Deep rotating convection generates the polar hexagon on Saturn

TL;DR

This paper presents a 3D nonlinear simulation showing how deep thermal convection can spontaneously produce Saturn's polar hexagon through self-organized turbulence and vortex pinching.

Contribution

It introduces a self-consistent, fully nonlinear model demonstrating the formation of Saturn's hexagonal polar jet via turbulence-driven vortex dynamics.

Findings

Simulation reproduces polar cyclones and polygonal jets.

Vortex pinching leads to polygonal jet formation.

Mechanism likely explains Saturn's observed hexagon.

Abstract

Numerous land and space-based observations have established that Saturn has a persistent hexagonal flow pattern near its north pole. While observations abound, the physics behind its formation is still uncertain. Although several phenomenological models have been able to reproduce this feature, a self-consistent model for how such a large-scale polygonal jet forms in the highly turbulent atmosphere of Saturn is lacking. Here we present a 3D fully-nonlinear anelastic simulation of deep thermal convection in the outer layers of gas giant planets which spontaneously generates giant polar cyclones, fierce alternating zonal flows, and a high latitude eastward jet with a polygonal pattern. The analysis of the simulation suggests that self-organized turbulence in the form of giant vortices pinches the eastward jet, forming polygonal shapes. We argue that a similar mechanism is responsible for exciting Saturn's hexagonal flow pattern.