Terrestrial Impacts on the Ionosphere-Thermosphere via Global-Scale Waves: New Insights from Concurrent Satellite Observations

A selected group of global-scale waves from the lower atmosphere, including tides and Kelvin waves, significantly impacts the mean state and variability of the ionosphere-thermosphere (IT, 100-600 km) system. This coupling occurs mainly at low latitudes and is driven by global-scale waves originating in the tropical troposphere, such as the diurnal eastward propagating tide with zonal wave number s = -3 (DE3) and the quasi-3-day ultra-fast Kelvin wave with s = -1 (UFKW1). In this work, nearly 3 years of simultaneous in situ ion densities from Ion Velocity Meters (IVMs) onboard the Ionospheric Connection Explorer (ICON) near 590 km and the Scintillation Observations and Response of the Ionosphere to Electrodynamics (SORTIE) CubeSat near 420 km, along with remotely-sensed lower (ca. 105 km) and middle (ca. 220 km) thermospheric horizontal winds from ICON’s Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI) and a tidal model (CTMT) are employed to demonstrate a rich spectrum of global-scale waves coupling terrestrial variability with the IT system. This study highlights the need for simultaneous day and night satellite measurements in the ~100-200 km altitude region to better understand the impact of the lower atmosphere on the IT system, ultimately enabling improved space weather forecast capabilities.