Journal cover Journal topic
Annales Geophysicae Sun, Earth, planets, and planetary systems An interactive open-access journal of the European Geosciences Union
Ann. Geophys., 23, 3753-3764, 2005
© Author(s) 2005. This work is distributed under
the Creative Commons Attribution 3.0 License.
23 Dec 2005
The magnetotail reconnection region in a global MHD simulation
T. V. Laitinen1,2, T. I. Pulkkinen2, M. Palmroth2, P. Janhunen2, and H. E. J. Koskinen1,2 1University of Helsinki, Department of Physical Sciences, P.O.Box 64, FIN-00014 Helsinki, Finland
2Finnish Meteorological Institute, Space Research, P.O.Box 503, FIN-00101 Helsinki, Finland
Abstract. This work investigates the nature and the role of magnetic reconnection in a global magnetohydrodynamic simulation of the magnetosphere. We use the Gumics-4 simulation to study reconnection that occurs in the near-Earth region of the current sheet in the magnetotail. We locate the current sheet surface and the magnetic x-line that appears when reconnection starts. We illustrate the difference between quiet and active states of the reconnection region: variations in such quantities as the current sheet thickness, plasma flow velocities, and Poynting vector divergence are strong. A characteristic feature is strong asymmetry caused by non-perpendicular inflows. We determine the reconnection efficiency by the net rate of Poynting flux into the reconnection region. The reconnection efficiency in the simulation is directly proportional to the energy flux into the magnetosphere through the magnetopause: about half of all energy flowing through the magnetosphere is converted from an electromagnetic into a mechanical form in the reconnection region. Thus, the tail reconnection that is central to the magnetospheric circulation is directly driven; the tail does not exhibit a cycle of storage and rapid release of magnetic energy. We find similar behaviour of the tail in both synthetic and real event runs.

Citation: Laitinen, T. V., Pulkkinen, T. I., Palmroth, M., Janhunen, P., and Koskinen, H. E. J.: The magnetotail reconnection region in a global MHD simulation, Ann. Geophys., 23, 3753-3764,, 2005.
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