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EP: Extraterrestrische Physik

EP 1: Magnetosph
äre und Ionosph
äre

EP 1.9: Vortrag

Freitag, 4. März 2005, 12:00–12:15, TU BH349

Strong Disturbance of the Upper Thermospheric Density due to Magnetic Storms: CHAMP Observation — •Huixin Liu and Hermann Lühr — GFZ Potsdam, Telegrafenberg, 14463 Potsdam

Strong enhancement of the upper thermospheric total mass density was observed by the CHAMP satellite at about 400 km altitude during three geomagnetic super storms occurring on October 29-30, 2003, October 30-31, 2003, and November 20-22, 2003. The corresponding density enhancement reached about 400 percent, 500 percent, and 800 percent of the quiet-time values in both noon and midnight sectors. The disturbance showed strong day-night and seasonal asymmetry. On the dayside, the average density enhancement was stronger in summer than in winter. This applies to the density enhancement expressed both in absolute (storm-quiet) and in percentage (storm-quiet/quiet) terms. On the nightside, however, no general rule can be drawn about the seasonal effect. Stronger density enhancement occurred in the summer hemisphere during the second and third storm events, but in the winter hemisphere during the first storm event. The relative intensity of the disturbance between day and night depends on the term we choose to describe it. When expressed in absolute terms, the density enhancement on the nightside was generally less than half of that on the dayside during all three storms. But the enhancement expressed in percentage terms on the nightside was comparable to or even larger than that on the dayside. The propagation of the disturbance from high to low latitudes was slower on the nightside in comparison to the dayside, The MSIS90 model was unable to reproduce most of the observed features during these storms.