Abstract's details
SWOT-KaRIn Level-3 Algorithms and Products Overview
Event: 2025 SWOT Science Team Meeting
Session: Oceanography: Calibration and Validation
Presentation type: Oral
The DUACS system (Data Unification and Altimeter Combination System) produces, as part of the CNES/SALP project, Copernicus Marine Service and Copernicus Climate Change Service, high quality multi-mission altimetry Sea Level products for oceanographic applications, climate forecasting centers, geophysics and biology communities. These products consist in directly usable and easy to manipulate Level-3 (L3; along-track cross-calibrated SSHA) and Level-4 products (L4; multiple sensors merged as maps or time series).
Level-3 algorithms used for nadir altimeters have been extended to handle SWOT’s unique swath-altimeter data: upgrades with state-of-the-art Level-2 corrections and models from the research community, a data-driven and statistical approach to the removal of spurious and suspicious pixels, a multi-satellite calibration process that leverages the strengths of the pre-existing nadir altimeter constellation, a noise-mitigation algorithm based on a convolutional neural network. The L3 algorithms process the two resolutions of the L2 product: 2km and 250m. L3 products are freely available via the AVISO+ portal: the 2km product is produced and broadcast in near-real time.
Data reprocessings are carried out twice a year to improve data quality by enhancing Level-3 algorithms in line with the results of carried out studies and user feedback from the community. Major changes in version 2, published in January 2025, include a change of internal tides model, a quick fix of the SSB/SSHA offset in polar transitions, the recovery of eclipse gaps with good quality, an improvement of the coastline especially for estuaries areas and the addition of surface classification (ice/leads) in editing flag in Unsmoothed product. The major changes planned for version 3, to be released in September 2025, are a change of mean sea surface model (CNES/CLS 2025 MSS), an improvement of the neural network denoising, a change of the method used to derive currents and an addition of a technical product that will contain the various separate tidal components, an alternative solution for correcting internal tides, the various calibration components and experimental precipitation rates.
Level-3 algorithms used for nadir altimeters have been extended to handle SWOT’s unique swath-altimeter data: upgrades with state-of-the-art Level-2 corrections and models from the research community, a data-driven and statistical approach to the removal of spurious and suspicious pixels, a multi-satellite calibration process that leverages the strengths of the pre-existing nadir altimeter constellation, a noise-mitigation algorithm based on a convolutional neural network. The L3 algorithms process the two resolutions of the L2 product: 2km and 250m. L3 products are freely available via the AVISO+ portal: the 2km product is produced and broadcast in near-real time.
Data reprocessings are carried out twice a year to improve data quality by enhancing Level-3 algorithms in line with the results of carried out studies and user feedback from the community. Major changes in version 2, published in January 2025, include a change of internal tides model, a quick fix of the SSB/SSHA offset in polar transitions, the recovery of eclipse gaps with good quality, an improvement of the coastline especially for estuaries areas and the addition of surface classification (ice/leads) in editing flag in Unsmoothed product. The major changes planned for version 3, to be released in September 2025, are a change of mean sea surface model (CNES/CLS 2025 MSS), an improvement of the neural network denoising, a change of the method used to derive currents and an addition of a technical product that will contain the various separate tidal components, an alternative solution for correcting internal tides, the various calibration components and experimental precipitation rates.
Contribution: ST2025OS1-SWOT-KaRIn_Level-3_Algorithms_and_Products_Overview.pdf (pdf, 3249 ko)
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