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| Titel |
Spatial distribution of conductances and currents associated with a north-south auroral form during a multiple-substorm period |
| VerfasserIn |
O. Amm, A. Pajunpää, U. Brandstrom |
| 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 ; 17, no. 11 ; Nr. 17, no. 11, S.1385-1396 |
| Datensatznummer |
250013832
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| Publikation (Nr.) |
 copernicus.org/angeo-17-1385-1999.pdf |
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| Zusammenfassung |
Using the method of characteristics to invert
ground-based data of the ground magnetic field disturbance and of the
ionospheric electric field, we obtain spatial distributions of ionospheric
conductances, currents, and field-aligned currents (FACs) associated with a
north-south auroral form that drifts westwards over northern Scandinavia around
2200 UT on December 2, 1977. This auroral form is one in a sequence of such
north-south structures observed by all-sky cameras, and appears 14 min after the
last of several breakups during that extremely disturbed night. Our analysis
shows that the ionospheric Hall conductance reaches values above 200 S in the
center of the form, and upward flowing FACs of up to 25 µA/m2 are
concentrated near its westward and equatorward edge. The strong upward flowing
FACs are fed by an area of more distributed, but still very strong
downward-flowing FACs northeastward of the auroral form. In contrast to the
conductances, the electric field is only slightly affected by the passage of the
form. We point out similarities and differences of our observations and results
to previously reported observations and models of 'auroral fingers',
'north-south aurora', and 'auroral streamers' which are suggested to be
ionospheric manifestations of bursty bulk flows in the plasma sheet.
Key words. Ionosphere (auroral ionosphere; electric
fields and currents) · Magnetospheric physics (magnetosphere · ionosphere
interactions) |
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