Comparative Analysis of Ionospheric Responses to Ultra‐Fast Kelvin Waves With Wavenumbers 1, 2, and 3

Abstract We employed zonal wind data from Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics Doppler Interferometer, equatorial electrojet (EEJ) measurements from Jicamarca (12°S, 77°W), and global ionospheric total electron content (TEC) maps to investigate the effects of ultra‐fast Kelvin waves (UFKW) with zonal wavenumbers 2 and 3 propagating eastward (E2, E3) in the equatorial mesosphere on both ionospheric TEC and EEJ signatures, as well as their differences in ionospheric response characteristics compared to E1 waves. Periodic components in zonal wind, EEJ, and TEC are quantified through the least squares spectral fitting. Our findings reveal three distinct categories of UFKW events: Type 1 exhibits both TEC and EEJ responses, Type 2 shows TEC response without EEJ signature, and Type 3 displays neither TEC nor EEJ response. The finding reveals distinct seasonal dependencies in TEC responses: E2 and E3 waves exhibit significant seasonality, whereas E1 waves show negligible seasonal variation. Furthermore, E1 waves demonstrate higher ionospheric response occurrence rates compared to E2 and E3 waves. For E1 waves, shorter periods, larger amplitudes, and longer vertical wavelengths correlate strongly with enhanced ionospheric responsiveness. Conversely, amplitude exerts minimal influence on ionospheric responses for E2 and E3 waves. For E2 and E3 waves temporally coincident with E1 waves, E2 and E3 waves may elevate Type 2 event occurrence among concurrent E1 waves, while E1 waves tend to suppress ionospheric response capability in coincident E2 and E3 waves, increasing Type 3 event prevalence.