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| Titel |
Storm enhanced density: magnetic conjugacy effects |
| VerfasserIn |
J. C. Foster, W. Rideout |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 25, no. 8 ; Nr. 25, no. 8 (2007-08-29), S.1791-1799 |
| Datensatznummer |
250015896
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| Publikation (Nr.) |
 copernicus.org/angeo-25-1791-2007.pdf |
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| Zusammenfassung |
In the early phases of a geomagnetic storm, the low and mid-latitude
ionosphere are greatly perturbed. Large SAPS electric fields map earthward
from the perturbed ring current overlapping and eroding the outer
plasmasphere and mid-latitude ionosphere, drawing out extended plumes of
storm enhanced density (SED). We use combined satellite and ground-based
observations to investigate the degree of magnetic conjugacy associated with
specific features of the stormtime ionospheric perturbation. We find that
many ionospheric disturbance features exhibit degrees of magnetic conjugacy
and simultaneity which implicate the workings of electric fields. TEC
enhancements on inner-magnetospheric field lines at the base of the SED
plumes exhibit localized and longitude-dependent features which are not
strictly magnetic conjugate. The SED plumes streaming away from these source
regions closely follow magnetic conjugate paths. SED plumes can be used as a
tracer of the location and strength of disturbance electric fields. The SED
streams of cold plasma from lower latitudes enter the polar caps near noon,
forming conjugate tongues of ionization over the polar regions. SED plumes
exhibit close magnetic conjugacy, confirming that SED is a convection
electric field dominated effect. Several conclusions are reached:
1) The SED plume occurs in magnetically-conjugate regions in both
hemispheres.
2) The position of the sharp poleward edge of the SED plume is closely
conjugate.
3) The SAPS electric field is observed in magnetically conjugate regions
(SAPS channel).
4) The strong TEC enhancement at the base of the SED plume in the north
American sector is more extensive than in its magnetic conjugate region.
5) The entry of the SED plume into the polar cap near noon, forming the
polar tongue of ionization (TOI), is seen in both hemispheres in
magnetically-conjugate regions. |
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