Read Full Article (file size: 1884126 bytes)    Cited by

JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 107, NO. A9, 1251, doi:10.1029/2001JA007554, 2002

Interplanetary magnetic field control of afternoon-sector detached proton auroral arcs

J. L. Burch

Southwest Research Institute, San Antonio, Texas, USA

W. S. Lewis

Southwest Research Institute, San Antonio, Texas, USA

T. J. Immel

University of California, Berkeley, California, USA

P. C. Anderson

Aerospace Corporation, El Segundo, California, USA

H. U. Frey

University of California, Berkeley, California, USA

S. A. Fuselier

Lockheed Martin Advanced Technology Center, Palo Alto, California, USA

J.-C. Gérard

University of Liège, Liège, Belgium

S. B. Mende

University of California, Berkeley, California, USA

D. G. Mitchell

Applied Physics Laboratory, Johns Hopkins University, Laurel, Maryland, USA

M. F. Thomsen

Los Alamos National Laboratory, Los Alamos, New Mexico, USA

Abstract

Data from the Far Ultraviolet Imager (FUV) on the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) satellite show that subauroral proton arcs appear in the afternoon sector during geomagnetically disturbed periods when the interplanetary magnetic field rotates either from south to north or from west to east and when the magnetosphere is moderately compressed. Time series of proton aurora images show that the proton emissions are generally aligned along the equatorward part of the auroral oval. However, when interplanetary magnetic field (IMF) B_z changes from negative to positive the auroral oval contracts toward higher latitudes while the ring current proton precipitation remains stationary, resulting in a separation of several degrees between the latitude of the new oval position and a subauroral proton arc in the afternoon sector. A similar effect occurs when IMF B_y rotates from negative to positive, in which case the oval in the afternoon sector retreats toward higher latitudes, again leaving a separation between the oval and the subauroral proton arc of several degrees. Comparisons with low-altitude and geosynchronous satellite data show that the subauroral proton arc is caused by the precipitation of protons with energies from several keV to 30 keV and is likely associated with the existence of a plasmaspheric “drainage plume.” In contrast, the proton emissions along the main oval are caused by protons with energies generally less than 10 keV.

Published 25 September 2002.

Index Terms: 2704 Magnetospheric Physics: Auroral phenomena (2407); 2736 Magnetospheric Physics: Magnetosphere/ionosphere interactions; 2716 Magnetospheric Physics: Energetic particles, precipitating.

Read Full Article (file size: 1884126 bytes)    Cited by

Citation: Burch, J. L., W. S. Lewis, T. J. Immel, P. C. Anderson, H. U. Frey, S. A. Fuselier, J.-C. Gérard, S. B. Mende, D. G. Mitchell, and M. F. Thomsen (2002), Interplanetary magnetic field control of afternoon-sector detached proton auroral arcs, J. Geophys. Res., 107(A9), 1251, doi:10.1029/2001JA007554.

Copyright 2002 by the American Geophysical Union.