Substorm Onset and the Possible Role of O+ IONS Flowing out during Pseudo-Breakup Auroras

George K Parks1, Ensang Lee2, Matthew O Fillingim3, Suiyan Fu4, Yanbon Cui5 and Jinhy Hong2, (1)University of California Berkeley, Berkeley, United States, (2)Kyung Hee University, School of Space Research, Yongin, South Korea, (3)University of California Berkeley, Space Sciences Laboratory, Berkeley, United States, (4)Peking University, School of Earth and Space Sciences, Beijing, China, (5)Peking University, Beijing, China
Abstract:
An isolated substorm onset event that occurred on 14 February 2001 was recorded by the WIC on IMAGE. WIC observed an enhanced electron precipitation region that grew out of a pseudo-breakup auroral spot at the poleward boundary that moved southward and activitated an aurora. An isolated substorm onset was triggered when the pseudo-breakup region connected to the activitated aurora at the lower boundary. This observation is a global scale phenomenon, whose behavior is similar but also different from observations of north-south motion at smaller localized scales that precede the onset of substorms (Nishimura et al., 2010). Fortuitously, Cluster during this pseudo-break auroral activity, detected escape of low energy (20-50 eV) field-aligned O+ ions. The triggered onset was accompanied by the escape of more energetic O+ (80 eV -300 eV) ions. Our observations suggest that the escaping O+ ions during pseudo-breakup auroras may be the seed for the onset of isolated substorms needed in some simulation models (Winglee and Harnett, 2010).
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