphere , 1996 .

[14]  L. Polvani,et al.  The coherent structures of shallow-water turbulence: Deformation-radius effects, cyclone/anticyclone asymmetry and gravity-wave generation. , 1994, Chaos.

[15]  S. Yoden,et al.  A numerical experiment on two-dimensional decaying turbulence on a rotating sphere , 1993 .

[16]  M. Maltrud,et al.  Energy spectra and coherent structures in forced two-dimensional and beta-plane turbulence , 1991, Journal of Fluid Mechanics.

[17]  R. Garcia.  On the Mean Meridional Circulation of the Middle Atmosphere , 1987 .

[18]  Gareth P. Williams.  Planetary Circulations: 1. Barotropic Representation of Jovian and Terrestrial Turbulence , 1978 .

[19]  D. Andrews,et al.  Planetary Waves in Horizontal and Vertical Shear: Asymptotic Theory for Equatorial Waves in Weak Shear , 1976 .

[20]  F. Busse.  A simple model of convection in the Jovian atmosphere , 1976 .

[21]  P. Rhines.  Waves and turbulence on a beta-plane , 1975, Journal of Fluid Mechanics.

[22]  A. Vasavada,et al.  Dynamics of Jupiter's Atmosphere , 1998 .

[23]  Philip S. Marcus,et al.  Jupiter's Great Red Spot and Other Vortices , 1993 .

[24]  M. McIntyre.  How Well do we Understand the Dynamics of Stratospheric Warmings , 1982 .