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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 113, A05209, doi:10.1029/2007JA012624, 2008

Cluster observations of O+ escape in the magnetotail due to shock compression effects during the initial phase of the magnetic storm on 17 August 2001

E. Echer

Instituto Nacional de Pesquisas Espaciais, Sao Jose dos Campos, Sao Paulo, Brazil
Max-Planck-Institut für Sonnensystemforschung, Katlenburg-Lindau, Germany


A. Korth

Max-Planck-Institut für Sonnensystemforschung, Katlenburg-Lindau, Germany


Q.-G. Zong

Center for Space Physics, Boston University, Boston, Massachusetts, USA


M. Fra¨nz

Max-Planck-Institut für Sonnensystemforschung, Katlenburg-Lindau, Germany


W. D. Gonzalez

Instituto Nacional de Pesquisas Espaciais, Sao Jose dos Campos, Sao Paulo, Brazil


F. L. Guarnieri

Universidade do Vale do Paraiba, Sao Jose dos Campos, Sao Paulo, Brazil


S. Y. Fu

Institute of Space Physics and Technology, Peking University, Beijing, China


H. Reme

Centre d' Etude Spatiale des Rayonnements, Toulouse, France


Abstract

We study the O+ outflow into the magnetotail during the initial phase of the 17 August 2001 magnetic storm. Solar wind and magnetospheric data are used from instruments onboard ACE, WIND, and Cluster spacecraft. The interplanetary shock arrival at Earth caused a large compression of the magnetosphere. During this event, the Cluster spacecraft were crossing the plasma sheet boundary layer of the magnetotail. Thus this case study constitutes a unique opportunity to observe the magnetotail response to a shock driven storm with multiple S/C data. We observed a field aligned oxygen (O+) outflow in the plasma sheet boundary layer and a bidirectional O+ flux in the central plasma sheet. Using the Cluster multiple spacecraft data, we derived the O+ gradient and the escape rate into the magnetotail during the initial phase of the magnetic storm. We found an escape rate of 4.0 × 1024 O+ ions s−1 in the plasma sheet boundary layer of the magnetotail, which is about 20 times the O+ inflow into the ring current during an intense magnetic storm.

Received 2 July 2007; accepted 3 January 2008; published 10 May 2008.

Keywords: Geomagnetic storm; plasma sheet; magnetotail; oxygen outflow; magnetosphere.

Index Terms: 2744 Magnetospheric Physics: Magnetotail; 2764 Magnetospheric Physics: Plasma sheet; 2788 Magnetospheric Physics: Magnetic storms and substorms (7954); 2784 Magnetospheric Physics: Solar wind/magnetosphere interactions; 2431 Ionosphere: Ionosphere/magnetosphere interactions (2736).

Subscriber Access to Full Article (Nonsubscribers may purchase for $9.00, Includes print PDF, file size: 2495454 bytes)

Citation: Echer, E., A. Korth, Q.-G. Zong, M. Fra¨nz, W. D. Gonzalez, F. L. Guarnieri, S. Y. Fu, and H. Reme (2008), Cluster observations of O+ escape in the magnetotail due to shock compression effects during the initial phase of the magnetic storm on 17 August 2001, J. Geophys. Res., 113, A05209, doi:10.1029/2007JA012624.