Magnetospheric reconnection driven by solar wind pressure fronts
Recent work has shown that solar wind dynamic pressure changes can have a dramatic effect on the particle precipitation in the high-latitude ionosphere. It has also been noted that the preexisting interplanetary magnetic field (IMF) orientation can significantly affect the resulting changes in t...
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doaj-cc8a3343e05148b39bb834fef6f7a3612020-11-24T23:06:47ZengCopernicus PublicationsAnnales Geophysicae0992-76891432-05762004-04-01221367137810.5194/angeo-22-1367-2004Magnetospheric reconnection driven by solar wind pressure frontsA. Boudouridis0E. Zesta1L. R. Lyons2P. C. Anderson3D. Lummerzheim4Department of Atmospheric Sciences, University of California, Los Angeles, USADepartment of Atmospheric Sciences, University of California, Los Angeles, USADepartment of Atmospheric Sciences, University of California, Los Angeles, USASpace Science Applications Laboratory, The Aerospace Corporation, Los Angeles, USAGeophysical Institute, University of Alaska, Fairbanks, USARecent work has shown that solar wind dynamic pressure changes can have a dramatic effect on the particle precipitation in the high-latitude ionosphere. It has also been noted that the preexisting interplanetary magnetic field (IMF) orientation can significantly affect the resulting changes in the size, location, and intensity of the auroral oval. Here we focus on the effect of pressure pulses on the size of the auroral oval. We use particle precipitation data from up to four Defense Meteorological Satellite Program (DMSP) spacecraft and simultaneous POLAR Ultra-Violet Imager (UVI) images to examine three events of solar wind pressure fronts impacting the magnetosphere under two IMF orientations, IMF strongly southward and IMF <i>B<sub>z</sub></i> nearly zero before the pressure jump. We show that the amount of change in the oval and polar cap sizes and the local time extent of the change depends strongly on IMF conditions prior to the pressure enhancement. Under steady southward IMF, a remarkable poleward widening of the oval at all magnetic local times and shrinking of the polar cap are observed after the increase in solar wind pressure. When the IMF <i>B<sub>z</sub></i> is nearly zero before the pressure pulse, a poleward widening of the oval is observed mostly on the nightside while the dayside remains unchanged. We interpret these differences in terms of enhanced magnetospheric reconnection and convection induced by the pressure change. When the IMF is southward for a long time before the pressure jump, open magnetic flux is accumulated in the tail and strong convection exists in the magnetosphere. The compression results in a great enhancement of reconnection across the tail which, coupled with an increase of magnetospheric convection, leads to a dramatic poleward expansion of the oval at all MLTs (dayside and nightside). For near-zero IMF <i>B<sub>z</sub></i> before the pulse the open flux in the tail, available for closing through reconnection, is smaller. This, in combination with the weaker magnetospheric convection, leads to a more limited poleward expansion of the oval, mostly on the nightside.<br><br> <b>Key words.</b> Magnetospheric physics (solar windmagnetosphere interactions; magnetospheric configuration and dynamics; auroral phenomena)https://www.ann-geophys.net/22/1367/2004/angeo-22-1367-2004.pdf |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
A. Boudouridis E. Zesta L. R. Lyons P. C. Anderson D. Lummerzheim |
spellingShingle |
A. Boudouridis E. Zesta L. R. Lyons P. C. Anderson D. Lummerzheim Magnetospheric reconnection driven by solar wind pressure fronts Annales Geophysicae |
author_facet |
A. Boudouridis E. Zesta L. R. Lyons P. C. Anderson D. Lummerzheim |
author_sort |
A. Boudouridis |
title |
Magnetospheric reconnection driven by solar wind pressure fronts |
title_short |
Magnetospheric reconnection driven by solar wind pressure fronts |
title_full |
Magnetospheric reconnection driven by solar wind pressure fronts |
title_fullStr |
Magnetospheric reconnection driven by solar wind pressure fronts |
title_full_unstemmed |
Magnetospheric reconnection driven by solar wind pressure fronts |
title_sort |
magnetospheric reconnection driven by solar wind pressure fronts |
publisher |
Copernicus Publications |
series |
Annales Geophysicae |
issn |
0992-7689 1432-0576 |
publishDate |
2004-04-01 |
description |
Recent work has shown that solar wind dynamic pressure changes
can have a dramatic effect on the particle precipitation in the
high-latitude ionosphere. It has also been noted that the preexisting
interplanetary magnetic field (IMF) orientation can significantly
affect the resulting changes in the size, location, and intensity
of the auroral oval. Here we focus on the effect of pressure pulses
on the size of the auroral oval. We use particle precipitation data
from up to four Defense Meteorological Satellite Program (DMSP)
spacecraft and simultaneous POLAR Ultra-Violet Imager (UVI) images
to examine three events of solar wind pressure fronts impacting the
magnetosphere under two IMF orientations, IMF strongly southward
and IMF <i>B<sub>z</sub></i> nearly zero before the pressure jump. We show that
the amount of change in the oval and polar cap sizes and the local
time extent of the change depends strongly on IMF conditions prior
to the pressure enhancement. Under steady southward IMF, a remarkable
poleward widening of the oval at all magnetic local times and
shrinking of the polar cap are observed after the increase in solar
wind pressure. When the IMF <i>B<sub>z</sub></i> is nearly zero before the pressure
pulse, a poleward widening of the oval is observed mostly on the
nightside while the dayside remains unchanged. We interpret these
differences in terms of enhanced magnetospheric reconnection and
convection induced by the pressure change. When the IMF is southward
for a long time before the pressure jump, open magnetic flux is
accumulated in the tail and strong convection exists in the
magnetosphere. The compression results in a great enhancement of
reconnection across the tail which, coupled with an increase of
magnetospheric convection, leads to a dramatic poleward expansion
of the oval at all MLTs (dayside and nightside). For near-zero IMF
<i>B<sub>z</sub></i> before the pulse the open flux in the tail, available for
closing through reconnection, is smaller. This, in combination
with the weaker magnetospheric convection, leads to a more limited
poleward expansion of the oval, mostly on the nightside.<br><br>
<b>Key words.</b> Magnetospheric physics (solar windmagnetosphere
interactions; magnetospheric configuration
and dynamics; auroral phenomena) |
url |
https://www.ann-geophys.net/22/1367/2004/angeo-22-1367-2004.pdf |
work_keys_str_mv |
AT aboudouridis magnetosphericreconnectiondrivenbysolarwindpressurefronts AT ezesta magnetosphericreconnectiondrivenbysolarwindpressurefronts AT lrlyons magnetosphericreconnectiondrivenbysolarwindpressurefronts AT pcanderson magnetosphericreconnectiondrivenbysolarwindpressurefronts AT dlummerzheim magnetosphericreconnectiondrivenbysolarwindpressurefronts |
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