# Copernicus Sentinel-3 marine altimetry Level-2
*data products*

## Specifications
- **level**: L2
- **distributor**: eumetsat
- **access endpoint**: https://sentiwiki.copernicus.eu/web/altimetry-products
- **access model**: open
- **primary data portal url**: https://sentiwiki.copernicus.eu/web/altimetry-products
- **use cases**: ["Sea surface height","Significant wave height","Altimeter wind speed"]
- **deployment context**: orbital
- **entity type**: data_product
- **last verified date**: 2026-06-11
- **verified by**: agency-doc
- **claim status**: agency-sourced
- **provider**: eumetsat
- **attributes**: {"level":"L2","distributor":"eumetsat","access_endpoint":"https://sentiwiki.copernicus.eu/web/altimetry-products","access_model":"open","primary_data_portal_url":"https://sentiwiki.copernicus.eu/web/altimetry-products","use_cases":"[\"Sea surface height\",\"Significant wave height\",\"Altimeter wind speed\"]","deployment_context":"orbital"}
- **relevance**: in-scope

## Editorial
Copernicus Sentinel-3 marine altimetry Level-2 (product ID SR_2_WAT) provides along-track sea-surface height, significant wave height, and altimeter wind speed from the SRAL dual-frequency SAR altimeter (Ku-band 13.575 GHz and C-band 5.41 GHz) carried on Sentinel-3A and Sentinel-3B.[^sentiwiki-altimetry-products][^s3-sral-marine-user-handbook] Sentinel-3A first data date is 2016-03-13; Sentinel-3B launched in April 2018. Along-track resolution is approximately 300 m at 20 Hz and approximately 7 km at 1 Hz; the product has no cross-track scanning capability. Geophysical corrections supplied in the file include dry and wet tropospheric, ionospheric, and sea-state bias corrections. Retracking uses SAMOSA+ for open-ocean waveforms, OCOG for coastal and ice surfaces, and MLE4 for pseudo-LRM mode; the precise distinction between SAMOSA+ and SAMOSA2 in the current processing baseline is not confirmed.[^s3-sral-marine-user-handbook][^user-eumetsat-s3-sral-baseline] Timeliness tiers are NRT (within 3 h of acquisition), STC (within 48 h), and NTC (within 1 month). The repeat cycle is 27 days. Products are in NetCDF inside Sentinel-SAFE packages, distributed open access under the Copernicus data licence via the Copernicus Data Space Ecosystem, processed by the EUMETSAT Marine Centre.[^user-eumetsat-s3-sral-baseline]

## Compositional position
- ocean-surface-winds (topics) --[topic_capabilities]--> Copernicus Sentinel-3 marine altimetry Level-2
- sea-state (topics) --[topic_capabilities]--> Copernicus Sentinel-3 marine altimetry Level-2

## Sources
- [sentiwiki-altimetry-products] | Sentinel-3 altimetry products, SentiWiki Copernicus | https://sentiwiki.copernicus.eu/web/altimetry-products | tier=agency-doc | accessed=2026-06-11
- [s3-sral-marine-user-handbook] | Sentinel-3 SRAL Marine User Handbook, ESA Earth Online | https://earth.esa.int/eogateway/documents/20142/1564943/Sentinel-3-SRAL-Marine-User-Handbook.pdf | tier=operator-engineering | accessed=2026-06-11
- [user-eumetsat-s3-sral-baseline] | Sentinel-3 SRAL altimetry processing baseline, EUMETSAT User Portal | https://user.eumetsat.int/resources/user-guides/sentinel-3-sral-altimetry-processing-baseline | tier=agency-doc | accessed=2026-06-11

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Source: https://eo-atlas.org/data_products/sentinel-3-altimetry-l2-marine
Maintainer: SpectraWorks B.V. (CC-BY 4.0)