HR: 08:05h
AN: SA11B-01 INVITED    [Abstracts]
TI: Detailed features of the low latitude ionosphere-thermosphere system, as derived from CHAMP observations
AU: * Luhr, H
EM: hluehr@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Telegrafenberg, Potsdam, 14473, Germany
AU: Stolle, C
EM: stolle@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Telegrafenberg, Potsdam, 14473, Germany
AU: Haeusler, K
EM: kathrin@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Telegrafenberg, Potsdam, 14473, Germany
AB: The CHAMP satellite, launched in July 2000, provides an extensive and valuable base of ionospheric and thermospheric measurements at low altitudes (~400 km) for more than 7 years. CHAMP carries a varity of advanced instrumentation such as a three-axes accelerometer sensing the ambient air density and thermospheric winds. The very sensitive magnetometer on board is able to detect faintest currents. Furthermore radio occultation and GPS topside sounding help to image the structure of the ionospheric electron density. These observations are accompanied by the local electron density and temperature measurements of the Langmuir probe. The CHAMP data base disclosed several climatological aspects of the upper atmosphere. One prominent feature of the thermosphere at low magnetic latitudes is the mass density anomaly showing in many respects resemblance with the equatorial ionisation anomaly. The ionisation anomaly itself has recently been shown to exhibit a pronounced 4-peaked longitudinal structure in the post-sunset local time sector (e.g. Immel et al., 2006). We could show that this longitudinal structure is also present during day time hours. Furthermore, it could be deduced from CHAMP data that the thermospheric zonal wind also yields a wave-4 pattern, but the phase of this wind component switches sign between day time and evening hours. Reasons for these observations are still under investigation. Another rather novel result is the identification of faint magnetic signatures caused by equatorial spread-F (plasma bubbles). Based on a systematic investigation the global distribution of the bubble's magnetic signature has been derived and a detailed climatological picture of their occurrence rate could be drawn.
DE: 2415 Equatorial ionosphere
DE: 2439 Ionospheric irregularities
DE: 3369 Thermospheric dynamics (0358)
DE: 3389 Tides and planetary waves
SC: SPA-Aeronomy [SA]
MN: 2007 Fall Meeting