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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 18, issue 1
Ann. Geophys., 18, 99–110, 2000
© European Geosciences Union 2000
Ann. Geophys., 18, 99–110, 2000
© European Geosciences Union 2000

  31 Jan 2000

31 Jan 2000

Multi-instrument observations of the electric and magnetic field structure of omega bands

J. A. Wild1, T. K. Yeoman1, P. Eglitis3,2, and H. J. Opgenoorth4,3 J. A. Wild et al.
  • 1Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH, UK
  • 2Department of Astronomy, Uppsala University, St. Olofsgatan 10, Box 256, S-751 05 Uppsala, Sweden
  • 3Finnish Meteorological Institute, Box 503, SF-00101, Helsinki, Finland
  • 4Swedish Institute of Space Physics, Uppsala Division, S-755 91 Uppsala, Sweden
  • Correspondence to: J. A. Wild
  • E-mail:

Abstract. High time resolution data from the CUTLASS Finland radar during the interval 01:30-03:30 UT on 11 May, 1998, are employed to characterise the ionospheric electric field due to a series of omega bands extending ~5° in latitude at a resolution of 45 km in the meridional direction and 50 km in the azimuthal direction. E-region observations from the STARE Norway VHF radar operating at a resolution of 15 km over a comparable region are also incorporated. These data are combined with ground magnetometer observations from several stations. This allows the study of the ionospheric equivalent current signatures and height integrated ionospheric conductances associated with omega bands as they propagate through the field-of-view of the CUTLASS and STARE radars. The high-time resolution and multi-point nature of the observations leads to a refinement of the previous models of omega band structure. The omega bands observed during this interval have scale sizes ~500 km and an eastward propagation velocity ~0.75 km s-1. They occur in the morning sector (~05 MLT), simultaneously with the onset/intensification of a substorm to the west during the recovery phase of a previous substorm in the Scandinavian sector. A possible mechanism for omega band formation and their relationship to the substorm phase is discussed..

Key words. Ionosphere (auroral ionosphere; electric fields and currents) · Magnetospheric physics (magnetosphere-ionosphere interactions)

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