Geoscience Reference
In-Depth Information
Fig. 4.3
Electric potentials obtained from Cluster EDI measurements that were mapped into the
Southern Hemisphere. The potentials are shown as a function of magnetic latitude (outer circle at
60
ı
) and magnetic local time for 8 clock-angle orientations (45
ı
-wide sectors) of the IMF. The
background color shows the potential value, according to the color bar in the center; the lines are
drawn at fixed potential values with a 3-kV spacing. The minimum and maximum potentials are
listed at the
bottom
, and the total cross-polar potential drop is given at the
upper right
of each dial
from
Annales Geophysicae
by Copernicus GmbH Copyright 2012 (Reproduced with permission
of European Geosciences Union)
for northward IMF and increase steadily with southward-turning IMF
B
z
.Inthe
Northern Hemisphere, the maximum amplitude is achieved for sector 5
B
z
=B
y
,
whereas at the Southern Hemisphere this is the case for sector 3
B
z
=B
y
C
.
Moreover, for all three sectors with IMF B
y
C
(sectors 1-3), the average neutral wind
amplitudes of the Southern Hemisphere are significantly (10-20%) larger than of the
Northern Hemisphere, whereas the opposite is true for IMF B
y
in sectors 5-7. The
total average of the wind amplitudes is about the same in the Northern Hemisphere
