Regensburg 2007 – wissenschaftliches Programm

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EP: Fachverband Extraterrestrische Physik

EP 7: Solar-Terrestrische Beziehungen

EP 7.3: Vortrag

Dienstag, 27. März 2007, 17:00–17:15, H46

Determining orientation, thickness, and velocity for a 2D, non-planar magnetopause — •Adrian Blǎgǎu^1,2, Berndt Klecker¹, Götz Paschmann¹, Manfred Scholer¹, Stein Haaland^1,3, Octav Marghitu^2,1, and Elizabeth Lucek⁴ — ¹Max-Planck-Institut für extraterrestrische Physik, Garching, Germany — ²Institute for Space Sciences, Bucharest, Romania — ³University of Bergen, Norway — ⁴Imperial College, London, UK

Since the Cluster mission became operational we benefit from correlated measurements taken simultaneously at four points in space. The differences in the position and time of the satellites' encounter with the terrestrial magnetopause (MP) can be used in a timing method to infer its orientation, thickness and velocity. This multi-spacecraft technique, which assumes a planar MP, proves reliable and offers an independent check for various single-spacecraft techniques. We will present a case when the techniques of Minimum Variance Analysis on the magnetic field (MVAB), and Minimum Faraday Residue (MFR) provide different individual MP normals, included approximately in the same plane. Such a configuration is not necessarily related to experimental errors, but can have natural causes like a local bulge/indentation in the MP or a large amplitude traveling wave on this surface. The timing technique yields a normal well apart from the single-spacecraft normals, indicating that the underlying planar assumption is questionable. We explain our case by considering a 2D, non-planar magnetopause and discuss the influence of such a geometry on the results based on MVAB, MFR and DeHoffmann-Teller techniques.