Spatial correlation of precipitating and trapped protons associated with an isolated substorm

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Abstract

[1] We compare the global morphology of medium energy (few keV) energetic neutral atom measurements from IMAGE/MENA with proton aurora measurements from IMAGE/FUV and in situ energetic proton data from LANL/SOPA before and during a magnetospheric substorm that commenced at 1245 UT on 19 September 2000. In the hours before substorm onset, several small auroral activations occurred at locations scattered around local midnight. The neutral atom (ENA) emissions increased continuously throughout the substorm growth phase, mimicking the pseudo-breakup behavior seen in the proton aurora and in situ energetic particle data. Half an hour before substorm onset, the rate of ENA flux increase accelerated. The substorm onset is characterized by a rapidly expanding proton aurora brightening starting near 22 magnetic local time. ENA fluxes continued to rise until 30 minutes after onset. Throughout the whole event the local time distribution of ENA and auroral emissions was remarkably similar.

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