The Sun–Earth Connection 219
FIGURE 8 (a) Illustration of the
blunt body shape of the
magnetosphere, showing some
gossamer “shells” of magnetic field
surfaces along which charged
particles drift, and the
magnetopause. (Rice University)
(b) Magnetospheric boundaries
described in the text. The
magnetopause nominally separates
solar wind and magnetospheric
domains. (The source of this
material is the Cooperative
Program for Operational
Meteorology, Education, and
Training (COMET©r) Web site at
http://meted.ucar.edu/ of the
University Corporation for
Atmospheric Research (UCAR)
pursuant to a Cooperative
Agreement with National Oceanic
and Atmospheric Administration.
Copyright 1997–2004 University
Corporation for Atmospheric
Research. All Rights Reserved.)dipole field. The northward interplanetary field, which is
parallel to the Earth’s dipole field at the equator, produces
a magnetically closed magnetosphere. The southward field,
which is antiparallel to the Earth’s dipole field at the equa-
tor, produces a magnetically open configuration with the
polar region fields of the Earth connected to the interplan-
etary field. These differences greatly affect the transfer of
both energy and particles from the solar wind into geospace.
For the northward case, the solar wind interaction resem-
bles a viscous boundary interaction at the magnetopause,
and there is minimal exchange of energy and particles. For
the southward case, the charged particles in interplanetary
space have access to the polar regions along interplane-
tary field lines. An electric field associated with solar wind
convection (E=−V×B, whereVis the solar wind ve-
locity andBits magnetic field), maps along open field lines
into polar regions where it drives vigorous magnetosphere
and ionosphere circulation as in Fig. 10. The two-celled
vortical convection pattern has been observed in the iono-
sphere by high-latitude radars and can be inferred from