 |
| Titel |
Night-time sudden commencements observed by CHAMP and ground-based magnetometers and their relationship to solar wind parameters |
| VerfasserIn |
H. Lühr, K. Schlegel, T. Araki, M. Rother, M. Forster |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
0992-7689
|
| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 27, no. 5 ; Nr. 27, no. 5 (2009-05-04), S.1897-1907 |
| Datensatznummer |
250016508
|
| Publikation (Nr.) |
 copernicus.org/angeo-27-1897-2009.pdf |
|
|
|
|
|
| Zusammenfassung |
| We have studied 41 Sudden Commencements (SC) using simultaneous magnetic
field data from the CHAMP satellite and ground stations of the years 2000–2007.
They are all night time events, since the influence of ionospheric
currents on the SC is supposed to be minimal at night. This is confirmed by
our study for geomagnetic latitudes below ±40°. We further found
that the onset times of the SC signature at satellite altitude and on the
ground are the same within an uncertainty of 10 s and that the slopes of the
corresponding magnetic field variation are very similar. For magnetic
latitudes poleward of ±40° the amplitude of SCs increases both at
the satellite and on ground, probably a consequence of field-aligned
currents. CHAMP sometimes records small-scale magnetic variations different
from the ground, which can be explained by local ionospheric currents. We
also studied the relationship between the SC amplitude seen by CHAMP and the
corresponding abrupt solar wind dynamic pressure change, using ACE data. Our
results are compared with earlier studies using ground-based data and with
theoretical expectations. It turns out that the induction effect in the
Earth is quite small at low latitudes. Another important result is that the
magnetic signature near the Earth is over-proportionally reduced for weak SC
events. A discussion of accuracy and the uncertainty of our results
completes the paper. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|