THE QUADRUPOLE IONOSPHERE
H. Rishbeth
Department of Physics, University,
Southampton S09 5NH England
The paper discusses the principal features that might exist in the terrestrial ionosphere if the
geomagnetic field were to assume a quadrupole form during a magnetic polarity reversal. Twoi
possible configurations are considered, the “axial quadrupole” (Fig. 1) and the “lateral
quadrupole” (Fig. 2). Interesting phenomena are anticipated in “magnetic equatorial” regions
where the field is horizontal, and fast magnetospherically-driven plasma convection might occur at
latitudes where the field is steeply inclined.
The general effect of changes of field strength on conductivity is considered; a weaker field
raises the ionospheric conducting layer and enhances the conductivity; a stronger field lowers the
height of the conducting layer and decreases the conductivity.
375
o\
SUN
* Plasmapause
Field line
< Thermospheric wind
— — C Plasma convection
Auroral zone
NORTH POLAR CAP
/
^ £>/
NORTH - POLAR
AURORAL ZONE
NORTH MIDLATITUOE EQUATOR
NORTH TROPICAL AURORAL ZONE
TROPICAL CONVECTION ZONE
SOUTH TROPICAL AURORAL ZONE
■SOUTH MIDLATITUDE EQUATOR
SOUTH POLAR
AURORAL ZONE
SOUTH POLAR CAP
Figure 1.
O Neutral axis
* Plasmapause
— - Field line
Thermospheric wind
Plasma convection
Auroral zone
Figure 2.
