An Ionospheric Drift Theory of Aurora and Airglow
An earlier theory of polar geomagnetic storms is extended to determine the drifts of neutral ionization (electrons and positive ions moving with the same velocity in a direction perpendicular to the current vector). The theory gives the system of ionospheric electric fields and this gives the drift...
| Published in: | Geophysical Journal International |
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| Main Author: | |
| Format: | Text |
| Language: | English |
| Published: |
Oxford University Press
1963
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| Subjects: | |
| Online Access: | http://gji.oxfordjournals.org/cgi/content/short/7/4/415 https://doi.org/10.1111/j.1365-246X.1963.tb07086.x |
| Summary: | An earlier theory of polar geomagnetic storms is extended to determine the drifts of neutral ionization (electrons and positive ions moving with the same velocity in a direction perpendicular to the current vector). The theory gives the system of ionospheric electric fields and this gives the drift pattern, strongest above the auroral zones but extending down to the equator. Ionospheric drifts are divided into “Pedersen drift” in the direction of the electric field E and Hall drift at right angles to E the former has a maximum value E/2B at about 120 km, the latter reaches a value E/B at about 180 km. A poleward drift of either type is associated with an upward drift and vice versa. Ions originally in the upper ionosphere above the north pole drift south along the 22 h meridian and also down into the lower ionosphere causing a great increase in ionization density at lower levels. In the auroral zone the Pedersen drift is away from the pole in the morning current cell and towards the pole in the afternoon cell. These motions are strongly divergent, in different ways in the two cells, and may lead to the formation of auroral curtains in the morning cell and of more diffuse auroral forms in the afternoon cell. Localized concentrations of ionization in the auroral zone may have secondary effects, (a) By interfering with the magnetospheric motions they may cause precipitation of geomagnetically trapped ions, (b) They may react on the magnetospheric motions more generally to cause large-scale changes in these motions and hence in the morphology of magnetic storms, (c) They may cause ionospheric winds. The theory is extended to include drift motions between the auroral zones and the equator where it may be relevant to airglow, sporadic E and other ionospheric phenomena. |
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