Geoscience Reference
In-Depth Information
April 14, 1978
500
0
AU
2
500
AL
5
B z (SM)
0
25
20
0
Chatanika E N
2
20
20
0
Chatanika E E
2
20
15
0
Millstone E N
215
5
0
Millstone E E
2
5
0.5
0
Jicamarca E E
2
0.5
00
04
08
12
UT
16
20
24
Figure 3.23 Auroral (AU, AL) and interplanetary ( B z ) magnetic field data along with
auroral (Chatanika andMillstone) and equatorial (Jicamarca) electric fieldmeasurements.
The shaded region corresponds to a rapid decrease in magnetospheric convection appar-
ently triggered by a northward turning of the interplanetary field. [After Kelley et al.
(1979). Reproduced with permission of the American Geophysical Union.]
interaction abruptly decreases (see Chapter 8). The increasing activity currents
(Region 1 > Region 2) yield an eastward perturbation on the dayside and a west-
ward perturbation at night. Decreasing activity current unbalance (Region 2 >
Region 1) yields the opposite changes.
An event similar to Nishida's original study shown in Fig. 3.21 was studied
on February 17, 1976, using electric field data as well as magnetic measure-
ments. The IMF, the auroral zone electric field, and the equatorial electric field all
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