The Level-2 Ka-band Radar Interferometer (KaRIn) low rate (LR, ocean) sea surface height (SSH) data product from the Surface Water and Ocean Topography (SWOT) mission, also referenced by the short name L2_LR_SSH, provides ocean topography measurements from the low rate ocean data stream of the KaRIn instrument, spanning 60 km on either side of the nadir altimeter with a nadir gap. The L2_LR_SSH product is available continuously and globally, although different versions of the product may be produced at different latencies and/or through different reprocessing with refined input data. Note that L2_LR_SSH does not include SSH data from the SWOT nadir altimeter. SWOT launched on December 16, 2022 into a 1-day repeat orbit for the "calibration" or "fast-sampling" phase of the mission, which completed in early July 2023. After the calibration phase, SWOT entered a 21-day repeat orbit in August 2023 to start the "science" phase of the mission. The SWOT L2_LR_SSH product is organized in four files : ['Basic'], ['WindWave'], ['Expert'] and ['Unsmoothed'], each identified by its own DOI and described on a metadata sheet via the links below. - The ['Basic'] file is intended for users who are interested in SSH measurements and who will use the KaRIn measurements as provided. - The ['WindWave'] file is intended for users interested in wind and wave information. The ['Unsmoothed'] file, also intended for expert users, is provided on a finer 'native' grid of 250-m (with minimal smoothing applied), and has a significantly larger data volume than the other files. - The ['Expert'] file is intended for expert users who are interested in the details of how the KaRIn measurements were derived and who may use detailed information for their own custom processing. - The ['Unsmoothed'] file, also intended for expert users, is provided on a finer 'native' grid of 250-m (with minimal smoothing applied), and has a significantly larger data volume than the other files. Variables included: - Basic L2_LR_SSH includes corrected sea surface height (SSH), sea surface height anomaly (SSHA), data quality flags, geophysical reference fields, and height correction information on a 2 km geographically fixed grid. - WindWave L2_LR_SSH includes measured significant wave height (SWH), normalized radar cross section (NRCS or backscatter cross section or sigma0), wind speed derived from sigma0 and SWH, wind and wave model information, and quality flags on a 2 km geographically fixed grid. - Expert L2_LR_SSH, which includes copies of all variables in the Basic and WindWave files, plus more detailed information on the KaRIn instrument and environmental corrections, radiometer data, and geophysical models on a 2 km geographically fixed grid. - Unsmoothed L2_LR_SSH, which includes sea surface height (SSH) and sigma0 without additional smoothing relative to the native KaRIn downlink resolution on a ~250 m native (center-beam) grid. The Unsmoothed file contains two groups, left and right, each of which contains the data for half (one side from nadir) of the KaRIn swath. August 2024: V2.0 L2_LR_SSH version 2.0 (version C) products declared as validated by the SWOT project. March 2024: V2.0 Production and distribution of the pre-validated L2_LR_SSH version 2.0 (or version C) products: - PIC0 for forward-processed version C products: November 23, 2023 to present, - PGC0 for reprocessed version C products: - March 30 to July 10, 2023 (phase CalVal) and from July 26,2023 to January 25, 2024 (phase Science) November 2023: V1.0 The beta pre-validated L2_LR_SSH version 1.0 product (summer 2023 reprocessing release) is available only for the 1-day CalVal orbit phase, from March 29 to July 10, 2023, and the 21-day Science orbit phase from September 7 to November 21, 2023.

