Journal cover Journal topic
Annales Geophysicae An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 1.490 IF 1.490
  • IF 5-year value: 1.445 IF 5-year
    1.445
  • CiteScore value: 2.9 CiteScore
    2.9
  • SNIP value: 0.789 SNIP 0.789
  • IPP value: 1.48 IPP 1.48
  • SJR value: 0.74 SJR 0.74
  • Scimago H <br class='hide-on-tablet hide-on-mobile'>index value: 88 Scimago H
    index 88
  • h5-index value: 21 h5-index 21
Volume 20, issue 10
Ann. Geophys., 20, 1631–1645, 2002
https://doi.org/10.5194/angeo-20-1631-2002
© Author(s) 2002. This work is distributed under
the Creative Commons Attribution 3.0 License.
Ann. Geophys., 20, 1631–1645, 2002
https://doi.org/10.5194/angeo-20-1631-2002
© Author(s) 2002. This work is distributed under
the Creative Commons Attribution 3.0 License.

  31 Oct 2002

31 Oct 2002

SuperDARN radar HF propagation and absorption response to the substorm expansion phase

J. K. Gauld1, T. K. Yeoman1, J. A. Davies1, S. E. Milan1, and F. Honary2 J. K. Gauld et al.
  • 1Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH, UK
  • 2Department of Communication Systems, University of Lancaster, Bailrigg, Lancaster, LA1 4YR, UK
  • Correspondence to: T. K. Yeoman
  • (tim.yeoman@ion.le.ac.uk)

Abstract. Coherent scatter HF ionospheric radar systems such as SuperDARN offer a powerful experimental technique for the investigation of the magnetospheric substorm. However, a common signature in the early expansion phase is a loss of HF backscatter, which has limited the utility of the radar systems in substorm research. Such data loss has generally been attributed to either HF absorption in the D-region ionosphere, or the consequence of regions of very low ionospheric electric field. Here observations from a well-instrumented isolated substorm which resulted in such a characteristic HF radar data loss are examined to explore the impact of the substorm expansion phase on the HF radar system. The radar response from the SuperDARN Hankasalmi system is interpreted in the context of data from the EIS-CAT incoherent scatter radar systems and the IRIS Riometer at Kilpisjarvi, along with calculations of HF absorption for both IRIS and Hankasalmi and ray-tracing simulations. Such a study offers an explanation of the physical mechanisms behind the HF radar data loss phenomenon. It is found that, at least for the case study presented, the major cause of data loss is not HF absorption, but changes in HF propagation conditions. These result in the loss of many propagation paths for radar backscatter, but also the creation of some new, viable propagation paths. The implications for the use of the characteristics of the data loss as a diagnostic of the substorm process, HF communications channels, and possible radar operational strategies which might mitigate the level of HF radar data loss, are discussed.

Key words. Ionosphere (ionosphere-magnetosphere interactions). Magnetospheric physics (storms and substorms). Radio science (radio wave propagation)

Publications Copernicus
Download
Citation