Solar Activity Driven 27‐Day Signatures in Ionospheric Electron and Molecular Oxygen Densities

The complex interactions in the upper atmosphere, which control height-dependent ionospheric response to 27-day solar rotation period, are investigated with superposed epoch analysis technique. signatures describing activity calculated from a proxy (F10.7) and wavelength-dependent extreme ultraviolet (EUV) fluxes (Thermosphere Ionosphere Mesosphere Energetics Dynamics/Solar EUV Experiment), corresponding conditions electron density profiles (Pruhonice ionosonde station) O2 (Global-scale Observations of Limb Disk). lag these extracted is applied characterize delayed at heights 100 300 km impact major absorption processes lower (dominated by O2) ionosphere O) discussed. observed variations delay regions good agreement model simulations preceding studies. Additionally, estimated significance correlation delays based on both parameters good. Thus, such as strong shift for low also reliably identified (up half cycle). confirms importance thermospheric coupling understand variability introduces method that could be additional stations future This would allow describe spatially, vertically temporally therefore may contribute further understanding improve modeling.