The Level-2 Ka-band Radar Interferometer (KaRIn) low rate (LR, ocean) sea surface height (SSH) data product from the Surface Water and Ocean Topography (SWOT) mission, also referenced by the short name L2_LR_SSH, provides ocean topography measurements from the low rate ocean data stream of the KaRIn instrument, spanning 60 km on either side of the nadir altimeter with a nadir gap. The L2_LR_SSH product is available continuously and globally, although different versions of the product may be produced at different latencies and/or through different reprocessing with refined input data. Note that L2_LR_SSH does not include SSH data from the SWOT nadir altimeter. The SWOT L2_LR_SSH product is organized in four files, the L2_LR_SSH ['Unsmoothed'] is described in this metadata sheet. The 3 other file types (['Basic'], ['WindWave'], ['Expert']) are described by 3 different metadata sheets that can be accessed via the links below. The ['Unsmoothed'] file, also intended for expert users, is provided on a finer 'native' grid of 250-m (with minimal smoothing applied), and has a significantly larger data volume than the other files. The ['Basic'] file is intended for users who are interested in SSH measurements and who will use the KaRIn measurements as provided. The ['WindWave'] file is intended for users interested in wind and wave information. The ['Expert'] file is intended for expert users who are interested in the details of how the KaRIn measurements were derived and who may use detailed information for their own custom processing. The ['Unsmoothed'] L2_LR_SSH includes sea surface height (SSH) and sigma0 without additional smoothing relative to the native KaRIn downlink resolution on a ~250 m native (center-beam) grid. The Unsmoothed file contains two groups, left and right, each of which contains the data for half (one side from nadir) of the KaRIn swath. May 2025: v3.0 (version D) Production and distribution of the L2_LR_SSH version D products: - PID0 for forward-processed version D products: from May 6, 2025 onward, - PGD0 for reprocessed version D products: from March 30 to July 10, 2023 (phase CalVal) and from July 26, 2023 to May 19, 2025 (phase Science) is ongoing. August 2024: v2.0 (version D) L2_LR_SSH version C products declared as validated by the SWOT project. March 2024: v2.0 (version C) Production and distribution of the pre-validated L2_LR_SSH version C products: - PIC0 for forward-processed version C products: November 23, 2023 to present, - PGC0 for reprocessed version C products: from March 30 to July 10, 2023 (phase CalVal) and from July 26, 2023 to January 25, 2024 (phase Science) November 2023: v1.0 The beta pre-validated L2_LR_SSH version 1.0 product (summer 2023 reprocessing release) is available only for the 1-day CalVal orbit phase, from March 29 to July 10, 2023, and the 21-day Science orbit phase from September 7 to November 21, 2023.

The Level-2 Ka-band Radar Interferometer (KaRIn) low rate (LR, ocean) sea surface height (SSH) data product from the Surface Water and Ocean Topography (SWOT) mission, also referenced by the short name L2_LR_SSH, provides ocean topography measurements from the low rate ocean data stream of the KaRIn instrument, spanning 60 km on either side of the nadir altimeter with a nadir gap. The L2_LR_SSH product is available continuously and globally, although different versions of the product may be produced at different latencies and/or through different reprocessing with refined input data. Note that L2_LR_SSH does not include SSH data from the SWOT nadir altimeter. The SWOT L2_LR_SSH product is organized as a collection of four subproducts, the L2_LR_SSH ['Basic'] is described in this metadata sheet. The 3 other file types (['WindWave'], ['Expert'], ['Unsmoothed']) are described by 3 different metadata sheets that can be accessed through the links below. The ['Basic'] file on this metadata sheet, is intended for users who are interested in SSH measurements and who will use the KaRIn measurements as provided. The ['Basic'] L2_LR_SSH includes corrected sea surface height (SSH), sea surface height anomaly (SSHA), data quality flags, geophysical reference fields, and height correction information on a 2-km geographically fixed grid. The ['WindWave'] L2_LR_SSH is intended for users interested in wind and wave information. The ['Expert'] L2_LR_SSH is intended for expert users who are interested in the details of how the KaRIn measurements were derived and who may use detailed information for their own custom processing. The ['Unsmoothed'] L2_LR_SSH, also intended for expert users, is provided on a finer 'native' grid of 250-m (with minimal smoothing applied), and has a significantly larger data volume than the other files. May 2025: v3.0 (version D) Production and distribution of the L2_LR_SSH version D products: - PID0 for forward-processed version D products: from May 6, 2025 onward, - PGD0 for reprocessed version D products: from March 30 to July 10, 2023 (phase CalVal) and from July 26, 2023 to May 19, 2025 (phase Science) is ongoing. August 2024: v2.0 (version D) L2_LR_SSH version C products declared as validated by the SWOT project. March 2024: v2.0 (version C) Production and distribution of the pre-validated L2_LR_SSH version C products: - PIC0 for forward-processed version C products: November 23, 2023 to present, - PGC0 for reprocessed version C products: from March 30 to July 10, 2023 (phase CalVal) and from July 26, 2023 to January 25, 2024 (phase Science) November 2023: v1.0 The beta pre-validated L2_LR_SSH version 1.0 product (summer 2023 reprocessing release) is available only for the 1-day CalVal orbit phase, from March 29 to July 10, 2023, and the 21-day Science orbit phase from September 7 to November 21, 2023.

