 |
| Titel |
Interhemispheric differences and solar cycle effects of the high-latitude ionospheric convection patterns deduced from Cluster EDI observations |
| VerfasserIn |
Matthias Förster, Stein Haaland |
| Konferenz |
EGU General Assembly 2015
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250109019
|
| Publikation (Nr.) |
 EGU/EGU2015-8879.pdf |
|
|
|
|
|
| Zusammenfassung |
| Here, we present a study of ionospheric convection at high latitudes that is based on
satellite measurements of the Electron Drift Instrument (EDI) on-board the Cluster
satellites, which were obtained over a full solar cycle (2001-2013). The mapped drift
measurements are covering both hemispheres and a variety of different solar wind and
interplanetary magnetic field (IMF) conditions. The large amount of data allows us to
perform more detailed statistical studies. We show that flow patterns and polar cap
potentials can differ between the two hemispheres on statistical average for a given IMF
orientation. In particular, during southward directed IMF conditions, and thus enhanced
energy input from the solar wind, we find that the southern polar cap has a higher
cross polar cap potential. We also find persistent north-south asymmetries which
cannot be explained by external drivers alone. Much of these asymmetries can
probably be explained by significant differences in the strength and configuration of
the geomagnetic field between the Northern and Southern Hemisphere. Since the
ionosphere is magnetically connected to the magnetosphere, this difference will also
be reflected in the magnetosphere in the form of different feedback from the two
hemispheres. Consequently, local ionospheric conditions and the geomagnetic field
configuration are important for north-south asymmetries in large regions of geospace.
The average convection is higher during periods with high solar activity. Although
local ionospheric conditions may play a role, we mainly attribute this to higher
geomagnetic activity due to enhanced solar wind - magnetosphere interactions. |
|
|
|
|
|
|