The Polar Stratosphere of Jupiter

TL;DR

This paper reviews recent research on Jupiter's polar stratosphere, highlighting how auroral particle precipitations influence chemical distributions, thermal structure, and the complex interplay of chemistry and dynamics in the upper atmosphere.

Contribution

It synthesizes current understanding of auroral impacts on Jupiter's polar atmosphere, emphasizing ion-neutral reactions, jet dynamics, and the resulting chemical and haze distributions.

Findings

Auroral particle precipitations alter hydrocarbon abundances.

Ion-neutral reactions produce species with specific spatial distributions.

Dynamical decoupling leads to polar and subpolar haze systems.

Abstract

Observations of the Jovian upper atmosphere at high latitudes in the UV, IR and mm/sub-mm all indicate that the chemical distributions and thermal structure are broadly influenced by auroral particle precipitations. Mid-IR and UV observations have shown that several light hydrocarbons (up to 6 carbon atoms) have altered abundances near Jupiter's main auroral ovals. Ion-neutral reactions influence the hydrocarbon chemistry, with light hydrocarbons produced in the upper stratosphere, and heavier hydrocarbons as well as aerosols produced in the lower stratosphere. One consequence of the magnetosphere-ionosphere coupling is the existence of ionospheric jets that propagate into the neutral middle stratosphere, likely acting as a dynamical barrier to the aurora-produced species. As the ionospheric jets and the background atmosphere do not co-rotate at the same rate, this creates a complex system where chemistry and dynamics are intertwined. The ion-neutral reactions produce species with a spatial distribution following the SIII longitude system in the upper stratosphere. As these species sediment down to the lower stratosphere, and because of the progressive dynamical decoupling between the ionospheric flows and the background atmosphere, the spatial distribution of the auroral-related species progressively follows a zonal distribution with increasing pressures that ultimately produces a system of polar and subpolar hazes that extends down to the bottom of the stratosphere. This paper reviews the most recent work addressing different aspects of this environment.