Impacts of Ionospheric Conductance on Magnetosphere‐Ionosphere Coupling

Abstract

AbstractUnderstanding the consequence of the complex interplay between solar flare and geomagnetic storm on the magnetosphere‐ionosphere (M‐I) coupling is a critical aspect to space weather research. This is the first attempt to simulate the concurrent solar flare and geomagnetic storm effects on M‐I coupling using the state‐of‐art geospace model which integrates Lyon‐Fedder‐Mobarry ‐Thermosphere‐Ionosphere‐Electrodynamics General Circulation Model —the Rice Convection ring current Model (LTR) in a self‐consistent way. Our results indicate that dayside E‐region electron density enhancements peak nearly at the same time as the flare and these electron density enhancements at middle latitudes are not very sensitive to storm forcing. F‐region electron densities also have an immediate response to solar flares but take longer to recover compared to E‐region ionosphere, and dayside F‐region electron density enhancements are more prominent for more stormy conditions. These dayside middle‐latitude F‐region enhancements intensify tongue of ionization in the polar cap region. Both E‐ and F‐region electron density increases contribute to polar ionosphere conductance enhancements that have both local and global consequences. Flare‐induced conductance enhancements tend to reduce the amount of Joule dissipation into upper atmosphere and cross polar cap potential around solar flare peak (12:00 UT), and increase dayside field aligned currents and Joule dissipation afterward (12:20–13:30 UT). These effects are more appreciable for stronger solar wind driving conditions. These simulation results provide important references for interpreting observed solar activity/cycle dependence of magnetosphere‐ionosphere coupling phenomena.