Jovian atmospheric dynamics: an update afterGalileoandCassini

Abstract

The Galileo and Cassini spacecrafts have greatly enhanced the observational record of Jupiter's tropospheric dynamics, particularly through returning high spatial resolution, multi-spectral and global imaging data with episodic coverage over periods of months to years. These data, along with those from Earth-based telescopes, have revealed the stability of Jupiter's zonal jets, captured the evolution of vortices and equatorial waves, and mapped the distributions of lightning and moist convection. Because no observations of Jupiter's interior exist, a forward modelling approach has been used to relate observations at cloud level to models of shallow or deep jet structure, shallow or deep jet forcing and energy transfer between turbulence, vortices and jets. A range of observed phenomena can be reproduced in shallow models, though the Galileo probe winds and jet stability arguments hint at the presence of deep jets. Many deep models, however, fail to reproduce Jupiter-like non-zonal features (e.g. vortices). Jupiter's dynamics likely include both deep and shallow processes, requiring an integrated approach to future modelling-an important goal for the post-Galileo and Cassini era.

Brightness power spectral distribution and waves in Jupiter's upper cloud and hazes

“…This banded structure is correlated with a zonal circulation dominated by a system of jets, the zones corresponding to anticyclonic vorticity areas and belts to cyclonic vorticity regions (Ingersoll et al 2004;Vasavada and Showman 2005). A variety of dynamical phenomena inside the belt/zone structure is detected by their cloud patterns (waves, irregular storms, closed vortices, etc.).…”

Taylor–Proudman columns in non‐hydrostatic divergent baroclinic and barotropic flows

“…Note that these results describe three-dimensional flow fields where the direction of the rotation vector has a component along the northward direction e λ , because rotation is around the polar axis, not along the local vertical direction e r , defined by the direction of −g (Hide, 1969;Busse, 1976;de Verdière and Schopp, 1994;Tassoul, 2000;Vasavada and Showman, 2005;Gerkema et al, 2008, and references therein). Therefore k : def = e λ cos λ + e r sin λ, with λ being latitude.…”

“…The author is indebted to J-Y K. Cho for highlighting the Tassoul (2000) analysis and to A. Showman for pointing out the Vasavada & Showman (2005) discussion.…”

“…While it is standard practice to discuss the result for a rotation vector parallel to the vertical (Pedlosky, 1987;Tassoul, 2000), especially in the context of the Earth's atmosphere, both proofs are actually valid and rarely discussed with consideration to the fact that the rotation vector of any planet is parallel to the polar axis, not the local vertical (see e.g. Hide, 1969;Busse, 1976;Vasavada and Showman, 2005, using Pedlosky's formulation).…”

Geophysical fluid dynamics: whence, whither and why?

“…It is a beautiful simulation, full of jets and eddies. But it is nowhere close to the resolution needed to resolve the question as to the nature of Jupiter's jets, especially in the vertical, especially given the contrasting paradigms for jet maintenance that require very different types of numerical model to properly simulate them [49]. …”