A thermosphere/ionosphere general circulation model with coupled electrodynamics

TLDR

The study introduces a new simulation model of upper atmospheric dynamics that self‑consistently couples electrodynamic interactions between the thermosphere and ionosphere. The NCAR/TIE‑GCM computes wind‑driven dynamo electric fields and currents, then applies them to neutral and plasma motions within a realistic geomagnetic field geometry. Simulations at solar‑maximum equinox conditions confirm that eastward electric fields lift the ionosphere, reduce ion drag, and enable strong eastward winds, while wind‑generated vertical fields produce co‑directional plasma drifts that further diminish ion drag and amplify zonal winds.

Abstract

A new simulation model of upper atmospheric dynamics is presented that includes self‐consistent electrodynamic interactions between the thermosphere and ionosphere. This model, which we call the National Center for Atmospheric Research thermosphere‐ionosphere‐electrodynamic general circulation model (NCAR/TIE‐GCM), calculates the dynamo effects of thermospheric winds, and uses the resultant electric fields and currents in calculating the neutral and plasma dynamics. A realistic geomagnetic field geometry is used. Sample simulations for solar maximum equinox conditions illustrate two previously predicted effects of the feedback. Near the magnetic equator, the afternoon uplift of the ionosphere by an eastward electric field reduces ion drag on the neutral wind, so that relatively strong eastward winds can occur in the evening. In addition, a vertical electric field is generated by the low‐latitude wind, which produces east‐west plasma drifts in the same direction as the wind, further reducing the ion drag and resulting in stronger zonal winds.