Helmholtz Centre Potsdam
GFZ German Research Centre for Geosciences
Abstract (EDOC: 15886)
Recent years provided more and more evidence for tidal signatures in various kinds of upper atmospheric measurements. In this talk special emphasis is put on non-migrating tides. Several of these tidal modes are believed to be generated in the lower atmosphere, and to propagate from here all the way up to the exosphere. Quantities, that reflect the characteristics of the tides very well, are thermospheric temperature and wind. Based on TIMED and CHAMP measurements the complete tidal spectrum has been derived for these two quantities at both MLT and upper thermospheric (400 km) altitudes. Main features of the tides will be presented, as deduced from these observations. The dynamics of the neutrals is partly transferred to charged particles in the ionospheric E-layer. For that reason some tidal signals are also observable in ionospheric parameters. Since the coupling conditions between neutral and charged particle vary over the course of a day (a year, a solar cycle), the recovery of the tidal signal in electrodynamic quantities is, due to its non-linear distortion, much more sophisticated. Even though, tidal signatures are quite evident in the observations during certain local times. We will show the amplitude and temporal variations for some of the prominent tidal components in the equatorial electrojet, in the vertical plasma drift and in electron density.
(2009): Tidal signatures in thermospheric and ionospheric quantities. AGU 2009 Fall Meeting.