The Effects of IMF <i>B</i> _<i>y</i> on the Middle Thermosphere During a Geomagnetically “Quiet” Period at Solar Minimum

Numerical simulations using the National Center for Atmospheric Research (NCAR) thermosphere-ionosphere-electrodynamics general circulation model (TIE-GCM) are performed to elucidate effects of interplanetary magnetic field (IMF) on middle thermosphere composition during a “geomagnetically quiet” period from day year (DOY) 110–111 in 2019 (when Auroral electrojet (AE) index never exceeded 300 nT and Kp 2). In particular, this paper aims examine how Global-scale Observations Limb Disk (GOLD) mission observed daytime thermospheric O N2 column density ratio (∑O/N2) depletion at mid-latitudes originated under such condition. A comparison electric potential, Joule heating rate per unit mass, ion velocity, neutral temperature winds (∼160 km) between real IMF without east-west component (By) indicates that By dominant condition can enhance their strengths Consequently, ∑O/N2 with stronger magnitude (30% compared ∼8% By) larger disturbed area was introduced post-midnight sector high-latitudes due strong localized upwelling associated enhanced mass. The transported equatorward corotated local early morning, by GOLD latitudes daytime.