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| Titel |
The role of external triggers in flow shear arcs in the dayside aurora |
| VerfasserIn |
P. E. Sandholt, C. J. Farrugia |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 26, no. 8 ; Nr. 26, no. 8 (2008-08-04), S.2159-2177 |
| Datensatznummer |
250016176
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| Publikation (Nr.) |
 copernicus.org/angeo-26-2159-2008.pdf |
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| Zusammenfassung |
| In case studies we
relate dayside auroral transients
to IMF By-distorted plasma convection cells
based on high-resolution observations from the ground.
We selected three days
representing positive and negative IMF By conditions when
SuperDARN returned reliable dayside convection patterns in the
sector of our optical observations from
Ny Ålesund, Svalbard (76° MLAT).
We combine two perspectives on the dayside aurora,
the local and the global.
In the first we derive the fine-structure
of dayside precipitation/convection as a function of
magnetic latitude (MLAT) and magnetic local time (MLT),
which is necessary to understand the local M-I coupling
processes (Birkeland current structure). The
larger perspective (quasi-global dayside aurora)
may be used to shed light on the solar wind-magnetosphere
interconnection topology.
The auroral morphology consists of brightening events
and poleward moving auroral forms
(PMAFs) in the pre- and postnoon sectors longitudinally
separated by a band of strongly attenuated aurora near noon.
We find that the MLT-dependent spatial structure in the dayside aurora
(PMAFs/prenoon – "midday gap aurora" – PMAFs/postnoon)
which is present during stable IMF conditions
is altered by temporal structure during intervals of
IMF/solar wind plasma transients.
The focus is on the PMAF substructure (so-called "rebrightening forms")
which we identify as
dynamical plasma flow shear arcs (FSAs) in By-distorted dawn-
and dusk-centered convection cells in the close vicinity of the
cusp. |
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