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Full text of "NASA Technical Reports Server (NTRS) 19860019858: The quadrupole ionosphere"

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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.