Very High-Altitude Aurora Observations With The Solar Mass Ejection Imager

J. Geophys. Res. 110, 7230−7247, 2005

Very High-Altitude Aurora Observations With The Solar Mass Ejection Imager

D.R. Mizuno
Inst. for Scientific Research, Boston College, MA

A. Buffington
Center for Astrophysics and Space Sciences, Univ. California San Diego, CA

M.P. Cooke and C.J. Eyles
School of Physics and Astronomy, Univ. Birmingham, UK

P. Hick
Center for Astrophysics and Space Sciences, Univ. California San Diego, CA

P.E. Holladay
Air Force Research Lab., Space Vehicles Directorate, Hanscom AFB, MA

B.V. Jackson
Center for Astrophysics and Space Sciences, Univ. California San Diego, CA

J.C. Johnston
Air Force Research Lab., Space Vehicles Directorate, Hanscom AFB, MA

T.A. Kuchar
Inst. for Scientific Research, Boston College, MA.

J.B. Mozer, S.D. Price and R.R. Radick
Air Force Research Lab., Space Vehicles Directorate, Hanscom AFB, MA

G.M. Simnett
School of Physics and Astronomy, Univ. Birmingham, UK

D. Sinclair
Air Force Research Lab., Space Vehicles Directorate, Hanscom AFB, MA

S.J. Tappin
School of Physics and Astronomy, Univ. Birmingham, UK

D.F. Webb
Inst. for Scientific Research, Boston College, MA

Abstract

The Solar Mass Ejection Imager (SMEI) is a sensitive satellite-mounted heliospheric scanning instrument which assembles an approximately all-sky image in red-biased visible light once per orbit. Its lines of sight pass obliquely through the topside ionosphere and magnetosphere. We present serendipitous observations of a visual phenomenon detected at high altitudes (> 840 km) over the auroral zones and polar caps. The phenomenon is observed in two basic forms. The first, and more common, are periods of brief (1-3 minutes), nearly uniform illumnination of the imager's field-of-view, which we interpret as transits of the satellite through a luminous medium. The second appear as localized filamentary structures, which we interpret as columns of luminous material, viewed from a distance, possibly extending to visible altitudes of 2000 km or higher. More than 1000 occurences of these phenomena were recorded during the first full year of operations. These observations are well correlated in brightness and frequency with periods of enhanced geomagnetic activity.