Thermosphere-ionosphere effects due to forcing from “above” and “below” as captured by TIEGCM-ICON

The lower to upper atmosphere vertical coupling via atmospheric solar tides is very variable and affects the dynamics, composition and electrodynamics of thermosphere-ionosphere (TI) system. In addition, complex solar wind forcing is always impacting the high latitude region and its effects can extend to the mid- and low latitude region.  The Ionospheric Connection (ICON) explorer mission provides almost 3 years of data and an opportunity to examine the variation in the TI due to lower atmospheric and MI forcing. This is facilitated by the ICON Level4 product, the thermosphere-ionosphere-electrodynamics general circulation model (TIEGCM) driven by tides fitted to ICON observations via the Hough Mode Extension (HME) method. The effects of the upward propagating tides can be isolated by examining the difference between two TIEGCM simulations with and without tidal HME forcing at the model’s lower boundary, while the effects of solar and magnetospheric variability can be estimated by the difference to a simulation with constant solar and geomagnetic forcing.

In this presentation we use over 2 years of TIEGCM simulations to evaluate the model by comparing primarily to ICON observations and examine the captured TI variations. A special focus in our comparison will be on the neutral wind and its two-way coupling to ion drift and plasma distribution. For specific time period we will delineate the contributions due to lower atmospheric tidal forcing from the one due to solar and magnetospheric forcing and quantify the separate effects on the neutral wind, ion drift, and plasma variation.