© Author(s) 2011. This work is distributed
under the Creative Commons Attribution 3.0 License.
A statistical and event study of magnetotail dipolarization fronts
1Space Research Institute, Austrian Academy of Sciences, 8042 Graz, Austria
2Institute for Theoretical Physics, Technical University Graz, 8010 Graz, Austria
Abstract. A study of dipolarization fronts of the Earth's magnetotail has been performed using seven years (2001–2007) of Cluster data. Events both with and without high-speed earthward flows are included. A superposed epoch analysis of the data shows that the dipolarization is preceeded by a decrease of Bz before the increase. The duration of the dipolarization tends to be decreasing with increasing velocity of the plasma flows. The thickness of the dipolarization front is on average 1.8 plasma inertial lengths, independent of the plasma velocity. We find that the events fall into two categories: Earthward and tailward moving dipolarizations. The dipolarization fronts can be assumed to be tangential discontinuities and the currents on the front have mainly a perpendicular component.