Auroral Energy Flux and Joule Heating Derived From Global Maps of Field‐Aligned Currents

Abstract

We calculate auroral energy flux and Joule heating in the high‐latitude ionosphere for 27 geomagnetically active days using two‐dimensional maps of field‐aligned currents determined by the Active Magnetosphere and Planetary Response Experiment. The energy input to the ionosphere due to Joule heating increases more rapidly with geomagnetic activity than that due to precipitating particles. The energy flux varies more smoothly with time than Joule heating, which is impulsive in nature on time scales from minutes to tens of minutes. These impulsive events correlate well with recoveries in the Sym‐H index, with the maximum correlation when compared to Sym‐H recoveries 70 min later. Because of prior studies that have associated transient recoveries of Sym‐H with substorm expansions, the delay found here suggests that dissipation of energy in the ionosphere occurs during the substorm growth phase prior to the release of magnetic energy caused by diversion of tail currents.

Geomagnetically Quiet Period Analysis of Relativistic Electrons, Auroral Precipitation, Joule Heating, and Ring Current During the Years of 1999, 2000 and 2004

“…It is possible the Joule heating seen is associated with the partial ring currents present even during geomagnetically quiet days at all Dst index levels, as shown by Le et al [37]. The relativistic electron fluxes seen could result from viscous interactions that transfer energy from the solar wind to the magnetic field lines, which can energize the electrons in the radiation belts [36].…”

“…When the solar wind enters the Earth's magnetosphere, the density of relativistic electrons increases in the initial phase, these electrons are then lost by different processes such as charge exchange of magnetospheric ions and pitch angle loss at mirror points in the radiation belts [36]. The precipitation of ions and electrons from the magnetosphere onto the ionosphere causes the aurora through collisions of these ions and electrons with neutral atoms in the atmosphere.…”

“…Joule heating, therefore, acts as an energy sink for the energy deposited by the solar wind [24]. Previous studies [36] have studied auroral precipitation and Joule heating during geo-magnetically active periods, but this work studied them during the quiet periods. These energy deposition mechanisms can dramatically affect the state of the terrestrial atmosphere through the increase in neutral gas density, temperature, and ionization.…”

“…Therefore, it is essential to take them into account in ionospheric modeling during magnetic storms and quiet periods. Ionospheric modeling is known to be important for real-world applications such as satellite trajectories and radio wave propagation [36].…”

COMPASS: A New COnductance Model Based on PFISR And SWARM Satellite Observations

“…(2018), Robinson et al. (2020, 2021), and Robinson and Zanetti (2021). Our model provides another option for the community to estimate the global conductance distribution using the FAC information from measurements, empirical models of FACs, or numerical models that can calculate FACs.…”