Return to "The Structure of the Magnetosphere" by
C. T. Russell.
"Slow Mode Transition in the Frontside Magnetosheath:"
This is a brief summary of "Slow Mode Transition in the Frontside
Magnetosheath" by P. Song at
UCAR,
C. T. Russell at
IGPP, and M. F. Thomsen at
LANL. This paper was one of the references in C. T. Russell's "The
Structure of the Magnetopause," which I am attempting to
summarize.
A slow mode version of the fast mode shock in the magnetosheath can be
expected to develop when and if the flow speed passes through the slow mode.
The
ISEE-1 magnetosheath data from the subsolar region presented in this
paper appears to concur with the predictions of such a transition.
Figure 3 in Russell's paper illustrates an example of this data. The
magnetic field clock angle should remain constant on both sides of the
fast shock, shown in the figure.
However, the apparent rotation and density jump between 4:10 and
4:36 Universal Time seems to correspond
with a slow mode shock.
These slow mode transitions are present about 2/3 of the time, are
highly variable, and are associated with high magnetic field rotations
and density increases.
A ratio of one earth radius per hour provides a very
approximate distance scale in Figure 3. This means that the main current
layer is around half an earth radius away from the standing mode, whose
thickness is also in the area of half an earth radius.
The density enhancements are more frequently present for a low beta
magnetosheath, and could possibly be a transient phenomenon [Yan and
Lee, 1994]. Their observations are strongly associated with the
presence of slow mode shocks, which confirm predictions of their existence.
Return to "The Structure of the Magnetosphere" by
C. T. Russell.