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| Titel |
Howthe IMF By induces a By component in the closed magnetosphere and how it leads to asymmetric currents and convection patterns in the two hemispheres |
| VerfasserIn |
Paul Tenfjord, Nikolai Østgaard, Kristian Snekvik, Jone Reistad, Karl Magnus Laundal, Stein Haaland, Steve Milan |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250125273
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| Publikation (Nr.) |
 EGU/EGU2016-4835.pdf |
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| Zusammenfassung |
| We describe the effects of the interplanetary magnetic field (IMF) By component on the
coupling between the solar wind and magnetosphere-ionosphere system using AMPERE
observations and MHD simulations. We show how By is induced on closed magnetospheric
field lines on both the dayside and nightside. The magnetosphere imposes asymmetric forces
on the ionosphere, and the effects on the ionospheric flow are characterized by distorted
convection cell patterns, often referred to as “banana” and “orange” cell patterns. The flux
asymmetrically added to the lobes results in a nonuniform induced By in the closed
magnetosphere. We present a mechanism that predicts asymmetric Birkeland currents at
conjugate foot points. Asymmetric Birkeland currents are created as a consequence of
y directed tension contained in the return flow. Associated with these currents,
we expect aurora and fast localized ionospheric azimuthal flows present in one
hemisphere but not necessarily in the other. We present a statistical study where we show
that these processes should occur on timescales of about 30 minutes after the IMF
By has arrived at the magnetopause. We also present an event with simultaneous
global imaging of the aurora and SuperDARN measurements from both hemisphere.
The event is interpreted as an example of the of the proposed asymmetric current
mechanism. |
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