Walen & slow-mode shock analyses applied to high-speed flows of the near-Earth magnetotail
Seminar Room 1, Newton Institute
Observed changes in the high-speed magnetotail flow direction from earthward to tailward and vice versa have been interpreted as a reconnection X-line passing by the spacecraft. Here we analyze several such events using Cluster observations from the near-Earth magnetotail. We investigate to what extent tailward and earthward flows satisfy the Walen condition and discuss whether tailward flows are more likely to do so due to the obstacle posed by the inner magnetosphere to earthward flows. The hypothesis that tailward flows would satify the Walen relation more readily than earthward flows across Petschek-type slow-mode shocks will be examined based on the Rankine-Hugoniot shock jump conditions. These results suggest that X-lines may form closer to the Earth than X = -20 Re.