This product contains Sea Level Anomaly (SLA) and geostrophic currents anomalies in the subpolar Southern Ocean, including its sea-ice covered parts, from 2013 to 2019. It has been constructed by combining observations from multiple satellites, including Cryosat-2, Sentinel-3A, and AltiKa. Along-track measurements have been processed with state-of-the-art algorithms, such as neural network waveform classification algorithm, or physical retracking for both leads and open ocean for AltiKa. Measurements are mapped daily on a 25-km grid south of 50°S.
Dataset processing and description is available in Auger et al., Southern Ocean Sea Level Anomaly in the Sea-Ice Covered Sector From Multimission Satellite Observations [submitted].
Keywords
Sea Level Anomaly, Southern Ocean, Geostrophic Currents, Altimetry, Sea Surface Height, Sea-Ice, Antarctica
Devices
We derive our product from high resolution along track measurements from Cryosat-2, AltiKa and Sentinel-3A. Cryosat and AltiKa are used for the full time series, Sentinel-3A data are included from 2016/06 to 2018/06.
Cryosat-2 is an ESA mission, which was launched in April 2010. Its SIRAL instrument is a Ku-band (i.e. frequency range from 13 to 17~GHz) radar altimeter working in three different modes: Low Resolution Mode (LRM) over most of the ocean, SARM (Synthetic Aperture Radar Mode) on the sea-ice, and SARInM (Synthetic Aperture Interferometric Mode) on the ice-sheets margins and temperate land-ice (Wingham et al. 2005). Only the ESA Cryosat-2 ICE SAR Baseline-C L1b dataset was used for this study. This dataset includes the sea-ice zones within Cryosat-2 SARM mask.
Sentinel-3A carries the dual-frequency Synthetic Aperture Radar Altimeter (SRAL) instrument, which was launched in 2016. Sentinel 3A CNES Processing Protocol (S3PP) data are used as they include the Zero-Padding and Hamming processings, which are necessary for SAR data in sea-ice zones \cite{quartly_retrieving_2019}.
SARAL/AltiKa is a CNES-ISRO (Centre National d'Etudes Spatiales, Indian Space Research Organisation) satellite, which was launched in February 2013. It carries a conventional (pulse limited) Ka-band (i.e. 35.75~GHz) radar altimeter.
