Level-3 5Hz altimeter product

The DUACS along-track (level 3) experimental product is deduced from full rate (20 to 40Hz) Level-2 altimeter measurements and delivered with a 5Hz (about 1.3km) sampling. The sea surface height measurement from Sentinel-3A, Jason-2, Jason-3, SARAL/AltiKa and Cryosat-2 have been processed over the [mid-2016, 2018] period. The product cover the North Atlantic Ocean and European Seas. Different essential geophysical variables are disseminated. They correspond to the sea level anomaly, different geophysical corrections applied (i.e. dynamic atmospheric correction, ocean tide, internal tide, long-wavelength error correction), auxiliary products used in the processing (i.e. MDT) and derivate across-track geostrophic current. The DUACS processing includes valid data selection, multimission cross-calibration and residual noise filtering. Up-to-date geophysical corrections and different innovative processing, for both SAR and LRM measurements, have been used in order to reduce the sea surface height errors at short wavelengths. They include adaptative (Thibaukt et al., 2017; Poisson et al., 2018) and LR-RMC (Low Resolution with Range Migration Correction) (Boy et al., 2017; Moreau et al., 2021) processing techniques and Jason and Sentinel-3 respectively, and High Frequency Adjustment (HFA) combined with a 2D Sea State Bias (SSB) correction on LRM measurement (Tran et al., 2019)