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Abstract The statistics of day‐to‐day tidal variability within 35‐day running mean windows is obtained from Michelson Interferometer for Global High‐Resolution Thermospheric Imaging (MIGHTI)/Ionospheric Connection Explorer (ICON) observations in the 90–107 km height region for the year 2020. Temperature standard deviations for 18 diurnal and semidiurnal tidal components, and for four quasi‐stationary planetary waves are presented, as function of latitude, altitude, and day‐of‐year. Our results show that the day‐to‐day variability (DTDV) can be as large as 70% of the monthly mean amplitudes, thus providing a significant source of variability for the ionospheric E‐region dynamo and hence for the F‐region plasma. We further validate our results with COSMIC‐2 ionospheric observations and present an approach to extend the MIGHTI/ICON results to all latitudes using Hough Mode Extension fitting, to produce global tidal fields and their statistical DTDV that are suitable as lower boundary conditions for nudging and ensemble modeling of TIE‐GCM. In the future, this will likely help to establish a data‐driven perspective of space weather variability caused by the tidal weather of the lower atmosphere. 

Abstract The semidiurnal tidal spectrum in the F‐region ionosphere obtained from hourly COSMIC‐2 Global Ionospheric Specification (GIS) data assimilation is greatly (>50%) enhanced during the January 2021 Sudden Stratospheric Warming (SSW). Moreover, the semidiurnal migrating tidal response in topside electron densities closely follows the day‐to‐day changes of the 10 hPa, 60°N zonal wind from MERRA‐2 during the SSW. The response is similar in the northern and southern crests of the Equatorial Ionization Anomaly (EIA) but persists toward higher magnetic latitudes and the EIA trough. A slight phase shift toward earlier local times is consistent with theoretical expectations of an E‐region dynamo driving and agrees with semidiurnal tidal diagnostics of MIGHTI/ICON zonal winds at 105 km. COSMIC‐2 GIS are the first data set to resolve the tidal weather of the ionosphere on a day‐to‐day basis and, therefore, provide a new perspective on space weather variability driven by lower and middle atmosphere dynamics.