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GEOPHYSICAL RESEARCH LETTERS, VOL. 32, L22102, doi:10.1029/2005GL023515, 2005

Analysis of the October 3–7 2000 GEM storm with the WINDMI model

W. Horton

Institute for Fusion Studies, University of Texas, Austin, Texas, USA


E. Spencer

Institute for Fusion Studies, University of Texas, Austin, Texas, USA


I. Doxas

Center for Integrated Plasma Studies, University of Colorado, Boulder, Colorado, USA


J. Kozyra

Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, Michigan, USA


Abstract

The 8 dimensional physics model WINDMI is used to analyze the October 3–7, 2000 geomagnetic storm using solar wind input data from the ACE satellite. This period was chosen because it contains an extended interval of well-defined and quasi-periodic auroral activations called sawtooth oscillations, a phenomena whose relationship to substorm processes and to upstream solar wind drivers is still under debate. The question of whether multiple sawtooth oscillations are triggered by periodic upstream solar wind features or by internal magnetospheric processes is addressed. The model predicts both the occurrence of 8 auroral activations identified as sawtooth events during the 24 hour period on the 4th of October, in agreement with the measured AL index, and also an earlier multiple sawtooth interval on the 3rd of October, in agreement with the measured AL index. These intervals occur during steady but moderate solar wind IMF Bz values and the periodicity of the sawtooth events was not directly related to any periodic features in the upstream solar wind. The model also predicts the geomagnetic Dst index through the main and recovery phase of the storm.

Received 18 May 2005; accepted 10 October 2005; published 17 November 2005.

Index Terms: 2730 Magnetospheric Physics: Magnetosphere: inner; 2721 Magnetospheric Physics: Field-aligned currents and current systems (2409); 2736 Magnetospheric Physics: Magnetosphere/ionosphere interactions (2431); 2740 Magnetospheric Physics: Magnetospheric configuration and dynamics.

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Citation: Horton, W., E. Spencer, I. Doxas, and J. Kozyra (2005), Analysis of the October 3–7 2000 GEM storm with the WINDMI model, Geophys. Res. Lett., 32, L22102, doi:10.1029/2005GL023515.