High Latitude Magnetopause
Current Sheet
Hui Zhang, Q.- G. Zong, T. A. Fritz (BU)
S. Y. Fu (PKU)
M. G. G. T. Taylor (ESA)
S. Schaefer, K. H. Glassmeier (TUBraunschweig)
P. W. Daly (MPA)
H. Reme (CESR, France)
A. Balogh (Imperial College, UK)
1
Background
Antiparallel reconnection
(Crooker et al., 1979; Luhmann et al., 1984;
Moore et al., 2002)

By reconnection has been
confirmed by a MHD simulation
study [Crooker et al.,1998] and
observed by Cluster. [Zong et al., 2004,
2005]
Hall reconnection



Including j x B term in generalized Ohm’s law
Causes decoupling of ions from the magnetic field at the ion
skin depth to produce the ion diffusion region, quadrupolar
magnetic fields.
Signatures of Hall effect have been observed in the tail and
subpolar magnetopause. [Oieroset et al., 2001; Mozer et al., 2002;]
2
3
Mar 23, 2002 Cluster/C1
M’pause
∆By=40 nT
4
Energetic Particle Fluxes
Cluster/RAPID
5
Magnetic field
Clock Angle
0
Bz
By
-90
90
180
arctan (BY/BZ)
6
1133-1145UT,
Mar. 23, 2002
7
Hall Reconnection
x
x
x
8
PAA results
Minimum Variance Direction:
(-0.927, 0.135, -0.351)GSE
Bz
 30%
Bt
Consistent with Hall
reconnection theory.
[Shay et al., 1999]
9
Magnetic Field
4 S/C
10
Conclusions
By reconnection event observed by Cluster
shows bipolar signatures which is consistent
with Hall effect in the reconnection.
Ion pitch angle evolution may indicate ion
carries Hall current.
Energetic particles can be trapped in the high
latitude magnetopause current sheet.
11