Remote determination of the shape of Jupiter’s vortices from laboratory experiments

Abstract

Jupiter’s dynamics shapes its cloud patterns but remains largely unknown below this natural observational barrier. Unraveling the underlying three-dimensional flows is thus a primary goal for NASA’s ongoing Juno mission that was launched in 2011. Here, we address the dynamics of large Jovian vortices using laboratory experiments complemented by theoretical and numerical analyses. We determine the generic force balance responsible for their three-dimensional pancake-like shape. From this, we define scaling laws for their horizontal and vertical aspect ratios as a function of the ambient rotation, stratification and zonal wind velocity. For the Great Red Spot in particular, our predicted horizontal dimensions agree well with measurements at the cloud level since the Voyager mission in 1979. We additionally predict the Great Red Spot’s thickness, inaccessible to direct observation: it has surprisingly remained constant despite the observed horizontal shrinking. Our results now await comparison with upcoming Juno observations.

Balanced ellipsoidal vortex equilibria in a background shear flow at finite Rossby number

“…These previous studies all point to the fact that the most resilient anticyclonic vortices must adopt a more oblate shape to resist the impact of vertical shear, while cyclonic vortices must reduce the impact of strain by in turn reducing their mean horizontal radius, becoming more prolate, as is found in this work. These findings also agree qualitatively with other theoretical and modelling studies (Hassanzadeh, Marcus & Le Gal 2012;Damien et al 2017;Lemasquerier et al 2020;Xu et al 2020) and observations of subsurface vortices (Bosse et al 2016;Dilmahamod et al 2018). Further observational studies would be needed to comprehensively catalogue the typical size, shape and orientation of subsurface cyclonic and anticyclonic eddies.…”

“…2006) and may even have relevance for the typical structure found for extraplanetary vortices (Abrahamyan 2016; Lemasquerier et al. 2020; Sánchez-Lavega et al. 2021).…”

“…Although, overall, these values of f /N are large, they are still within the values for which the flow is statically stable, based on the empirical formula found by Dritschel & McKiver (2015) from their study of turbulence simulations at different values of the Rossby and Prandtl ratio. This effect, along with the fact that oblate vortices tend to be anticyclonic, may lead to the overall dominance of anticyclonic eddies in geophysical flows (Graves et al 2006) and may even have relevance for the typical structure found for extraplanetary vortices (Abrahamyan 2016;Lemasquerier et al 2020;Sánchez-Lavega et al 2021).…”

“…2017; Lemasquerier et al. 2020; Xu et al. 2020) and observations of subsurface vortices (Bosse et al.…”

Jupiter’s Great Red Spot: Strong Interactions With Incoming Anticyclones in 2019

“…In recent anticyclone modeling and laboratory work, Lemasquerier et al. (2020) deduced that the GRS would have a depth of 150 km +104 ‐56 km, less than indicated above. This determination strongly depends on the stratification N , as Equation requires N = 0.01 s −1 to get 150 km.…”