Evaluation of Atmospheric 3-Day Waves as a Source of Day-to-Day Variation of the Ionospheric Longitudinal Structure

We report for the first time the day-to-day variation of the longitudinal structure in height of the F₂ layer (h_mF₂) in the equatorial ionosphere using multi-satellite observations of electron density profiles by the Constellation Observing System for Meteorology, Ionosphere and Climate-2 (COSMIC-2). These observations reveal a ∼3-day modulation of the h_mF₂ wavenumber-4 structure viewed in a fixed local time frame during January 30–February 14, 2021. Simultaneously, ∼3-day planetary wave activity is discerned from zonal wind observations at ∼100 km by the Ionospheric Connection Explorer (ICON) Michelson Interferometer for Global High-Resolution Thermospheric Imaging (MIGHTI). This signature is not observed at ∼180–250 km altitudes, suggesting the dissipation of this wave below the F-region. We propose that the 3-day variation identified in h_mF₂ is likely caused by the planetary wave-tide interaction through the E-region dynamo.