A proposed production model of rapid subauroral ion drifts and their relationship to substorm evolution
- NASA, Goddard Space Flight Center, Greenbelt, MD (United States)
- Univ. of Texas, Dallas (United States)
- Univ. of Iowa, Iowa City (United States)
The authors conduct a study of subauroral ion drifts (SAID), to examine their correlation with magnetic storms. By a SAID one means a latitudinally narrow band of westward drifting ions located on the equatorial side of the auroral oval in the evening ionosphere. They look at the relationship of SAID to various stages in the development of a substorm. Data comes from DE 1, which provided auroral images, DE 2 which measured ionospheric parameters by means of magnetometers, an ion drift meter, a low altitude plasma instrument, and a retarding potential analyzer, and measurements of particle injection made by instruments at geosynchronous orbit. Analysis of the data showed very low ion drifts or field aligned currents in regions equatorward of the auroral oval before or after substorms. After substorm onset ion drifts and field aligned currents were observed extending well equatorward of the oval. There was no clear drift spike in these observations suggesting a SAID. They never saw a SAID occuring within 30 minutes of substorm onset. In almost all observations of a SAID which could be correlated with the recovery phase of the substorm, the SAID was initiated in the recovery phase. The authors then propose a model to explain the SAID which draws upon a decrease in the conductivity in the E and F regions between the band of electron precipitation in the oval and the equatorward band of ion precipitation. Several factors play into this decrease, but its occurance allows the growth of large electric fields which can drive the plasma drift as the equatorward extent of the substorm expansion shrinks in the recovery phase.
- OSTI ID:
- 6499043
- Journal Information:
- Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 98:A4; ISSN JGREA2; ISSN 0148-0227
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
Ionospheric
& Magnetospheric Phenomena-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AURORAL OVAL
CHARGED-PARTICLE PRECIPITATION
CORRELATIONS
COUPLING
E REGION
EARTH ATMOSPHERE
ELECTRIC CONDUCTIVITY
ELECTRIC FIELDS
ELECTRICAL PROPERTIES
ELECTRON PRECIPITATION
F REGION
ION DRIFT
IONOSPHERE
MAGNETIC BAYS
MAGNETIC STORMS
PHYSICAL PROPERTIES
PLANETARY IONOSPHERES
PLASMA DRIFT