Auroral particles associated with a substorm brightening arc

Abstract

We investigated the characteristics of auroral precipitating particles associated with a brightened arc at a pseudo-substorm, using auroral images of a high-time resolution (0.25 s) all-sky TV camera, particle data from the DMSP F10 spacecraft, and high-latitude magnetograms. The arc brightening occurred at 0407 UT (∼20 MLT) on December 30, 1994, at Fort Smith (67 MLAT), Canada, coincident with high-latitude Pi 2 magnetic pulsations. The brightening appeared without expansion (pseudo-breakup), and Fort Smith was located duskside of the main onset region. From the simultaneous DMSP particle data, the brightened arc is found to correspond to an electron inverted-V structure near the equatorward edge of the electron precipitation region, suggesting the pseudo-breakup of the auroral substorm occurred in the inner part of the plasma sheet. Copyright 2005 by the American Geophysical Union.