Reference : Contributions of the driven process and the loading-unloading process during substorm...
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Earth sciences & physical geography
http://hdl.handle.net/2268/13392
Contributions of the driven process and the loading-unloading process during substorms: A study based on 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) > Labo de physique atmosphérique et planétaire (LPAP) >]
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) >]
Meurant, M. [> > > >]
2009
Journal of Geophysical Research
American Geophysical Union (AGU)
114
Yes (verified by ORBi)
International
0148-0227
Washington
[en] IMAGE satellite ; energy input ; magnetospheric processes ; substorm
[en] Substorm energetics has been shown to have two components, the "loading-unloading'' component releasing energy previously stored in the tail and the "directly driven'' component dissipating simultaneously fed solar wind energy. Previous studies disagree about the relative importance of each process. The SI12 spectral imager onboard the IMAGE satellite provides images of the Doppler-shifted Lyman alpha auroral emission at 121.8 nm every 2 min. It has been used to determine the auroral intensity during substorms, which may be compared to the solar wind characteristics and interplanetary magnetic field components before and/or after substorm onsets. In this study, we analyze 256 substorms between June 2000 and December 2002, which satisfy criteria relative to the viewing conditions. We compare the mean nightside intensity during the expansion phase with the magnetic open flux, the epsilon parameter, and other coupling functions (used as proxies of transfer of solar wind energy to the magnetosphere) integrated over the growth phase or the expansion phase. The mean auroral intensity during the expansion phase correlates well with coupling functions integrated over the growth phase. We also find that the correlation between the auroral precipitation during the expansion phase and the coupling functions integrated over the expansion phase is lower but still significant. This implies that, even though both mechanisms contribute to the energy precipitated during substorms, the loading-unloading process is statistically dominant.
Researchers ; Professionals ; Students
http://hdl.handle.net/2268/13392
10.1029/2008JA013280
http://www.agu.org/pubs/crossref/2009/2008JA013280.shtml

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