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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 15, issue 7
Ann. Geophys., 15, 918–924, 1997
https://doi.org/10.1007/s00585-997-0918-0
© European Geosciences Union 1997
Ann. Geophys., 15, 918–924, 1997
https://doi.org/10.1007/s00585-997-0918-0
© European Geosciences Union 1997

  31 Jul 1997

31 Jul 1997

E-region mid-latitude decametre irregularities observed at four radar frequencies. Experiment and first results

G. C. Hussey1, J. Delloue1, C. Haldoupis2, and A. Bourdillon3 G. C. Hussey et al.
  • 1Laboratoire de Physique de l'Exosphère, Université Pierre et Marie Curie, Paris, France
  • 2Physics Department, University of Crete, Iraklion, Crete, Greece
  • 3Laboratoire Radiocommunications, Université de Rennes 1, Rennes, France

Abstract. In this paper an experiment designed for multifrequency azimuthal Doppler-spectrum investigations of decametre-scale plasma irregularities in the mid-latitude E region is introduced and some preliminary results are presented. The observations were made with the high-frequency Valensole radar in the south of France. The radar operated in a multifrequency mode that allowed simultaneous measurements of Doppler spectra at the four frequencies of 9.23, 11.03, 12.71 and 16.09 MHz, which correspond to scatter from field-aligned irregularities with wavelengths of 16.2, 13.6, 11.8 and 9.3 m, respectively. In addition, a digital ionosonde was operating beneath a small part of the radar viewing region. The data show that lower-frequency echoes are stronger, more frequent and more spatially extended than higher-frequency ones, in general agreement with theory and rocket measurements. On the other hand, the preliminary analysis shows no pronounced differences of the Doppler spectrum with radar frequency. Some trends in the spectral moments do exist, however, which can be understood as the result of temporal and/or spatial mixing of backscatter from directly generated (primary) plasma waves by the gradient drift instability and secondary low-velocity waves. Finally, a close relation of mid-latitude coherent backscatter with patchy sporadic E-layers is present in the data, but the details of this relation remain unresolved.

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