The CNES CLS 2022 Mean Sea Surface: Short Wavelength Improvements from CryoSat-2 and SARAL/AltiKa High-Sampled Altimeter Data
Open Access
- 2 June 2023
- journal article
- research article
- Published by MDPI AG in Remote Sensing
- Vol. 15 (11), 2910
- https://doi.org/10.3390/rs15112910
Abstract
A new mean sea surface (MSS) was determined by focusing on the accuracy provided by exact-repeat altimetric missions (ERM) and the high spatial coverage of geodetic (or drifting) missions. The goal was to obtain a high-resolution MSS that would provide centimeter-level precision. Particular attention was paid to the homogeneity of the oceanic content of this MSS, and specific processing was also carried out, particularly on the data from the geodetic missions. For instance, CryoSat-2 and SARAL/AltiKa data sampled at high frequencies were enhanced using a dedicated filtering process and corrected from oceanic variability using the results of the objective analysis of sea-level anomalies provided by DUACS multi-missions gridded sea-level anomalies fields (MSLA). Particular attention was also paid to the Arctic area by combining traditional sea-surface height (SSH) with the sea levels estimated within fractures in the ice (leads). The MSS was determined using a local least-squares collocation technique, which provided an estimation of the calibrated error. Furthermore, our technique takes into account altimetric noises, ocean-variability-correlated noises, and along-track biases, which are determined independently for each observation. Moreover, variable cross-covariance models were fitted locally for a more precise determination of the shortest wavelengths, which were shorter than 30 km. The validations performed on this new MSS showed an improvement in the finest topographic structures, with amplitudes exceeding several cm, while also continuing to refine the correction of the oceanic variability. Overall, the analysis of the precision of this new CNES_CLS 2022 MSS revealed an improvement of 40% compared to the previous model, from 2015.Keywords
Funding Information
- French Space Agency
This publication has 15 references indexed in Scilit:
- On the resolutions of ocean altimetry mapsOcean Science, 2019
- Arctic Ocean Sea Level Record from the Complete Radar Altimetry Era: 1991–2018Remote Sensing, 2019
- Improving the quality of Sentinel-3A data with a hybrid mean sea surface model, and implications for Sentinel-3B and SWOTAdvances in Space Research, 2019
- Gauging the Improvement of Recent Mean Sea Surface Models: A New Approach for Identifying and Quantifying Their ErrorsJournal of Geophysical Research: Oceans, 2018
- An Assessment of State‐of‐the‐Art Mean Sea Surface and Geoid Models of the Arctic Ocean: Implications for Sea Ice Freeboard RetrievalJournal of Geophysical Research: Oceans, 2017
- Retracking of SARAL/AltiKa radar altimetry waveforms for optimal gravity field recoveryMarine Geodesy, 2016
- Slope correction for ocean radar altimetryJournal of Geodesy, 2014
- Retracking CryoSat-2, Envisat and Jason-1 radar altimetry waveforms for improved gravity field recoveryGeophysical Journal International, 2014
- The CNES_CLS11 Global Mean Sea Surface Computed from 16 Years of Satellite Altimeter DataMarine Geodesy, 2012
- A technique for objective analysis and design of oceanographic experiments applied to MODE-73Deep Sea Research and Oceanographic Abstracts, 1976