 |
| Titel |
Ionospheric convection during the magnetic storm of 20-21 March 1990 |
| VerfasserIn |
J. R. Taylor, T. K. Yeoman, Mark Lester, M. J. Buonsanto, J. L. Scali, J. M. Ruohoniemi, J. D. Kelly |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
0992-7689
|
| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 12, no. 12 ; Nr. 12, no. 12, S.1174-1191 |
| Datensatznummer |
250011247
|
| Publikation (Nr.) |
 copernicus.org/angeo-12-1174-1994.pdf |
|
|
|
|
|
| Zusammenfassung |
| We report on the response of high-latitude
ionospheric convection during the magnetic storm of March 20-21 1990. IMP-8
measurements of solar wind plasma and interplanetary magnetic field (IMF),
ionospheric convection flow measurements from the Wick and Goose Bay coherent
radars, EISCAT, Millstone Hill and Sondrestrom incoherent radars and three
digisondes at Millstone Hill, Goose Bay and Qaanaaq are presented. Two intervals
of particular interest have been identified. The first starts with a storm
sudden commencement at 2243 UT on March 20 and includes the ionospheric activity
in the following 7 h. The response time of the ionospheric convection to the
southward turning of the IMF in the dusk to midnight local times is found to be
approximately half that measured in a similar study at comparable local times
during more normal solar wind conditions. Furthermore, this response time is the
same as those previously measured on the dayside. An investigation of the
expansion of the polar cap during a substorm growth phase based on Faraday's law
suggests that the expansion of the polar cap was nonuniform. A subsequent
reconfiguration of the nightside convection pattern was also observed, although
it was not possible to distinguish between effects due to possible changes in By
and effects due to substorm activity. The second interval, 1200-2100 UT 21 March
1990, included a southward turning of the IMF which resulted in the Bz
component becoming -10 nT. The response time on the dayside to this change in
the IMF at the magnetopause was approximately 15 min to 30 min which is a factor
of ~2 greater than those previously measured at higher latitudes. A movement of
the nightside flow reversal, possibly driven by current systems associated with
the substorm expansion phases, was observed, implying that the nightside
convection pattern can be dominated by substorm activity. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|