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The Emergence of Multiple Robust Zonal Jets from Freely Evolving, Three-Dimensional Stratified Geostrophic Turbulence with Applications to Jupiter

Sayanagi, Kunio M. and Showman, Adam P. and Dowling, Timothy E. (2008) The Emergence of Multiple Robust Zonal Jets from Freely Evolving, Three-Dimensional Stratified Geostrophic Turbulence with Applications to Jupiter. Journal of the Atmospheric Sciences, 65 (12). pp. 3947-3962. ISSN 0022-4928. https://resolver.caltech.edu/CaltechAUTHORS:SAYjas08

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Abstract

Three-dimensional numerical simulations of freely evolving stratified geostrophic turbulence on the β plane are presented as a simplified model of zonal jet formation on Jupiter. This study samples the parameter space that covers the low, middle, and high latitudes of Jupiter by varying the central latitude of the β plane. The results show that robust zonal jets can emerge from initial small-scale random turbulence through the upscale redistribution of the kinetic energy in the spectral space. The resulting flow’s sensitivities to the flow’s deformation radius LD and the two-dimensional Rhines length Lβ = (U/β)^½ (U is the characteristic turbulence velocity and β is the meridional gradient of the planetary vorticity) are tested, revealing that whether the outcome of the upscale energy transfer becomes dominated by jets or vortices depends on the relative values of LD and Lβ. The values of Lβ and LD are varied by tuning the β-plane parameters, and it is found that the flow transitions from a jet-dominated regime in Lβ ≲ LD to a vortical flow in Lβ ≳ LD. A height-to-width ratio equal to f/N, the Coriolis parameter divided by the Brunt–Väisälä frequency, has previously been established for stable vortices, and this paper shows that this aspect ratio also applies to the zonal jets that emerge in these simulations.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1175/2008JAS2558.1DOIUNSPECIFIED
Additional Information:© 2008 American Meteorological Society. (Manuscript received 6 July 2007, in final form 3 June 2008) KMS acknowledges useful inputs from Boris Galperin, Peter Read, Hiro Yamazaki, and Shi-geo Yoden. The authors thank constructive comments by two anonymous reviewers. The study was supported by NASA Planetary Atmospheres Grants NNG06GF28G (to APS) and NNG05GO06G (to TED).
Funders:
Funding AgencyGrant Number
NASANNG06GF28G
NASANNG05GO06G
Issue or Number:12
Record Number:CaltechAUTHORS:SAYjas08
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:SAYjas08
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:13054
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:17 Jan 2009 00:12
Last Modified:03 Oct 2019 00:34

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