Preprints
https://doi.org/10.5194/gi-2021-25
https://doi.org/10.5194/gi-2021-25

  13 Sep 2021

13 Sep 2021

Review status: a revised version of this preprint is currently under review for the journal GI.

On the determination of ionospheric electron density profiles using multi-frequency riometry

Derek McKay1,2, Juha Vierinen3, Antti Kero4, and Noora Partamies5,6 Derek McKay et al.
  • 1FINCA, Turku University, Turku, Finland
  • 2Metsähovi Radio Observatory, Aalto University, Kylmälä, Finland
  • 3Department of Physics and Technology, University of Tromsø, Norway
  • 4Sodankylä Geophysical Observatory, University of Oulu, Finland
  • 5UNIS University Centre in Svalbard, Svalbard, Norway
  • 6Birkeland Centre for Space Science, Bergen, Norway

Abstract. Radio wave absorption in the ionosphere is a function of electron density, collision frequency, radio wave polarisation, magnetic field and radio wave frequency. Several studies have used multi-frequency measurements of cosmic radio noise absorption to determine electron density profiles. Using the framework of statistical inverse problems, we investigated if an electron density altitude profile can be determined by using multi-frequency, dual-polarisation measurements. It was found that the altitude profile cannot be uniquely determined from a complete measurement of radio wave absorption for all frequencies and two polarisation modes. This implies that accurate electron density profile measurements cannot be ascertained using multi-frequency riometer data alone, but that the reconstruction requires a strong additional a priori assumption of the electron density profile, such as a parameterised model for the ionisation source. Nevertheless, the spectral index of the absorption could be used to determine if there is a significant component of hard precipitation that ionises the lower part of the D region, but it is not possible to infer the altitude distribution uniquely with this technique alone.

Derek McKay et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on gi-2021-25', Anonymous Referee #1, 15 Oct 2021
  • RC2: 'Comment on gi-2021-25', Shin-ichiro Oyama, 29 Oct 2021
  • AC1: 'Response to reviewers', Derek McKay, 29 Nov 2021

Derek McKay et al.

Derek McKay et al.

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Short summary
When radio waves from our Galaxy enter the Earth's atmosphere, they are absorbed by electrons in the upper atmosphere. It was thought that by measuring the amount of absorption, it would allow the height of these electrons in the atmosphere to be determined. If so, this would have significance for future instrument design. However, this paper demonstrates that it is not possible to do this, but it does explain how multiple-frequency measurements can nevertheless be useful.