 |
| Titel |
Characteristics of a stable arc based on FAST and MIRACLE observations |
| VerfasserIn |
P. Janhunen  , A. Olsson, O. Amm, K. Kauristie |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
0992-7689
|
| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 18, no. 2 ; Nr. 18, no. 2, S.152-160 |
| Datensatznummer |
250013903
|
| Publikation (Nr.) |
 copernicus.org/angeo-18-152-2000.pdf |
|
|
|
|
|
| Zusammenfassung |
A stable evening sector arc is studied using observations from
the FAST satellite at 1250 km altitude and the MIRACLE ground-based network,
which contains all-sky cameras, coherent radars (STARE), and magnetometers. Both
FAST and STARE observe a northward electric field region of about 200 km width
and a field magnitude of about 50 mV/m southward of the arc, which is a typical
signature for an evening-sector arc. The field-aligned current determined from
FAST electron and magnetometer data are in rather good agreement within the
arcs. Outside the arcs, the electron data misses the current carriers of the
downward FAC probably because it is mainly carried by electrons of smaller
energy than the instrument threshold. Studying the westward propagation speed of
small undulations associated with the arc using the all-sky cameras gives a
velocity of about 2 km/s. This speed is higher than the background ionospheric
plasma speed (about 1 km/s), but it agrees rather well with the idea originally
proposed by Davis that the undulations reflect an E × B motion in
the acceleration region. The ground magnetograms indicate that the main current
flows slightly south of the arc. Computing the ionospheric conductivity from
FAST electron data and using the ground magnetograms to estimate the current
yields an ionospheric electric field pattern, in rather good agreement with FAST
results.
Key words: Ionosphere (auroral ionosphere;
ionosphere-magnetosphere interactions) - Magnetospheric physics (auroral
phenomena) |
| |
|
| Teil von |
|
|
|
|
|
|
|
|