Longitudinal development of a substorm brightening arc

K. Shiokawa; A. Ieda; A. Nakajima; K. Sakaguchi; R. Nomura; T. Aslaksen; M. Greffen; E. Spanswick; E. Donovan; S. B. Mende; J. McFadden; K.-H. Glassmeier; K.-H. Glassmeier; V. Angelopoulos; Y. Miyashita

doi:10.5194/angeo-27-1935-2009

Annales Geophysicae (May 2009)

Longitudinal development of a substorm brightening arc

K. Shiokawa,
A. Ieda,
A. Nakajima,
K. Sakaguchi,
R. Nomura,
T. Aslaksen,
M. Greffen,
E. Spanswick,
E. Donovan,
S. B. Mende,
J. McFadden,
K.-H. Glassmeier,
K.-H. Glassmeier,
V. Angelopoulos,
Y. Miyashita

Affiliations

K. Shiokawa: Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, Japan
A. Ieda: Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, Japan
A. Nakajima: Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, Japan
K. Sakaguchi: Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, Japan
R. Nomura: Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, Japan
T. Aslaksen: Department of Physics and Technology, University of Tromsø, Tromsø, Norway
M. Greffen: Department of Physics and Astronomy, University of Calgary, Calgary, Canada
E. Spanswick: Department of Physics and Astronomy, University of Calgary, Calgary, Canada
E. Donovan: Department of Physics and Astronomy, University of Calgary, Calgary, Canada
S. B. Mende: Space Science Laboratory, University of California Berkeley, CA, USA
J. McFadden: Space Science Laboratory, University of California Berkeley, CA, USA
K.-H. Glassmeier: Institut of Geopyhsics and extraterrtestrial Physics, TU Braunschweig, Germany
K.-H. Glassmeier: Max Planck Institut of Solar System Reserach, Katlenburg-Lindau, Germany
V. Angelopoulos: Institute of Geophysics and Planetary Physics, University of California at Los Angeles, Los Angeles, CA, USA
Y. Miyashita: Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan

DOI: https://doi.org/10.5194/angeo-27-1935-2009
Journal volume & issue: Vol. 27
pp. 1935 – 1940

Abstract

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We present simultaneous THEMIS-ground observations of longitudinal (eastward) extension of a substorm initial-brightening arc at Gillam (magnetic latitude: 65.6°) at 08:13 UT on 10 January 2008. The speed of the eastward arc extension was ~2.7 km/s. The extension took place very close to the footprints of the longitudinally separated THEMIS E and D satellites at ~12 RE. The THEMIS satellites observed field dipolarization, weak earthward flow, and pressure increase, which propagated eastward from E to D at a speed of ~50 km/s. The THEMIS A satellite, located at 1.6 RE earthward of THEMIS E, observed fluctuating magnetic field during and after the dipolarization. The THEMIS E/D observations suggest that the longitudinal extension of the brightening arc at substorm onset is caused by earthward flow braking processes which produce field dipolarization and pressure increase propagating in longitude in the near-earth plasma sheet.

Published in Annales Geophysicae

ISSN: 0992-7689 (Print); 1432-0576 (Online)
Publisher: Copernicus Publications
Country of publisher: Germany
LCC subjects: Science: Physics: Geophysics. Cosmic physics
Website: http://www.annales-geophysicae.net

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