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Icarus 187 (2007) 540557 www.elsevier.com/locate/icarus

Summary: Icarus 187 (2007) 540557
Turbulent convection in rapidly rotating spherical shells:
A model for equatorial and high latitude jets on Jupiter and Saturn
Moritz Heimpel a,
, Jonathan Aurnou b
a Department of Physics, University of Alberta, Edmonton, Alberta, Canada T6G 2J1
b Department of Earth and Space Sciences, University of California, Los Angeles, CA 90095-1567, USA
Received 1 October 2005; revised 13 October 2006
Available online 15 December 2006
The origin of zonal jets on the jovian planets has long been a topic of scientific debate. In this paper we show that deep convection in a spherical
shell can generate zonal flow comparable to that observed on Jupiter and Saturn, including a broad prograde equatorial jet and multiple alternating
jets at higher latitudes. We present fully turbulent, 3D spherical numerical simulations of rapidly rotating convection with different spherical shell
geometries. The resulting global flow fields tend to be segregated into three regions (north, equatorial, and south), bounded by the tangent cylinder
that circumscribes the inner boundary equator. In all of our simulations a strong prograde equatorial jet forms outside the tangent cylinder, whereas
multiple jets form in the northern and southern hemispheres, inside the tangent cylinder. The jet scaling of our numerical models and of Jupiter
and Saturn is consistent with the theory of geostrophic turbulence, which we extend to include the effect of spherical shell geometry. 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 -parameter and a jump in the Rhines length. This jump is manifest in the numerical simulations as a sharp equatorward


Source: Aurnou, Jonathan - Department of Earth and Space Sciences, University of California at Los Angeles


Collections: Geosciences