A Possible Mechanism to Explain the Prograde Equatorial Jet of a Jupiter-like Gaseous Giant

TL;DR

This paper proposes a novel mechanism involving hydromagnetic waves generated within the helium rain layer to explain the prograde equatorial jet of Jupiter-like gaseous giants, linking interior magnetic phenomena to atmospheric jet formation.

Contribution

It introduces a new mechanism based on equatorial Magnetic-Archimedes-Coriolis waves that connects the interior magnetic fields to atmospheric jet dynamics, expanding beyond convection-based models.

Findings

Hydromagnetic waves can generate thermal perturbations affecting atmospheric jets.

The mechanism explains the super-rotation of Jupiter's equatorial jet.

It offers insights into the differing jet directions on Uranus and Neptune.

Abstract

Gaseous giants are characterized by their deep atmospheres, which lack clear boundaries with their interiors; therefore, their internal states could directly influence atmospheric dynamics. So far, most modeling studies have considered deep convection as the primary mechanism by which the interior influences atmospheric dynamics. In this work, we propose another possible mechanism that might crucially determine the appearance of gaseous giants' atmospheric cloud-top jet winds, tracing them to a typical hydromagnetic wave (the so-called equatorial Magnetic-Archimedes-Coriolis wave) generated within the stably stratified, strongly magnetized helium rain layer. The associated thermal perturbations can propagate upward through the convective molecular hydrogen envelope, eventually affecting the atmospheric thermal structure - the zonal inhomogeneities that are conducive to the formation of the eastward atmospheric equatorial jet (super-rotation). Our results have important implications for understanding the equatorial dynamics of gaseous giants. This mechanism could also help explain the equatorial westward jets (sub-rotation) observed on Uranus and Neptune, which lack the helium rain layers.