15 Jun 2022
15 Jun 2022

Methods for Estimation of Ionospheric Layer Height Characteristics from Doppler Frequency and Time of Flight Measurements on HF Skywave Signals

Kristina Collins1, Steve Cerwin2, Philip Erickson3, Dev Joshi4, Nathaniel Frissell4, and Joe Huba5 Kristina Collins et al.
  • 1Case Western Reserve University, Glennan Bldg 9A, 10900 Euclid Avenue, Cleveland Ohio 44106, USA
  • 2HamSCI, c/o Dr. Frissell, USA
  • 3Haystack Observatory, Massachusetts Institute of Technology, 99 Millstone Road, Westford, MA 01886, USA
  • 4Department of Physics and Engineering, University of Scranton, Scranton, PA 18510-4642, USA
  • 5Syntek Technologies, Inc. 2751 Prosperity Ave. Suite 460, Fairfax, VA 22031, USA

Abstract. We demonstrate a methodology to estimate ionospheric virtual layer height characteristics using Doppler measurements from frequency locked time standard stations in conjunction with ionosonde measurements and ray-tracing models. We consider data from three events: the solar eclipse of 21 August 2017, a observations of the dawn terminator on 1 October 2019, and a time-of-flight study conducted 29 January 2020. Observations are consistent with a model in which mode splitting originates from different path length velocities associated with single and multiple hop modes as the virtual layer height changes. Support for this hypothesis comes from the complementary processes of 1) calculating Doppler shifts from virtual layer height changes and virtual layer height changes from Doppler shifts, and 2) the analysis of intermittent low-Doppler shift modes including correlation with ionosonde observations to help identify multihop propagation modes. We find that observations are in good agreement with measured data and simulations. We also find that the use of a precision frequency standard, such as a GPS-disciplined oscillator, at the receiving station is vital for ionospheric height measurements, since small errors in frequency estimation can lead to uncertainties on the order of tens of kilometers in resulting estimations of ionospheric height. The methods discussed herein provide a means to calculate path length estimates from distributed stations when integrated with other ionospheric measurements, helping to address the problem of under-sampling of the bottomside ionosphere.

Kristina Collins 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 egusphere-2022-327', Anonymous Referee #1, 08 Aug 2022
    • AC2: 'Reply on RC1', Kristina Collins, 13 Oct 2022
  • RC2: 'Comment on egusphere-2022-327', Stephen Kaeppler, 24 Aug 2022
    • AC1: 'Reply on RC2', Kristina Collins, 13 Oct 2022

Kristina Collins et al.

Kristina Collins et al.


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Short summary
Radio measurements of time standard stations can be used to measure changes in the ionosphere's height, but not the height itself. In this paper, we show that we can estimate ionospheric height using data from amateur radio stations along with other systems and simulations, that multiple signal paths can be found in this data, and that precisely controlling the receiver frequency is important for this approach to work. This work will help us analyze radio data collected by citizen scientists.