Validation of Ionospheric Models at Mid‐ and High‐Latitudes: Climatological Performance of WACCM‐X (SD) and TIE‐GCM in foF2

Plain Language Summary: Lack of observations, as well as complex chemistry and dynamics, make the high‐latitude ionosphere challenging to model in comparison to low‐ and mid‐latitudes. We here investigate the performance of the Thermosphere‐Ionosphere‐Electrodynamics General Circulation Model (TIE‐GCM), the Whole Atmosphere Community Climate Model with thermosphere and ionosphere extensions (WACCM‐X), and the Empirical Canadian High Arctic Ionospheric Model (E‐CHAIM), using 72 years of ionosonde observations at Chilton, UK, and Resolute Bay, Canada. We find the physics‐based models strongly overestimate critical frequency, especially during the winter at high‐latitudes. We also observe an asymmetry in the magnitude of critical frequency values between the March and September equinoxes, which is misrepresented by models at both mid‐ and high‐latitudes. Additionally, we find that including lower atmospheric forcing with the WACCM‐X Specified Dynamics (SD) model can improve representation of day‐to‐day variability within physics‐based models, but amplifies overestimations of critical frequency during the winter.