 |
| Titel |
Comparison of solar wind driving of the aurora in the two hemispheres due to the solar wind dynamo |
| VerfasserIn |
Jone Peter Reistad, Nikolai Østgaard, Karl Magnus Laundal, Stein Haaland, Paul Tenfjord, Kjellmar Oksavik |
| Konferenz |
EGU General Assembly 2014
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250094250
|
| Publikation (Nr.) |
 EGU/EGU2014-9652.pdf |
|
|
|
|
|
| Zusammenfassung |
| Event studies of simultaneous global imaging of the aurora in both hemispheres have
suggested that an asymmetry of the solar wind driving between the two hemispheres could
explain observations of non-conjugate aurora during specific driving conditions. North-South
asymmetries in energy transfer from the solar wind across the magnetopause is believed to
depend upon the dipole tilt angle and the x-component of the interplanetary magnetic field
(IMF). Both negative tilt (winter North) and negative IMF Bx is expected to enhance the
efficiency of the solar wind dynamo in the Northern Hemisphere. By the same token,
positive tilt and IMF Bx is expected to enhance the solar wind dynamo efficiency
in the Southern Hemisphere. We show a statistical study of the auroral response
from both hemispheres using global imaging where we compare results during both
favourable and not favourable conditions in each hemisphere. By this study we will
address the question of general impact on auroral hemispheric asymmetries by this
mechanism – the asymmetric solar wind dynamo. We use data from the Wideband
Imaging Camera on the IMAGE spacecraft which during its lifetime from 2000-2005
covered both hemispheres. To ease comparison of the two hemispheres, seasonal
differences in auroral brightness is removed as far as data coverage allows by only
using events having small dipole tilt angles. Hence, the IMF Bx is expected to be
the controlling parameter for the hemispheric preference of strongest solar wind
dynamo efficiency in our dataset. Preliminary statistical results indicate the expected
opposite behaviour in the two hemispheres, however, the effect is believed to be weak. |
|
|
|
|
|
|