 |
| Titel |
The six-month line in geomagnetic long series |
| VerfasserIn |
J. L. Mouël, E. Blanter, M. Shnirman |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
0992-7689
|
| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 22, no. 3 ; Nr. 22, no. 3 (2004-03-19), S.985-992 |
| Datensatznummer |
250014816
|
| Publikation (Nr.) |
 copernicus.org/angeo-22-985-2004.pdf |
|
|
|
|
|
| Zusammenfassung |
Daily means of the horizontal components X (north) and Y (east) of the
geomagnetic field are available in the form of long series (several tens of years). Nine
observatories are used in the present study, whose series are among the longest. The
amplitudes of the 6-month and 1-year periodic variations are estimated using a simple but
original technique. A remarkably clear result emerges from the complexity of the
geomagnetic data: the amplitude of the 6-month line presents, in all observatories, the
same large variation (by a factor of 1.7) over the 1920–1990 time span, regular and quasi-sinusoidal.
Nothing comparable comes out for the annual line. The 6-month line results
from the modulation by an astronomical mechanism of a magnetospheric system of currents.
As this latter mechanism is time invariant, the intensity of the system of currents itself must
present the large variation observed on the 6-months variation amplitude. This variation
presents some similarities with the one displayed by recent curves of reconstructed solar
irradiance or the "Earth's temperature". Finally, the same analysis is applied to the aa magnetic
index.
Key words. Geomagnetism and paleomagnetism (time variations,
diurnal to secular). Magnetospheric physics (current
systems; polar cap phenomena) |
| |
|
| Teil von |
|
|
|
|
|
|
|
|