Abstract's details
Absolute Calibration and Validation of SWOT Nadir Altimetry Products over the Pertuis Charentais Using In-Situ Observations and Local Model
Event: 2025 SWOT Science Team Meeting
Session: Oceanography: Calibration and Validation
Presentation type: Poster
Satellite altimetry has revolutionized the observation of ocean dynamics and the monitoring of global mean sea level. However, in coastal zones, standard open-ocean processing techniques often fall short due to land contamination, complex bathymetry (limited knowledge of geoid), and dynamic coastal processes. In recent years, dedicated coastal altimetry products such as XTRACK (Birol et al., 2022) and ALTICAP (Birol et al., 2023) have significantly improved the retrieval of sea surface height (SSH) near the coast.
Despite these advances, retrieving precise sea level height from altimetry products in last kilometers of the coast remain challenging. This study focuses on the absolute calibration and validation (Cal/Val) of Geophysical Data Record (GDR) nadir altimetry products of SWOT mission over the Pertuis Charentais coastal region in Bay of Biscay - France, along track 419. SSH at 20 Hz is computed by refining key geophysical corrections, including wet tropospheric and ionospheric delays, dynamic atmospheric correction (DAC), sea state bias, and tidal effects.
Our validation framework integrates a comprehensive network of in-situ observations. GNSS (Global Navigation Satellite System) ground stations are used to improve the estimation of tropospheric and ionospheric delays. Tide gauges, pressure sensors, and the high-resolution local hydrodynamic model SCHISM (Semi-implicit Cross-scale Hydroscience Integrated System Model) are employed to enhance tidal and DAC corrections. These datasets enable the assessment and reduction of residual errors in altimetric measurements, particularly in the final kilometers before the coast.
Birol,F., Fuller N., Lyard,F., Cancet, M. Nino,F., Delebecque,C. Fleury,S. Toublanc,F. Melet,A. Saraceno,M. Léger,F. (2022) Coastal applications from nadir altimetry: Example of the X-TRACK regional products https://doi.org/10.1016/j.asr.2016.11.005
Birol, F., Bignalet-Cazalet, F., Cancet, M., Daguze, J.-A., Faugère, Y.,
Fkaier, W., Fouchet, E., Léger, F., Maraldi, C., Niño, F., Pujol, M.-I., and Thibaut, P.
(2023). Round Robin Assessment of altimetry algorithms for coastal sea surface height data.
Back to the list of abstractDespite these advances, retrieving precise sea level height from altimetry products in last kilometers of the coast remain challenging. This study focuses on the absolute calibration and validation (Cal/Val) of Geophysical Data Record (GDR) nadir altimetry products of SWOT mission over the Pertuis Charentais coastal region in Bay of Biscay - France, along track 419. SSH at 20 Hz is computed by refining key geophysical corrections, including wet tropospheric and ionospheric delays, dynamic atmospheric correction (DAC), sea state bias, and tidal effects.
Our validation framework integrates a comprehensive network of in-situ observations. GNSS (Global Navigation Satellite System) ground stations are used to improve the estimation of tropospheric and ionospheric delays. Tide gauges, pressure sensors, and the high-resolution local hydrodynamic model SCHISM (Semi-implicit Cross-scale Hydroscience Integrated System Model) are employed to enhance tidal and DAC corrections. These datasets enable the assessment and reduction of residual errors in altimetric measurements, particularly in the final kilometers before the coast.
Birol,F., Fuller N., Lyard,F., Cancet, M. Nino,F., Delebecque,C. Fleury,S. Toublanc,F. Melet,A. Saraceno,M. Léger,F. (2022) Coastal applications from nadir altimetry: Example of the X-TRACK regional products https://doi.org/10.1016/j.asr.2016.11.005
Birol, F., Bignalet-Cazalet, F., Cancet, M., Daguze, J.-A., Faugère, Y.,
Fkaier, W., Fouchet, E., Léger, F., Maraldi, C., Niño, F., Pujol, M.-I., and Thibaut, P.
(2023). Round Robin Assessment of altimetry algorithms for coastal sea surface height data.