Preprints
https://doi.org/10.5194/esurf-2020-108
https://doi.org/10.5194/esurf-2020-108

  28 Jan 2021

28 Jan 2021

Review status: this preprint is currently under review for the journal ESurf.

Precise water level measurements using low-cost GNSS antenna arrays

David J. Purnell1, Natalya Gomez1, William Minarik1, David Porter2, and Gregory Langston1 David J. Purnell et al.
  • 1Department of Earth and Planetary Sciences, McGill University, 3450 University Street, Montreal, Quebec, Canada, H3A0E8
  • 2Lamont-Doherty Earth Observatory, Columbia University, New York, NY, USA

Abstract. We have developed a ground-based Global Navigation Satellite System Reflectometry (GNSS-R) technique for monitoring water levels with a comparable precision to standard tide gauges (e.g., pressure transducers) but at a fraction of the cost and using commercial products that are straightforward to assemble. As opposed to using geodetic-standard antennas that have been used in previous GNSS-R literature, we use multiple co-located low-cost antennas to retrieve water levels via inverse modelling of Signal-to-Noise ratio data. The low-cost antennas are advantageous over geodetic-standard antennas because they are much less expensive (even when using multiple antennas in the same location) and they can be used for GNSS-R analysis over a greater range of satellite elevation angles. We validate our technique using arrays of four antennas at three test sites with variable tidal forcing and co-located operational tide gauges. The root mean square error between the GNSS-R and tide gauge measurements ranges from 0.7–1.2 cm when using all four antennas at each site. We find that using four antennas instead of a single antenna improves the precision by 30–50 % and preliminary analysis suggests that four appears to be the optimum number of co-located antennas. In order to obtain precise measurements, we find that it is important for the antennas to track GPS, GLONASS and Galileo satellites over a wide range of azimuth angles (at least 140 degrees) and elevation angles (at least 30 degrees).

David J. Purnell 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 esurf-2020-108', Anonymous Referee #1, 02 Mar 2021
    • AC1: 'Reply on RC1', David Purnell, 27 Mar 2021
  • RC2: 'Comment on esurf-2020-108', Manuella Fagundes, 10 Mar 2021
    • AC2: 'Reply on RC2', David Purnell, 27 Mar 2021

David J. Purnell et al.

David J. Purnell et al.

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Short summary
In this study we present a new technique for precisely monitoring water levels (e.g., for monitoring sea level, rivers or lakes) using low-cost equipment that is simple to build and install. The technique builds on previous work using antennas that were designed for positioning and navigation purposes. However, we use multiple antennas in the same location to obtain more precise measurements. Our technique is validated by comparing with purpose-built water level sensors at three test sites.