FRM Data Hub for Sentinel-3 Land Altimetry
1. Overview
The FRM Data Hub for Sentinel-3 Land Altimetry provides access to Fiducial Reference Measurements (FRM) collected as part of the St3TART-FO (Sentinel-3 Topography mission Assessment through Reference Techniques Follow-On) project. FRM are independent, tailored and fully characterised reference measurements with traceable uncertainty characterisation, that shall provide the users full confidence in the observations through validation of the satellite observations. The FRM measurements elaborated within St3TART-FO support the validation of the Copernicus Sentinel-3 SAR altimeter for Hydro-Cryo Thematic Data Products across three surface types:
- Inland Waters
- Sea Ice
- Land Ice
Additionally, they pave the way for future altimetry missions such as CRISTAL and S3 Next-Generation Topography, while also enabling potential synergies with the Copernicus CIMR expansion mission.
The St3TART-FO project is conducted by a consortium led by NOVELTIS (Contract No. 4000144565/24/I-KE) within the framework of the European Union’s Copernicus programme, implemented by the European Space Agency.
2. How to Access the Data
The FRM Data Hub for Sentinel-3 Hydro-Cryo Altimetry is hosted by NOVELTIS and accessible via the following link:
https://frm-datahub.noveltis.fr/
Data can be downloaded:
- Directly via the interface of the FRM Data Hub
- Through an API (access details provided on the FRM Data Hub)
The datasets are provided as ZIP files containing one or more NetCDF files, with each dataset version uniquely identified.
For registration and detailed usage instructions, please refer to the FRM Data Hub User Guide.
3. Collection Description
The St3TART-FO FRM collection consists of datasets from two types of sites:
Super Sites
- Serve as FRM quality reference sites within the project.
- Fully instrumented with permanent sensors and actively maintained by the St3TART-FO project to ensure data consistency.
- Currently available for Inland Waters only.
Opportunity Sites
- Collected data from public national networks and/or from existing campaigns.
- Contribute valuable measurements but may not always guarantee FRM compliance (g., due to potential maintenance limitations within national networks).
- Information on thematic surfaces:
- Inland Waters: complement super sites using existing networks.
- Sea Ice: data from a network of campaign-based opportunity sites.
- Land Ice: includes fixed stations and dedicated field campaigns.
For full details on these sites and their available data products, please visit the FRM Data Product Description page. It includes product overviews, data levels and structures, processing methods, validation and dissemination.
4. Spatial and Temporal Coverage
- Spatial coverage: 90°N to 90°S, 180°W to 180°E
- Temporal coverage: 2016-10-01 – Present
5. Availability
Worldwide access.
6. Data Citation Guidelines
Users, who, in their activity, use ESA Earth Observation data that have been assigned a DOI, are asked to use it when citing the data source in their publications: European Space Agency, 2025, FRM Data Hub for Sentinel-3 Land Altimetry database.
The DOI URL is: https://doi.org/10.57780/s3d-861209e
7. Resources
FRM Provision Roadmap for Inland Waters
FRM Provision Roadmap for Sea Ice
FRM Provision Roadmap for Land Ice
FRM Protocols and Procedures for Inland Waters
FRM Protocols and Procedures for Sea Ice
FRM Protocols and Procedures for Land Ice
8. References
Goryl, P.; Fox, N.; Donlon, C.; Castracane, P. Fiducial Reference Measurements (FRMs): What Are They? Remote Sens. 2023, 15, 5017. https://doi.org/10.3390/rs15205017