Abstract
We investigate the dynamics of Jupiter’s upper troposphere and lower stratosphere using a General Circulation Model that includes two-stream radiation and optional heating from below. Based on the MITgcm dynamical core, this is a new generation of Oxford's Jupiter General Circulation Model [Zuchowski, L.C. et al., 2009. Plan. Space Sci., 57, 1525–1537, doi:10.1016/j.pss.2009.05.008]. We simulate Jupiter’s atmosphere at up to 0.7° horizontal resolution with 33 vertical levels down to a pressure of 18 bar, in configurations with and without a 5.7Wm−2 interior heat flux. Simulations ran for 130000–150000 d to allow the deep atmosphere to come into radiative equilibrium. Baroclinic instability generates alternating, eddy-driven, midlatitude jets in both cases. With interior heating the zonal jets migrate towards the equator and become barotropically unstable. This generates Rossby waves that radiate away from the equator, depositing westerly momentum there via eddy angular momentum flux convergence and spinning up a super-rotating 20ms−1 equatorial jet throughout the troposphere. There are 30–35 zonal jets with latitudinal separation comparable with the real planet, and there is strong eddy activity throughout. Without interior heating the jets do not migrate and a divergent eddy angular momentum flux at the equator spins up a broad, 50ms−1 sub-rotating equatorial jet with weak eddy activity at low latitudes.
Highlights
Despite more than 40 years of investigation by space-borne instrumentation, the nature of the atmospheric circulation of the Solar System’s giant planets remains one of the most enigmatic problems in planetary atmospheric science
Using more sophisticated General Circulation Models (GCMs), various groups have investigated the relative importance of effects such as interior heat fluxes, differential radiative forcing, and latent heat release on the formation of zonal jets (Williams, 2003b; Lian and Showman, 2008; Schneider and Liu, 2009; Liu and Schneider, 2010; Lian and Showman, 2010; Liu and Schneider, 2011; Medvedev et al, 2013)
It is a major update of the Jupiter version of the Oxford Planetary Unified (Model) System (OPUS), as used by Zuchowski et al (2009a), which was a limited area model based on the dynamical core of the Met-Office External Unified Model (ExtUM) v4.5
Summary
Despite more than 40 years of investigation by space-borne instrumentation, the nature of the atmospheric circulation of the Solar System’s giant planets remains one of the most enigmatic problems in planetary atmospheric science. Using more sophisticated General Circulation Models (GCMs), various groups have investigated the relative importance of effects such as interior heat fluxes, differential radiative forcing, and latent heat release on the formation of zonal jets (Williams, 2003b; Lian and Showman, 2008; Schneider and Liu, 2009; Liu and Schneider, 2010; Lian and Showman, 2010; Liu and Schneider, 2011; Medvedev et al, 2013) Various combinations of these effects have been able to produce flow fields qualitatively similar to observations in some cases. Appendix A contains full details of our Jupiter model parametrisations
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