Article (Scientific journals)
A superposed epoch analysis of auroral evolution during substorms: Local time of onset region
Milan, S. E.; Grocott, A.; Hubert, Benoît
2010In Journal of Geophysical Research. Space Physics, 115
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Keywords :
Magnetospheric Physics: Substorms; Magnetospheric Physics: Magnetospheric configuration and dynamics; Magnetospheric Physics: Auroral phenomena (2407)
Abstract :
[en] Previous workers have shown that the magnetic local time (MLT) of substorm onset depends on the prevailing east-west component of the interplanetary magnetic field (IMF). To investigate the influence of the onset MLT on the subsequent auroral response we perform a superposed epoch analysis of the auroral evolution during approximately 2000 substorms using observations from the FUV instrument on the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) spacecraft. We subdivide the substorms by onset latitude and onset local time before determining average auroral images before and after substorm onset, for both electron and proton aurorae. We find that during the growth phase there is preexisting auroral emission in the MLT sector of the subsequent onset. After onset the auroral bulge expands eastward and westward, but remains centered on the onset sector. Approximately 30 min after onset, during the substorm recovery phase, the peaks in electron and proton auroral emission move into the postnoon and prenoon sectors, respectively, reflecting the “average” auroral precipitation patterns determined by previous studies. Superposed epoch analysis of the interplanetary magnetic field for the substorms under study suggests that the B[SUB]Y[/SUB] component of the IMF must be biased toward positive or negative values for up to a day prior to onset for the onset MLT to be influenced.
Disciplines :
Space science, astronomy & astrophysics
Physics
Earth sciences & physical geography
Author, co-author :
Milan, S. E.;  Department of Physics and Astronomy, University of Leicester, Leicester, UK) ; AB(Department of Physics and Astronomy, University of Leicester, Leicester, UK) ; AC(Laboratory of Planetary and Atmospheric Physics, University of Liege, Liege, Belgium
Grocott, A.
Hubert, Benoît  
Language :
English
Title :
A superposed epoch analysis of auroral evolution during substorms: Local time of onset region
Publication date :
01 October 2010
Journal title :
Journal of Geophysical Research. Space Physics
ISSN :
2169-9380
eISSN :
2169-9402
Publisher :
American Geophysical Union (AGU), Washington, United States - District of Columbia
Volume :
115
Peer reviewed :
Peer Reviewed verified by ORBi
Available on ORBi :
since 01 March 2011

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