Comparison of the deep atmospheric dynamics of Jupiter and Saturn in light of the Juno and Cassini gravity measurements

TL;DR

This paper reviews how gravity measurements from Juno and Cassini have advanced understanding of the vertical structure and controlling mechanisms of zonal jets on Jupiter and Saturn, revealing their depths and magnetic influences.

Contribution

It synthesizes recent gravity data to constrain the depth and magnetic interactions of planetary jets, providing new insights into gas giant atmospheric dynamics.

Findings

Jets extend 3000 km on Jupiter and 9000 km on Saturn below clouds.

Magnetic field likely influences jet damping at certain depths.

Gravity data constrains the vertical profiles of zonal flows.

Abstract

The nature and structure of the observed east-west flows on Jupiter and Saturn has been one of the longest-lasting mysteries in planetary science. This mystery has been recently unraveled due to the accurate gravity measurements provided by the Juno mission to Jupiter and the Grand Finale of the Cassini mission to Saturn. These two experiments, which coincidentally happened around the same time, allowed determination of the vertical and meridional profiles of the zonal flows on both planets. This paper reviews the topic of zonal jets on the gas giants in light of the new data from these two experiments. The gravity measurements not only allow the depth of the jets to be constrained, yielding the inference that the jets extend roughly 3000 and 9000 km below the observed clouds on Jupiter and Saturn, respectively, but also provide insights into the mechanisms controlling these zonal flows. Specifically, for both planets this depth corresponds to the depth where electrical conductivity is within an order of magnitude of 1 S/m, implying that the magnetic field likely plays a key role in damping the zonal flows.