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E
3
B CONVECTION
5 1000 m/s
67
Arc 2
Arc 1
66
T
1
375 s
Sunward
flow
65
1.83 kR boundary
@ 045315
(T
Super 2
1
375 s)
64
2.61 kR boundary
@ 045315
(T 1 375 s)
63
2
54
2
52
250
248A
2
46
244
Geographic east longitude
Figure 8.13 E
B
drift velocities along the footprint of Super 2 deduced from the double-
probe electric field data. The heavy and dashed lines denote the boundaries of 2.61 and
1
×
. An arrow marks
the location of the Super 2 footprint at that time. The rocket flew toward the southeast as
illustrated by the arrow parallel to the trajectory. [After Berg et al. (1994). Reproduced
with permission of the American Geophysical Union.]
.
83 kR luminosity at 5577, respectively, at 0453:15 UT
(
T
+
375 s
)
which magnetospheric plasma moves from a region located on closed magnetic
field lines to a region on open field lines. After merging takes place, the magne-
tospheric plasma moves antisunward along the path labeled 1, 2, and 3. Small
arrows show the corresponding convective path of the plasma in the ionosphere
as it moves from 1
to 2
to 3
. At point 3, open field lines from the Northern
and Southern Hemispheres reconnect in the equatorial plane and subsequently
convect sunward in the equatorial plasma sheet as closed field lines. Again, one
may alternatively view point 3 as a place where magnetospheric plasma makes
a transition from being an open field line to being a closed field line. From either
viewpoint, the subsequent convective paths of the plasma in the ionosphere and
magnetosphere, respectively, are 3
,4
,5
,6
,1
and 3, 4, 5, 6, 1. Note in this
figure that the ionospheric flow is shown on a relatively enlarged sphere so that
its features can be seen.
These basic elements of a two-cell convection pattern can also be attributed to
the viscous interaction process mentioned earlier (Axford and Hines, 1961). In
this process the momentum of the magnetosheath plasma is transmitted across
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