A Turbulent Heating Model Combining Diffusion and Advection Effects for Giant Planet Magnetospheres

TL;DR

This paper develops a combined turbulent heating model for giant planet magnetospheres, integrating diffusion and advection effects to better match observed ion temperature profiles from Jupiter and Saturn.

Contribution

It introduces a unified model that incorporates both diffusion and advection, ensuring physical consistency and improving temperature predictions at different radial distances.

Findings

Combined model aligns with observations at larger radii.

Diffusion enhances temperature agreement at smaller radii.

Previous advection-only models remain valid at larger distances.

Abstract

The ion temperature of the magnetospheres of Jupiter and Saturn was observed to increase substantially from about 10 to 30 planet radii. Different heating mechanisms have been proposed to explain such observations, including a heating model for Jupiter based on MHD turbulence with flux-tube diffusion. More recently, an MHD turbulent heating model based on advection was shown to also explain the temperature increase at Jupiter and Saturn. We further develop this turbulent heating model by combining effects from both diffusion and advection. The combined model resolves the physical consistency requirement that diffusion should dominate over advection when the radial flow velocity is small and vice versa when it is large. Comparisons with observations show that previous agreements, using the advection only model, are still valid for larger radial distance. Moreover, the additional heating by diffusion results in a better agreement with the temperature observations for smaller radial distance.