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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 16, issue 7
Ann. Geophys., 16, 764–774, 1998
https://doi.org/10.1007/s00585-998-0764-8
© European Geosciences Union 1998
Ann. Geophys., 16, 764–774, 1998
https://doi.org/10.1007/s00585-998-0764-8
© European Geosciences Union 1998

  31 Jul 1998

31 Jul 1998

Interhemispheric contrasts in the ionospheric convection response to changes in the interplanetary magnetic field and substorm activity: a case-study

B. A. Shand1, T. K. Yeoman1, R. V. Lewis2, R. A. Greenwald3, and M. R. Hairston4 B. A. Shand et al.
  • 1Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH, UK
    e-mail: yxo@ion.le.ac.uk
  • 2NERC, British Antarctic Survey, Madingley Road, Cambridge, CB3 OET, UK
  • 3Johns Hopkins University, Applied Physics Laboratory, Laurel, MD 20707, USA
  • 4Center for Space Sciences, The University of Texas at Dallas, Richardson, Texas, USA

Abstract. Interhemispheric contrasts in the ionospheric convection response to variations of the interplanetary magnetic field (IMF) and substorm activity are examined, for an interval observed by the Polar Anglo-American Conjugate Experiment (PACE) radar system between ~1600 and ~2100 MLT on 4 March 1992. Representations of the ionospheric convection pattern associated with different orientations and magnitudes of the IMF and nightside driven enhancements of the auroral electrojet are employed to illustrate a possible explanation for the contrast in convection flow response observed in radar data at nominally conjugate points. Ion drift measurements from the Defence Meteorological Satellite Program (DMSP) confirm these ionospheric convection flows to be representative for the prevailing IMF orientation and magnitude. The location of the fields of view of the PACE radars with respect to these patterns suggest that the radar backscatter observed in each hemisphere is critically influenced by the position of the ionospheric convection reversal boundary (CRB) within the radar field of view and the influence it has on the generation of the irregularities required as scattering targets by high-frequency coherent radar systems. The position of the CRB in each hemisphere is strongly controlled by the relative magnitudes of the IMF Bz and By components, and hence so is the interhemispheric contrast in the radar observations.

Key words. Magnetospheric physics · Auroral phenomena · Magnetosphere-ionosphere interactions · Storms and substorms

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