Excitation of transient lobe cell convection and auroral arc at the cusp poleward boundary during a transition of the interplanetary magnetic field from south to north
Item
Title (Dublin Core)
Excitation of transient lobe cell convection and auroral arc at the cusp poleward boundary during a transition of the interplanetary magnetic field from south to north
Description (Dublin Core)
We document the activation
of transient polar arcs emanating from the cusp within a 15 min long
intermediate phase during the transition from a standard two-cell convection
pattern, representative of a strongly southward interplanetary magnetic field (IMF),
to a "reverse" two-cell pattern, representative of strongly northward
IMF conditions. During the 2–3 min lifetime of the arc, its base in the cusp,
appearing as a bright spot, moved eastward toward noon by ~ 300 km. As the arc
moved, it left in its "wake" enhanced cusp precipitation. The polar
arc is a tracer of the activation of a lobe convection cell with clockwise
vorticity, intruding into the previously established large-scale distorted
two-cell pattern, due to an episode of localized lobe reconnection. The lobe
cell gives rise to strong flow shear (converging electric field) and an
associated sheet of outflowing field-aligned current, which is manifested by the
polar arc. The enhanced cusp precipitation represents, in our view, the
ionospheric footprint of the lobe reconnection process.<br><br><b>Key words. </b>Magnetospheric physics (auroral
phenomena; magnetopause, cusp, and boundary layers; plasma convection)
of transient polar arcs emanating from the cusp within a 15 min long
intermediate phase during the transition from a standard two-cell convection
pattern, representative of a strongly southward interplanetary magnetic field (IMF),
to a "reverse" two-cell pattern, representative of strongly northward
IMF conditions. During the 2–3 min lifetime of the arc, its base in the cusp,
appearing as a bright spot, moved eastward toward noon by ~ 300 km. As the arc
moved, it left in its "wake" enhanced cusp precipitation. The polar
arc is a tracer of the activation of a lobe convection cell with clockwise
vorticity, intruding into the previously established large-scale distorted
two-cell pattern, due to an episode of localized lobe reconnection. The lobe
cell gives rise to strong flow shear (converging electric field) and an
associated sheet of outflowing field-aligned current, which is manifested by the
polar arc. The enhanced cusp precipitation represents, in our view, the
ionospheric footprint of the lobe reconnection process.<br><br><b>Key words. </b>Magnetospheric physics (auroral
phenomena; magnetopause, cusp, and boundary layers; plasma convection)
Creator (Dublin Core)
P. E. Sandholt
C. J. Farrugia
S. W. H. Cowley
M. Lester
J.-C. Cerisier
Subject (Dublin Core)
Science
Q
Physics
QC1-999
Geophysics. Cosmic physics
QC801-809
Publisher (Dublin Core)
Copernicus Publications
Date (Dublin Core)
2001-05-01T00:00:00Z
Type (Dublin Core)
article
Identifier (Dublin Core)
10.5194/angeo-19-487-2001
0992-7689
1432-0576
https://doaj.org/article/404ba13a0d0a4de6acde9a2eac0a92a8
Source (Dublin Core)
Annales Geophysicae, Vol 19, Pp 487-493 (2001)
Language (Dublin Core)
EN
Relation (Dublin Core)
https://www.ann-geophys.net/19/487/2001/angeo-19-487-2001.pdf
https://doaj.org/toc/0992-7689
https://doaj.org/toc/1432-0576
Provenance (Dublin Core)
Journal Licence: CC BY