 |
| Titel |
Cosmic radio-noise absorption bursts caused by solar wind shocks |
| VerfasserIn |
A. Osepian, S. Kirkwood  |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
0992-7689
|
| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 22, no. 8 ; Nr. 22, no. 8 (2004-09-07), S.2973-2987 |
| Datensatznummer |
250014979
|
| Publikation (Nr.) |
 copernicus.org/angeo-22-2973-2004.pdf |
|
|
|
|
|
| Zusammenfassung |
| Bursts of cosmic noise absorption observed at times of sudden commencements
(SC) of geomagnetic storms are examined. About 300SC events in absorption
for the period 1967-1990 have been considered. It is found that the response
of cosmic radio-noise absorption to the passage of an interplanetary shock
depends on the level of the planetary magnetic activity preceding the SC
event and on the magnitude of the magnetic field perturbation associated
with the SC (as measured in the equatorial magnetosphere). It is shown that
for SC events observed against a quiet background (Kp<2), the effects of
the SC on absorption can be seen only if the magnitude of the geomagnetic
field perturbation caused by the solar wind shock exceeds a threshold value
ΔBth. It is further demonstrated that the existence of this
threshold value, ΔBth, deduced from experimental data, can be
related to the existence of a threshold for exciting and maintaining the
whistler cyclotron instability, as predicted by quasi-linear theory. SC
events observed against an active background (Kp<2) are accompanied by
absorption bursts for all magnetic field perturbations, however small. A
quantitative description of absorption bursts associated with SC events is
provided by the whistler cyclotron instability theory. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|