Walen
and
Slow-mode Shock Analyses Applied to High-speed Flows in the Near-Earth
Magnetotail
S.
Eriksson, C. Mouikis, M. W.
Dunlop, M. Oieroset, D. N. Baker, C. Cully, H. Reme, A. Balogh, and R.
E. Ergun
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 three
such events using Cluster observations from the near-Eart magnetotail.
Initial results suggest that taiward flows are accelerated across
Petschek-type slow-mode shocks based on the Rankine-Hugoniot shock jump
conditions and the Walen relation. Eartward flows, however, tend to
fail these tests. A possible expanation may be the obstacle posed by
the higher magnetic field pressure of the inner magnetosphere. These
events suggest that X-lines formed in the near-Earth region within
X=-20 Re.