Two-dimensional structure of the co-planar and non-coplanar magnetopause during reconnection

Abstract

The two-dimensional (2-D) magnetopause transition during reconnection is investigated with large-: ale hybrid simulations. Contrary to previous studii;, but in agreement with observations, the two discoir inuities that form are not an intermediate shock or a slow shock. A 2-D reconnection configuration develops with jumps that do not satisfy Rankine-Hugoniot conditions of known discontinuities. All plasma quantities are fairly constant between the discontinuities. This region is characterized by a nearly unchanged sheath density, slight temperature enhancement, and significant magnetic field depression and thus resembles the "Sheath Transition Layer" of Song et al. [1989]. For a non-coplanar magnetic field Bzo, the plasma βattains very high values on the outflow side where Bzo and the Hall-generated field cancel, and the jet becomes unstable. In this case, ;e magnetosheath-side discontinuity resembles the oftt-; observed rotational discontinuity. Copyright 1999 by the American Geophysical Union.