Magnetically Quiet‐Time Traveling Ionospheric Disturbances Over Mid‐Latitude Eastern Europe Observed by the Kharkiv Incoherent Scatter Radar During the 24th Solar Cycle

Abstract We have detected and characterize traveling ionospheric disturbances (TIDs) in the mid‐latitude ionosphere over Europe using data from the Kharkiv incoherent scatter (IS) radar. The study focused on observations near solstices and equinoxes during solar cycle 24 under magnetically quiet conditions. We examined the diurnal, seasonal, and solar activity dependencies of both large‐scale (LS) and medium‐scale (MS) TIDs, evaluating 140 TID events. Key estimated characteristics included energetic (relative amplitudes), temporal (dominant periods, frequency of occurrence), and spatial (heights of maximum relative amplitudes, vertical and horizontal phase velocities, and wavelengths) parameters. Our findings suggest that moving solar terminators are the primary generation mechanism for magnetically quiet‐time LS TIDs, though a contribution from auroral activity cannot be excluded. In contrast, MS TIDs under magnetically quiet conditions are likely initiated from a broader range of sources, including gravity wave dissipation, severe tropospheric convection, coupling processes between the E s ‐layer and F ‐region, polarization electric fields, and Perkins instability. We found a positive correlation between the heights of the maximum relative TID amplitudes and the solar activity for LSTIDs. The TID characteristics obtained during extremely quiet conditions provide a useful context for analyzing the possible TID response to localized energy releases including those of anthropogenic origin. Additionally, they enable improvements in global and regional ionospheric models by clarifying the contribution of wave processes to the overall energy budget of the atmosphere and ionosphere.