Earth Planets Space, Vol. 50 (No. 3), pp. 295-302, 1998
Eduard Dubinin1,2,4, Konrad Sauer1,4, Magda Delva3,4, and Aleksandr Skalsky2,4
1Max-Planck-Institut für Aeronomie, D-37191 Katlenburg-Lindau, Germany
2Space Research Institute, Russian Academy of Sciences,117810 Moscow, Russia
3Space Research Institute, Austrian Academy of Sciences, Inffeldgasse, 12, 8010, Graz, Austria
4International Space Science Institute (ISSI), Hallerstrasse 6, 3012 Bern, Switzerland
(Received August 4, 1997; Revised January 19, 1998; Accepted February 9, 1998)
Abstract: A noticeable bending of the magnetic field lines in the Martian upstream region is observed. Variations of the field are controlled by the IMF and the foreshock geometry. The sign of B changes at the crossing of the tangent surface, which borders foreshock and the undisturbed solar wind. Perturbations of the magnetic field are centered at the plane which is normal to the tangent surface and intersects the bow shock at the tangent point. All observed signatures suggest that the current, providing field variations, is localized near the tangent surface. Although, two models are discussed, neither of them is able to explain all observed features satisfactorily.