28 Mar 2022
28 Mar 2022

On the use of high frequency surface wave oceanographic research radars as bistatic single frequency oblique ionospheric sounders

Stephen R. Kaeppler1, Ethan S. Millera,b, Daniel Cole1,c, and Teresa Updyke2 Stephen R. Kaeppler et al.
  • 1Department of Physics and Astronomy, Clemson University, Clemson, South Carolina, USA
  • 2Old Dominion University, Virginia, USA
  • aformerly at: Johns Hopkins University Applied Physics Laboratory
  • bnow at: Systems and Technology Research, Beavercreek, Ohio, USA
  • cnow at: U.S. Space Force

Abstract. We demonstrate that bistatic reception of high frequency oceanographic radars can be used as single frequency oblique ionospheric sounders. We develop methods that are agnostic of the software defined radio system to estimate the group range from the bistatic observations. The group range observations are further used to estimate virtual height and equivalent vertical frequency at the midpoint of the oblique propagation path. Uncertainty estimates of the virtual height and equivalent vertical frequency are presented. We apply this analysis to observations collected from two experiments, run at two locations in different years, but utilizing similar software defined radio data collection systems. In the first experiment, 10 days of data were collected in March 2016 at a site located in Maryland, USA, while the second experiment collected 20 days of data in October 2020 at a site located in South Carolina, USA. In both experiments, three Coastal Oceanographic Dynamics and Applications Radars (CODARs) located along the North Carolina coast of the US were bistatically observed at 4.53718 MHz. The virtual height and equivalent virtual frequency were estimated in both experiments and compared with contemporaneous observations from a vertical incident Digisonde ionosonde at Wallops Island, VA, USA. We find good agreement in both experiments between the virtual height derived from the oblique CODAR observations versus the virtual height observed with the Digisonde at the same frequency. Variations in the virtual height from CODAR observations and the Digisonde are found to be nearly in phase with each other. We conclude from this investigation that observations that oceanographic radar can be used as single frequency oblique incidence sounders. We discuss applications with respect to investigations of traveling ionospheric disturbances, studies of day-to-day ionospheric variability, and using these observations in data assimilation.

Stephen R. Kaeppler 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-2022-39', Anonymous Referee #1, 11 Apr 2022
  • RC2: 'Comment on egusphere-2022-39', David Holdsworth, 18 Apr 2022

Stephen R. Kaeppler et al.

Data sets

Bistatic HF Observations of CODAR Radars from CARL and MSR sites Stephen R. Kaeppler

Stephen R. Kaeppler et al.


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Short summary
This investigation demonstrates how useful ionospheric parameters can be extracted from existing high frequency radars that are used for oceanographic research. The methodology presented can be used by radio amateurs and their results could be further used in ionospheric investigations.