Heidelberg 2006 – wissenschaftliches Programm
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EP: Extraterrestrische Physik
EP 2: Erdmagnetosph
äre
EP 2.4: Fachvortrag
Montag, 13. März 2006, 17:00–17:15, B
Wave-Particle Coupling Upstream of Earth’s Quasi-Parallel Bow Shock — •Arpad Kis1, Klecker Berndt1, Manfred Scholer1, Elisabeth Lucek2, Henri Rème3, Iannis Dandouras3, and Harald Kucharek4 — 1MPE, Garching, Germany — 2Imperial College, UK — 3CESR, Toulouse, France — 4Univ. of New Hampshire, Durham
In the region upstream of Earth’s quasi-parallel bow shock diffuse energetic particles are scattered in pitch-angle by low-frequency, large-amplitude MHD waves. On the other hand, these waves are excited locally by the energetic ions. The quasi-linar theory describing this intimate coupling between waves and particles has been verified in the past through observations, and the results show that the model predicts the transverse wave energy density in a satisfactory way. However, until now there has been no study of the relation between the observed and predicted wave energy density as a function of distance from the shock. We performed a detailed analysis of the upstream energetic particle event observed by Cluster on 18 February 2003. The results indicate that at distances less than 3 Re from the shock the observed transverse wave power energy density is substantially lower than the predicted one. We found that the compressional wave power energy density increases exponentially with decreasing distance from the shock. It is concluded that compressional waves in the close vicinity of the quasi-parallel shock play an important role by trapping the energetic diffuse ions.