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A
1
1
D
F
N1
N2
2
2
B
(a)
IMF south
2
3
9
2
9
19
1
4
9
3
6
9
59
4
6
5
(b)
Figure 8.14
(a) Schematic diagram showing dayside merging (NI) and nightside recon-
nection (N2) in the noon-midnight meridian. (Courtesy of D. P. Stern.) (b) Time history
of convecting flux tubes that result from connection of a southward IMF to the earth's
magnetic field. The convection along path 1, 2, 3 is on open field lines, while the path
from 3, 4, 5, 6 to 1 is on closed field lines that connect to the southern hemisphere.
the magnetopause by waves and diffusion, creating an effective viscosity. Plasma
near the equatorial plane, which is just inside the magnetopause, the so-called
equatorial boundary layer, is set in motion antisunward. A return flow toward
the sun occurs on lower latitude field lines and is driven by back pressure in
the magnetosphere near midnight. The ionospheric convection signature of this
process is qualitatively identical to that created by direct connection with the
solar wind magnetic field or merging, except that even the antisunward con-
vective paths in the magnetosphere are on closed field lines. Figure 8.15a shows
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