Quasi-2-day and tidal wave modulation of the lower E-region winds and equatorial electrojet during sudden stratospheric warming events

Abstract:

We present an analysis of the perturbations and wave characteristics in equatorial electrojet (EEJ) and lower E-region neutral winds during four sudden stratospheric warming (SSW) events. The wind field data are derived from two Meteor Radars located at Kototabang (0.20°S, 100.32°E) and Biak (1.18°S, 136.10°E) and a Medium Frequency radar located at Pameungpeuk (7.65°S, 107.69°E). The changes in EEJ are analyzed based on the magnetometer data located at Tirunelveli (8.67°N, 77.81°E) and Alibag (18.64°N, 72.87°E) stations. During four events, EEJ usually displays a typical semidiurnal variation pattern and the prominent quasi-2-day periodic oscillations appear in the meridional and zonal wind fields, which are likely associated with SSWs. Based on the time-period wavelet analysis, the enhanced quasi-2-day wave (QTDW) components are observed in the amplitudes of enhanced semidiurnal tides in EEJ but not in the enhanced diurnal tidal amplitudes. The occurrence of the enhanced QTDWs coincides with the occurrence of the enhanced semidiurnal tides as well as the semidiurnal perturbations in EEJ. Most importantly, the QTDWs enhancements in the meridional and zonal wind fields are also observed and present a good agreement with those in the semidiurnal tidal amplitudes in EEJ. Our results indicate that the enhanced QTDWs during the SSWs will modulate the semidiurnal tides and give rise to the EEJ disturbance through E region electrodynamics process.