Turbulent Deep Convection at low Rossby Number: A Model for Zonal Flow and Thermal Emissions of Jupiter and Saturn
Abstract
We use numerical models to show that deep convection can result in the observed surface fluid flow and thermal emission patterns of Jupiter and Saturn. The simulations of Boussinesq convection in a spherical shell are dynamically self-consistent and generate large-scale zonal jets that interact with thermal plumes to produce the surface heat flow pattern. The surface fluid flow is dominantly zonal with a prograde equatorial jet and multiple alternating jets at higher latitudes. The zonal jet widths in our numerical models, and of Jupiter and Saturn, follow Rhines scaling. The scaling for zonal flow in a spherical shell is distinguished from that in a full sphere or a shallow layer by the effect of the tangent cylinder, which marks a reversal in the sign of the planetary β - parameter and a jump in the Rhines length. This jump is present in the numerical simulations as a sharp equator-ward increase in jet widths - a transition that is also apparent on Jupiter and Saturn. Our models generate a surface heat flow pattern with a broad minimum at the equator and peaks at the poles. The zonal jets modulate this pattern at smaller latitudinal scales. Superposing the model heat flow pattern with incoming solar radiation results in global heat flow that, similar to Jupiter and Saturn, is roughly constant in latitude. Our results support the hypothesis that the large-scale patterns of heat and zonal flow originate deep within the molecular hydrogen envelopes of the giant planets.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2007
- Bibcode:
- 2007AGUFM.P23C..03H
- Keywords:
-
- 1507 Core processes (1213;
- 8115);
- 3314 Convective processes;
- 3367 Theoretical modeling;
- 5704 Atmospheres (0343;
- 1060);
- 5724 Interiors (8147)