Publication Date:
2016-06-10
Description:
We present a statistical study of dipolarization fronts (DFs), using magnetic field data from MMS and Cluster, at radial distances below 12R E and 20R E , respectively. Assuming that the DFs have a semi-circular cross-section and are propelled by the magnetic tension force, we used multi-spacecraft observations to determine the DF velocities. About three-quarters of the DFs propagate earthward and about one-quarter tailward. Generally MMS is in a more dipolar magnetic field region and observes larger-amplitude DFs than Cluster. The major findings obtained in this study are: (1)At MMS ∼57 % of the DFs move faster than 150km/s, while at Cluster only ∼35 % , indicating a variable flux-transport rate inside the flow-braking region. (2)Larger DF velocities correspond to higher B z -values directly ahead of the DFs. We interpret this as a snow plow-like phenomenon, resulting from a higher magnetic flux pile-up ahead of DFs with higher velocities.
Print ISSN:
0094-8276
Electronic ISSN:
1944-8007
Topics:
Geosciences
,
Physics
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