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The response of the magnetosphere to the passage of a coronal mass ejection on March 20−21 1990

Annales Geophysicae. 1997;15:671-684 DOI 10.1007/s00585-997-0671-4

 

Journal Homepage

Journal Title: Annales Geophysicae

ISSN: 0992-7689 (Print); 1432-0576 (Online)

Publisher: Copernicus Publications

Society/Institution: European Geosciences Union (EGU)

LCC Subject Category: Science: Physics: Geophysics. Cosmic physics

Country of publisher: Germany

Language of fulltext: English

Full-text formats available: PDF, XML

 

AUTHORS


J. R. Taylor (Department of Physics and Astronomy, University of Leicester, University Road, Leicester UK)

M. Lester (Department of Physics and Astronomy, University of Leicester, University Road, Leicester UK)

T. K. Yeoman (Department of Physics and Astronomy, University of Leicester, University Road, Leicester UK)

B. A. Emery (High Altitude observatory, NCAR, POB 3000, Boulder, Colorado, USA)

D. J. Knipp (Department of Physics, US Airforce Academy, Colorado, USA)

D. Orr (Department of Physics, University of York, York, UK)

S. I. Solovyev (Institute of Cosmophysical Research and Aeronomy, 31 Lenin Avenue., 677891, Yakutsk, Russia)

T. J. Hughes (Herzberg Institute of Astrophysics, National Research Council of Canada, Ottawa, Ontario, Canada)

H. Lühr (Institut für Geophysik und Meteorologie, Technische Universität, Braunschweig, D-38106 Braunschweig, Germany)

EDITORIAL INFORMATION

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Time From Submission to Publication: 28 weeks

 

Abstract | Full Text

The geomagnetic response to the passage of a coronal mass ejection (CME) is studied. The passage of the CME resulted in a storm sudden commencement (SSC) at 2243 UT on March 20 1990 with disturbed magnetic activity during the following 24 h. The auroral, sub-auroral and equatorial magnetic response to the southward turning at 1314 (±5) UT on March 21 and the equatorial response to the southward turning associated with the SSC on 20 March are discussed in terms of existing models. It is found that the auroral and sub-auroral response to the southward turning associated with the SSC is a factor 2 or more quicker than normal due to the shock in the solar wind dynamic pressure. The low-latitude response time to the southward turning, characterised by <i>Dst</i> and the magnetopause current corrected <i>Dst</i>*, is unaffected by the shock. <i>Dst</i> and <i>Dst</i>*, characteristic of the equatorial magnetic field, responded to the 1314 (±5) UT southward turning prior to the first observed substorm expansion phase onset, suggesting that a dayside loading process was responsible for the initial enhancement in the ring current rather than nightside particle injection. The response time of the auroral and sub-auroral magnetic field to the southward turning at 1314 (±5) UT on March 21 is measured at a variety of longitudes and latitudes. The azimuthal propagation velocity of the response to the southward turning varied considerably with latitude, ranging from ~8 km s<sup>–1</sup> at 67°N to ~4 km s<sup>–1</sup> at 55°N. The southward velocity of the equatorward boundary of the northern polar convection pattern has been measured. This velocity was ~1.2 km s<sup>–1</sup> at 1600 MLT, although there was evidence that this may vary at different local times.