Reference : Global morphology of substorm growth phases observed by the IMAGE-SI12 imager
Scientific congresses and symposiums : Poster
Physical, chemical, mathematical & earth Sciences : Space science, astronomy & astrophysics
http://hdl.handle.net/2268/101615
Global morphology of substorm growth phases observed by the IMAGE-SI12 imager
English
Blockx, Caroline mailto [Université de Liège - ULg > > Aquapôle >]
Gérard, Jean-Claude mailto [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Département d'astrophys., géophysique et océanographie (AGO) >]
Coumans, Valérie mailto [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP) >]
Hubert, Benoît mailto [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP) >]
Connors, Martin [> >]
2007
No
No
International
Annual meeting of the European Geoscience Union
April 2007
EGU
Vienna
Austra
[en] auroral substorms ; morphology ; ultraviolet
[en] Growth phases are observed to start from less than 30 minutes to over an hour before the substorm onset. The sector of maximum proton precipitation during the growth phase is generally located around 2200 MLT. It rapidly moves in local time by about 1.2 hour toward midnight at the time of the onset. The open magnetic flux increases by as much as a 33% during the growth phase. The mean value of the open flux at the end of the growth phase, immediately preceding the substorm, onset is about 0.74. GWb for substorms triggered by external (solar wind) factors and 0.67 GWb for non-triggered substorms. The open magnetic flux generally drops following the onset of triggered substorms but continues to increase for non-triggered events. We interpret this behavior as an indication that the rate of opening of closed field lines on the dayside can exceed that of the nightside reconnection after the onset in non-triggered substorms. By contrast, flux closure is more efficient while the flux opening rate drops in the case of externally triggered onset, so that the closure rate exceeds that of field line opening on the dayside. The rate of equatorward displacement is typically ~ 3 deg/hour. It is statistically correlated with the magnitude of the southward Bz component of the IMF measured by the ACE satellite. It is also correlated with transfer functions describing the efficiency of solar wind energy transfer which involve the transverse electric field carried by the solar wind.
The equatorward motion may be global, restricted to local time sectors or a combination of both. No nightside local time sector appears favored where the motion of the equatorial boundary would be more pronounced. The maximum displacement of the polar boundary is statistically located around midnight MLT.
Researchers ; Professionals
http://hdl.handle.net/2268/101615

There is no file associated with this reference.

Bookmark and Share SFX Query

All documents in ORBi are protected by a user license.