Ionospheric Conductance Spatial Distribution During Geomagnetic Field Reversals

Abstract

The conductivity of the ionosphere is extremely important in geophysical processes and plays acritical role in magnetosphere-ionosphere-thermosphere coupling. Understanding its nature is essential tounderstand the physics of ionospheric electrodynamics. Earth?s magnetic field, which varies greatly ingeological time scales, is among the main variables involved in ionospheric conductivity. The present field canbe approximated by a magnetic dipole that accounts for ~80% of the magnetic field at the Earth?s surface, plusmultipolar components making up the remaining ~20%. During a polarity transition the field magnitudediminishes to about 10% of its normal value at the expense, most likely, of decreasing the dipolar componentand becoming mostly multipolar in nature. The effects of geomagnetic field variations on the spatial structureof Hall and Pedersen conductances are analyzed in the present work considering some possible reversalscenarios. The spatial structure of both conductances changes significantly with sharp spatial gradients. Theconductivity peak heights also change, moving to upper heights as expected for weaker field configurations.