EGU2020-20898, updated on 10 Jan 2024
https://doi.org/10.5194/egusphere-egu2020-20898
EGU General Assembly 2020
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Comparison of high rate GNSS and GNSS-R measurements for detecting tidal bores in the Garonne River

Pierre Zeiger1, José Darrozes2, Frédéric Frappart1, Guillaume Ramillien2, Laurent Lestarquit3, Philippe Bonneton4, Natalie Bonneton4, and Valérie Ballu5
Pierre Zeiger et al.
  • 1Laboratoire d'Etudes en Géophysique et Océanographie Spatiales (LEGOS), UMR 5566, CNES/CNRS/UPS/IRD, OMP, 31400, Toulouse, France
  • 2Géosciences Environnement Toulouse (GET), UMR 5563, CNRS/UPS/IRD, OMP, 31400, Toulouse, France
  • 3Centre National d'Etudes Spatiales (CNES), 31401, Toulouse, France
  • 4Environnement et Paléo-environnements Océaniques et Continentaux (EPOC), UMR 5805, CNRS/Université de Bordeaux, Observatoire Aquitain des Sciences de l’Univers (OASU), 33615, Pessac, France
  • 5Littoral Environnements et Sociétés (LIENSs), UMR 7266, CNRS/Université de La Rochelle, 17000, La Rochelle, France

The Reflected Global Navigation Satellite System (GNSS-R) is a bi-static radar system in which the receiver collect GNSS signals reflected from the Earth surface and compares them with corresponding direct signals. Measurements can be performed on the waveforms to determine the elevation of the free surface, leading to applications such as ocean altimetry, inland water level variations, soil moisture, snow depth and atmospheric water changes. This study presents the potential of in-situ GNSS-R for tidal bore detection and characterization, and compares it to high rate GNSS observations and other reference datasets.

The data we used were acquired on 17th and 18th October 2016 in the Garonne River, at 126 km upstream the mouth of the Gironde estuary. We processed GNSS-based elevations from data acquired on a buoy at a 20 Hz sampling rate using differential GNSS (DGNSS) technique. Acoustic Doppler Current Profiler (ADCP) measurements as well as pressure data were used for validation purposes. These techniques show good results in estimating the amplitude of the first wave, the period of the tidal bore and the oceanic tides. All of these datasets were compared to the retrieval of GNSS-R signals above the river. We have processed the changes in water height throughout the acquisition using Larson et al. (2013) and Roussel et al. (2015) techniques. We finally separate the atmospheric component from the tidal bore and the oceanic tides ones.

 

Larson, K. M., Löfgren, J. S., and Haas, R. (2013). Coastal sea level measurements using a single geodetic gps receiver. Advances in Space Research, 51(8):1301–1310.

Roussel, N., Ramillien, G., Frappart, F. et al. (2015). Sea level monitoring and sea state estimate using a single geodetic receiver. Remote Sensing of Environment, 171:261 – 277.

How to cite: Zeiger, P., Darrozes, J., Frappart, F., Ramillien, G., Lestarquit, L., Bonneton, P., Bonneton, N., and Ballu, V.: Comparison of high rate GNSS and GNSS-R measurements for detecting tidal bores in the Garonne River, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20898, https://doi.org/10.5194/egusphere-egu2020-20898, 2020.