Observations of thermosphere and ionosphere changes due to the dissipative 6.5-day wave in the lower thermosphere

摘要

In the current work, temperature and wind data from theThermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED)satellite during the years 2002–2007 were used to describe theseasonal variations of the westward propagating 6.5-day planetarywave in the mesosphere and lower thermosphere (MLT). Thermosphericcomposition data from the TIMED satellite and ionospheric totalelectron content (TEC) from the International Global NavigationSatellite System (GNSS) Service were then employed to carry out twocase studies on the effect of this dissipating wave on thethermosphere/ionosphere. In both cases, there were westwardanomalies of ~ 30–40 m s?1 in zonal wind in the MLTregion that were caused by momentum deposition of the 6.5-day wave,which had peak activity during equinoxes. The westward zonal windanomalies led to extra poleward meridional flows in bothhemispheres. Meanwhile, there were evident overall reductions ofthermospheric column density O / N₂ ratio and ionospheric TECwith magnitudes of up to 16–24 % during these two strong 6.5-daywave events. Based on the temporal correlation between O / N₂and TEC reductions, as well as the extra poleward meridionalcirculations associated with the 6.5-day waves, we conclude that thedissipative 6.5-day wave in the lower thermosphere can cause changesin the thermosphere/ionosphere via the mixing effect, similar to thequasi-two-day wave (QTDW) as predicted by Yue and Wang (2014).