Geoscience Reference
In-Depth Information
Fig. 2.
Possible current closure mechanisms at Mercury (after Grard
12
).
absence of collisions, the current flowing may be a Hall current arising from
E
B
drifting electrons. With this assumption the correlation is seen for
thesamecomponentsof
E
and
B
rather than for the orthogonal ones.
10
Figure 2 illustrates some of the possible current closure mechanisms at
Mercury.
×
2.6.
Magnetospheric compressibility
The compressibility of the magnetosphere under fluctuations is also related
to the conductivity of the planet. If the surface and body are non-conducting
the field lines are anchored in the dynamo region of the planet, whereas with
a perfectly conducting surface they would be anchored at the surface, thus
reducing the magnetospheric compressibility. For the intermediate case the
anchor depth would be frequency dependent and approximately given by
the condition that the magnetic Reynold's number be about unity. This
is yet another reason for trying to understand the nature of Mercury's
conductivity.
