Day‐To‐Day Variability of the MLT DE3 Using Joint Analysis on Observations From TIDI‐TIMED and a Meteor Radar Meridian Chain

Abstract

AbstractIn the present work, daily variation of eastward propagating diurnal tide with zonal‐wave number 3 (DE3) is derived from joint analysis on observations from Thermosphere Ionosphere Mesosphere Energetics and Dynamics Doppler Interferometer and a meteor radar chain around meridian 120°E during years of 2012–2015 and 2018–2020 via a novel method. Together with empirical tidal modes (ETMs), which are based on the Global Scale Wave Model, daily DE3 in horizontal winds are extracted. ETMs characterize the two‐dimensionally latitude‐altitudinal tidal structure with consideration of tidal dissipation, and thus makes it possible to obtain the DE3 tide extending to pole‐to‐pole in latitudes and covering 80–140 km on altitudes. Quantitatively analyzing day‐to‐day variability of mesosphere and lower thermosphere DE3 reveals that the variation of tidal phase is the main contributor to the DE3 day‐to‐day variability for both zonal and meridional winds. The strength of tidal‐phase induced variability has a clear seasonal dependence that is strong around June and December solstices. Prominent semiannual oscillation (SAO) for zonal (∼16%) and meridional (∼24%) winds are revealed, and annual oscillation (AO) is superposed on the SAO for the DE3 in meridional winds (∼9%). Tidal‐phase induced variability is generally stronger in solar minima (2018–2020) than that in solar maxima (2013–2015). Furthermore, a comparison with simulations using the Whole Atmosphere Community Climate Model eXtended is discussed. The simulations confirm that the primary role of tidal‐phase variations on the day‐to‐day variability. The model does not reproduce the SAO as shown in observations, while the AO in meridional winds is simulated well.