Climate and Weather of the Sun-Earth System

CAWSES

Aim: Investigation of density enhancements in the thermospheric cusp region.

In recent models it is generally assumed that the thermospheric structure is mainly controlled by the extreme-ultra violet (EUV) solar radiation, while the magnetic activity should play a minor role. Our recent measurements indicate, however, that this is not the case. In this project we investigate the importance of the ionosphere-thermosphere coupling for the dynamics of the upper atmosphere at high latitudes. We are focusing on the auroral region, where most of the Joule heating occurs. The study will be based on observations from CHAMP and the EISCAT radar facilities. Our final aim is to characterize the ionospheric heating mechanisms which cause thermospheric density enhancements and drive winds. The roles of solar wind input and EUV solar flux shall also be identified. (Stefanie Rentz)

Aim: Investigation of nonmigrating thermospheric tidal waves in density and wind as observed by CHAMP.

The dynamics of the upper atmosphere is primarily determined by the energy input of the sun in this height range and partly controlled by the Earth's magnetic field. Yet recently, growing evidence is presented that also tidal effects originating in the tropical troposphere are able to modulate upper atmospheric parameters. Within this project it is intended to identify these tidal signatures in the zonal wind and density and to correlate them with atmospheric features at the bottom side thermosphere. For the research we make use of accelerometer measurements on CHAMP from which the zonal wind and the air density can be derived. (Kathrin Häusler) 

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CAWSES