Magnetosphere-Ionosphere Coupling Through E-region Turbulence: Anomalous Conductivities and Frictional Heating

TL;DR

This paper investigates how E-region turbulence causes anomalous conductivities and frictional heating, significantly affecting ionospheric conductance and improving the accuracy of space weather models during geomagnetic storms.

Contribution

It derives correction factors for turbulent conductivities and calculates heating rates, highlighting the importance of including these effects in global magnetospheric simulations.

Findings

Anomalous conductivities can double Pedersen conductance during storms.

Turbulence-driven effects help explain overestimations in MHD models.

Inclusion of these effects improves space weather predictive models.

Abstract

Global magnetospheric MHD codes using ionospheric conductances based on laminar models systematically overestimate the cross-polar cap potential during storm time by up to a factor of two. At these times, strong DC electric fields penetrate to the E region and drive plasma instabilities that create turbulence. This plasma density turbulence induces non-linear currents, while associated electrostatic field fluctuations result in strong anomalous electron heating. These two effects will increase the global ionospheric conductance. Based on the theory of non-linear currents developed in the companion paper, this paper derives the correction factors describing turbulent conductivities and calculates turbulent frictional heating rates. Estimates show that during strong geomagnetic storms the inclusion of anomalous conductivity can double the total Pedersen conductance. This may help explain the overestimation of the cross-polar cap potentials by existing MHD codes. The turbulent conductivities and frictional heating presented in this paper should be included in global magnetospheric codes developed for predictive modeling of space weather.