Longitudinal Variations of the Thermospheric Zonal Wind Induced by Nonmigrating Tides as Observed by CHAMP
In July 2000 the very successful German mini-satellite mission CHAMP, an acronym for Challenging Minisatellite Payload, was launched. One of the scientific instruments on board is an accelerometer that allows us to derive the zonal wind at CHAMP’s altitude (~ 400 km). Previous to its launch, continuous and globally distributed measurements of the upper thermospheric wind have been rather sparse. With the launch of the CHAMP satellite we are now able to investigate the upper thermospheric zonal wind, and in particular its longitudinal variability, in a climatological sense. This capability has led to exciting and unanticipated findings such as the coupling from the troposphere to the thermosphere via nonmigrating tides. In this chapter we talk about the longitudinal variations of the CHAMP zonal wind at equatorial latitudes. Further, we present the nonmigrating tidal spectra embedded in the CHAMP zonal wind with special emphasis on the eastward propagating diurnal tide with zonal wavenumber 3 (DE3).
KeywordsZonal Wind Longitudinal Variation Diurnal Tide Magnetic Equator Semidiurnal Tide
We thank Jens Oberheide, Maura Hagan, and Astrid Maute for fruitful discussions on the topic. K.H. is supported by the Deutsche Forschungsgemeinschaft (DFG) through its Priority Program CAWSES (SPP1176).
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