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| Titel |
Scale sizes of intense auroral electric fields observed by Cluster |
| VerfasserIn |
T. Johansson, G. Marklund, T. Karlsson, S. Liléo, P.-A. Lindqvist, H. Nilsson, S. Buchert |
| 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. 11 ; Nr. 25, no. 11 (2007-11-29), S.2413-2425 |
| Datensatznummer |
250015950
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| Publikation (Nr.) |
 copernicus.org/angeo-25-2413-2007.pdf |
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| Zusammenfassung |
The scale sizes of intense (>0.15 V/m, mapped to the
ionosphere), high-altitude (4–7 RE geocentric distance)
auroral electric fields (measured by the Cluster EFW instrument)
have been determined in a statistical study. Monopolar and bipolar
electric fields, and converging and diverging events, are
separated. The relations between the scale size, the intensity and
the potential variation are investigated.
The electric field scale sizes are further compared with the scale
sizes and widths of the associated field-aligned currents (FACs).
The influence of, or relation between, other parameters (proton
gyroradius, plasma density gradients, and geomagnetic activity),
and the electric field scale sizes are considered.
The median scale sizes of these auroral electric field structures
are found to be similar to the median scale sizes of the
associated FACs and the density gradients (all in the range
4.2–4.9 km) but not to the median proton gyroradius or the proton
inertial scale length at these times and locations (22–30 km).
(The scales are mapped to the ionospheric altitude for reference.)
The electric field scale sizes during summer months and high
geomagnetic activity (Kp>3) are typically 2–3 km, smaller than
the typical 4–5 km scale sizes during winter months and low
geomagnetic activity (Kp≤3), indicating a dependence on
ionospheric conductivity. |
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