TOWARDS PHYSICALLY CONSISTENT COPERNICUS IMAGING MICROWAVE RADIOMETER LEVEL 2 PRODUCTS FOR THE GLOBAL OCEAN AND ATMOSPHERE
Marzo 25, 2026RECENT PROGRESS IN SMALLSAT CONSTELLATIONS, BEAM-STEERING ARRAYS, AND COGNITIVE SENSING FOR MICROWAVE IMAGING AND SOUNDING OF THE ATMOSPHERE
Marzo 25, 2026J. Boutin1, F. Bonjean2, X. Perrot3, H. Bellenger3, J. Vergely4, A. Parracho2, F. Rouffi4, S. Guimbard5, J. Jouanno6, N. Reul7, R. Catany8, G. Corato9, N. Kolodziejcyk7, L. Bertino10, M. Martin11, R. Raj10, G. Reverdin2, R. Sabia12
1LMD/IPSL, 2LOCEAN/CNRS, 3LMD/CNRS, 4ACRI-st, 5OCEANSCOPE, 6LEGOS, 7LOPS, 8ALBAVALOR, 9ADWAISEO, 10NERSC, 11METOFFICE, 12ESA
Sea Surface Salinity (SSS) is an Essential Ocean and Climate Variable, increasingly relied upon for ocean and climate monitoring. The Soil Moisture Ocean Salinity (SMOS), Aquarius, and Soil Moisture Active-Passive (SMAP) satellite missions provide SSS measurements with very different instrumental characteristics, resulting in specific measurement properties. The ESA-funded Climate Change Initiative Salinity project (CCI+SSS) aims to produce a consistent Climate Data Record (CDR) based on these satellite observations. The instrumental differences are carefully adjusted to generate a homogeneous CDR [Boutin et al., 2021]. An optimal interpolation in the time domain, without temporal relaxation or spatial smoothing, preserves original data variability. CCI+SSS fields effectively monitor weekly to interannual signals at 50 km to basin scales.
In this presentation, we will review the algorithms and performances of the most recent CCI SSS products.
The CCI+SSS version 5.5 dataset (Boutin et al. 2025) covers the 2010-2023 period. Following user recommendations, weekly and monthly SSS fields are provided globally on a 0.25° regular grid and, in polar regions, on EASE 25km polar grids. The global precision against reference gridded data is 0.14 pss, and the uncertainties provided in the CCI product are in good agreement with observations (within 30%). Compared to version 4, systematic underestimation in 2010, overestimation from April to August 2015 at high latitudes, and Radio Frequency Interferences (RFI) contamination (Bonjean et al. 2024) have been significantly reduced.
CCI+SSS version 6 will be released in early 2026 and will extend the data record to 2010-2024. It will include a correction for the diurnal sea surface temperature variations in the top centimetre of the ocean, which significantly improves SSS retrievals over evening orbits under low wind conditions. It will also include a correction for solar contamination, which notably enhances the interannual SSS variability in the Northern Hemisphere. Lastly, it will include updates to the brightness temperature-wind model and the RFI contamination correction.
Through selected examples, we will demonstrate how these products allow us to monitor SSS variability over the past 15 years, supporting a better understanding of ocean processes and data assimilation.
References
Bonjean, et al. (2024), “Recovery of SMOS Salinity Variability in RFI-Contaminated Regions,” in IEEE Transactions on Geoscience and Remote Sensing, doi: 10.1109/TGRS.2024.3408049.
Boutin, J., et al. (2021), Satellite-Based Sea Surface Salinity Designed for Ocean and Climate Studies, Journal of Geophysical Research: Oceans, 126(11), e2021JC017676, doi: https://doi.org/10.1029/2021JC017676.
Boutin, J., et al., “ESA Sea Surface Salinity Climate Change Initiative (Sea_Surface_Salinity_cci): Weekly and monthly sea surface salinity products from L-band, v5.5.” NERC EDS Centre for Environmental Data Analysis, 2025. doi: 10.5285/7294D93479654C139770F13FAE4142D1.