The SWOT L3_LR_SSH product provides ocean topography measurements obtained from the SWOT KaRIn and nadir altimeter instruments, merged into a single variable. The dataset includes measurements from KaRIn swaths on both sides of the image, while the measurements from the nadir altimeter are located in the central columns. In the areas between the nadir track and the two KaRIn swaths, as well as on the outer edges of each swath (restricted to cross-track distances ranging from 10 to 60 km), default values are expected. SWOT L3_LR_SSH is a cross-calibrated product from multiple missions that contains only the ocean topography content necessary for thematic research (e.g., oceanography, geodesy) and related applications. This product is designed to be simple and ready-to-use, and can be combined with other altimetry missions. The SWOT L3_LR_SSH product is a research-orientated extension of the L2_LR_SSH product, distributed by the SWOT project (NASA/JPL and CNES). SWOT L3_LR_SSH is managed by the SWOT Science Team project DESMOS. The "Expert" version of SWOT L3_LR_SSH (the "Basic" version is the subject of a separate metadata sheet) includes each algorithm, correction, or external model incorporated into the SWOT L3_LR_SSH product as a separate layer. In addition to the SSH anomalies, this "Expert" version also includes mean dynamic topography (as in the "Basic" version), backscatter coefficient (sigma0), mean sea surface and geostrophic currents (absolute and anomalies).

This Level 2 product provides marine reflectances from the VENµS mission, processed with the Polymer algorithm, on a subset of sites with coastal or inland areas. VENµS (Vegetation and Environment monitoring on a New Micro-Satellite) is a Franco-Israeli satellite launched in 2017, dedicated to the fine and regular monitoring of terrestrial vegetation, in particular cultivated areas, forests, protected natural areas, etc. The images acquired in 12 spectral bands by a camera provided by CNES, on a selection of about one hundred scientific sites spread over the planet, are of high spatial (5 m) and temporal resolution. The lifetime of the VENµS satellite has been divided into two phases: a first phase VM1 at an altitude of 720 km with a 2-day revisit, a native spatial resolution of 5.3 m and a swath of 27.6 km from August 2017 to November 2020, and a second phase VM5 at an altitude of 560 km with a daily revisit, a native spatial resolution of 4.1 m and a swath of 21.3 km from March 2022 to July 2024. VENµS is the first sensor on board an orbiting satellite to combine such revisit frequency and spatial finesse for vegetation monitoring. A subset of sites with coastal areas or inland waters have been identified to generate Level 2 data dedicated to marine reflectance. The geographical areas covered are given through a kmz file, see below to download it. This Level 2 data product has been processed using the Polymer algorithm developed by Hygeos (https://hygeos.com/en/polymer/) and provides marine reflectances for the VENµS bands from 420 to 865 nm. These reflectances, without units, include a bidirectional normalization for the Sun at nadir and the observer at nadir. VENµS data products (Level-1, Level-2 and Level-3) are primarily generated with the MAJA algorithm, further information can be found on THEIA website: https://www.theia-land.fr/en/product/venus/ References - Dick, A., Raynaud, J.-L., Rolland, A., Pelou, S., Coustance, S., Dedieu, G., Hagolle, O., Burochin, J.-P., Binet, R., Moreau, A., 2022. VENμS: Mission Characteristics, Final Evaluation of the First Phase and Data Production. Remote Sensing 14, 3281. https://doi.org/10.3390/rs14143281 - Steinmetz, F., Deschamps, P.-Y., Ramon, D., 2011. Atmospheric correction in presence of sun glint: application to MERIS. Optics Express 19, 9783–9800. https://doi.org/10.1364/OE.19.009783 - Steinmetz, F., Ramon, D., 2018. Sentinel-2 MSI and Sentinel-3 OLCI consistent ocean colour products using POLYMER, in: SPIE Asia-Pacific Remote Sensing Proceedings. https://doi.org/10.1117/12.2500232 - Cox, C., Munk, W., 1954. Measurement of the Roughness of the Sea Surface from Photographs of the Sun’s Glitter. J. Opt. Soc. Am. 44, 838. https://doi.org/10.1364/JOSA.44.000838