Abstract's details
Measuring longitudinal river profiles from Sentinel-6 Fully-Focused SAR mode
CoAuthors
Event: 2023 Ocean Surface Topography Science Team Meeting
Session: Science IV: Altimetry for Cryosphere and Hydrology
Presentation type: Type Oral
Contribution: PDF file
Abstract:
While satellite radar altimetry missions have been used uniquely when rivers are observed at nadir, here we developed a new processing technique that exploits off-nadir signals to retrieve the longitudinal river profiles (in certain conditions).
This breakthrough in rivers observation using radar altimeters is possible with the emergence of the Fully Focused SAR processing (Egido et al, 2017, Fully Focused SAR Altimetry: Theory and Applications) that provides 50cm along track resolution measurements. FFSAR is particularly accurate on Sentinel-6 MF mission which embarks the first altimeter (POSEIDON-4) with an open-burst SAR mode.
We designed a new algorithm that exploits off-nadir echoes, combined with a river centerline to estimate the water surface elevation accounting for the slant range effect. The longitudinal river profile is obtained with a 10m posting rate and a vertical precision of the order of 10cm RMS.
In this study, we particularly focused in Marmande/FRANCE location where Sentinel-6 MF satellite flies along the Garonne River over a transect of 20km. Processing data over 12 months, we will show how the Garonne River longitudinal profile evolves between low and high waters. In parallel, validation campaign has been held to provide reference measurements using UAVs equipped with laser altimeters (Vortex company). Validation shows a good agreement between UAV and Sentinel-6 longitudinal profile.
This new technique, even limited to few cases when Sentinel-6 fly along rivers, opens new perspective in the observations and understanding of longitudinal river profile evolution in time and space.
This breakthrough in rivers observation using radar altimeters is possible with the emergence of the Fully Focused SAR processing (Egido et al, 2017, Fully Focused SAR Altimetry: Theory and Applications) that provides 50cm along track resolution measurements. FFSAR is particularly accurate on Sentinel-6 MF mission which embarks the first altimeter (POSEIDON-4) with an open-burst SAR mode.
We designed a new algorithm that exploits off-nadir echoes, combined with a river centerline to estimate the water surface elevation accounting for the slant range effect. The longitudinal river profile is obtained with a 10m posting rate and a vertical precision of the order of 10cm RMS.
In this study, we particularly focused in Marmande/FRANCE location where Sentinel-6 MF satellite flies along the Garonne River over a transect of 20km. Processing data over 12 months, we will show how the Garonne River longitudinal profile evolves between low and high waters. In parallel, validation campaign has been held to provide reference measurements using UAVs equipped with laser altimeters (Vortex company). Validation shows a good agreement between UAV and Sentinel-6 longitudinal profile.
This new technique, even limited to few cases when Sentinel-6 fly along rivers, opens new perspective in the observations and understanding of longitudinal river profile evolution in time and space.