EISCAT/CRR.ES observations: Nightside ionospheric ion outflow and oxygen-rich substorm injections, Ann

• Main Authors: N. G. J. Gazey, M. Lockwood, M. Gr, C. H. Perry, P. N. Smith, S. Coles, A. D. Aylward, R. J. Bunting, H. Opgenoorth, B. Wilken
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 1996
• Subjects: EISCAT
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.694.9303; http://www.eiscat.rl.ac.uk/Members/mike/publications/pdfs/1996/140_Gazey_1032.pdf

Abstract. We present combined observations made near midnight by the EISCAT radar, all-sky cameras and the combined released and radiation efects satellite (CRRES) shortly before and during a substorm. In particular, we study a discrete, equatorward-drifting auroral arc, seen several degrees poleward of the onset region. The arc passes through the field-aligned beam of the EISCAT radar and is seen to be associated with a considerable upflow of ionospheric plasma. During the substorm, the CRRES satellite observed two major injections, 17 min apart, the second of which was dominated by O ` ions. We show that the observed arc was in a suitable location in both latitude and MLT to have fed O ` ions into the second injection and that the upward flux of ions asso-ciated with it was sufficient to explain the observed injec-tion. We interpret these data as showing that arcs in the nightside plasma-sheet boundary layer could be the source of O ` ions energised by a dipolarisation of the mid- and near-Earth tail, as opposed to ions ejected from the dayside ionosphere in the cleft ion fountain. 1