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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 109, A03204, doi:10.1029/2003JA010287, 2004

Transient response of the Earth's magnetosphere to a localized density pulse in the solar wind: Simulation of traveling convection vortices

Ryuho Kataoka

Department of Geophysics, Tohoku University, Sendai, Japan


Hiroshi Fukunishi

Department of Geophysics, Tohoku University, Sendai, Japan


Shigeru Fujita

Meteorological College, Kashiwa, Japan


Takashi Tanaka

Graduate School of Sciences, Kyushu University, Fukuoka, Japan


Masahiro Itonaga

Faculty of Education, Yamaguchi University, Yamaguchi, Japan


Abstract

We investigate the transient response of the Earth's magnetosphere-ionosphere system to a localized density pulse in the solar wind using a magnetohydrodynamic simulation. The simulated ionospheric disturbances exhibit many properties similar to those observed during traveling convection vortices (TCVs). The simulated TCVs are driven by pairs of field-aligned currents. The generation mechanisms of the field-aligned currents in the magnetosphere are evaluated in terms of a wave equation of field-aligned currents. The source current is the inertial current associated with in-out plasma acceleration in the magnetosphere near the impact region. The inertial current is converted into the field-aligned current off from the equatorial region via the curvilinear effect. The inhomogeneous effect also generates the field-aligned current near the inner equatorial region where the sharp gradient of Alfvén speed exists.

Received 14 October 2003; accepted 23 January 2004; published 6 March 2004.

Index Terms: 2784 Magnetospheric Physics: Solar wind/magnetosphere interactions; 2708 Magnetospheric Physics: Current systems (2409); 2753 Magnetospheric Physics: Numerical modeling; 2724 Magnetospheric Physics: Magnetopause, cusp, and boundary layers.

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Citation: Kataoka, R., H. Fukunishi, S. Fujita, T. Tanaka, and M. Itonaga (2004), Transient response of the Earth's magnetosphere to a localized density pulse in the solar wind: Simulation of traveling convection vortices, J. Geophys. Res., 109, A03204, doi:10.1029/2003JA010287.