This is the Sea Ice Thematic Data Product (TDP) V1 resulting from the _$$ESA FDR4ALT project$$ https://www.fdr4alt.org/ and containing the sea ice related geophysical parameters, along with associated uncertainties: snow depth, radar and sea-ice freeboard, sea ice thickness and concentration.
The collection covers data for the ERS-1, ERS-2 and Envisat missions, and bases on Level 1 data coming from previous reprocessing (ERS REAPER and the Envisat V3.0) but taking into account the improvements made at Level 0/Level 1 in the frame of FDR4ALT (_$$ALT FDR$$ https://earth.esa.int/eogateway/catalog/fdr-for-altimetry).
The Sea Ice TDP provides data from the northern or southern hemisphere in two files corresponding to the Arctic and Antarctic regions respectively for the winter periods only, i.e., October to June for the Arctic, and May to November for the Antarctic.
For many aspects, the Sea Ice TDP is very innovative:
First time series of sea-ice thickness estimates for ERS
Homogeneous calibration, allowing the first Arctic radar freeboard time series from ERS-1 (1991) to CryoSat-2 (2021)
Uncertainties estimated along-track with a bottom-up approach based on dominant sources
ERS pulse blurring error corrected using literature procedure [Peacock, 2004]
The FDR4ALT products are available in NetCDF format. Free standard tools for reading NetCDF data can be used.
Information for expert altimetry users is also available in a dedicated NetCDF group within the products.
Please consult the _$$FDR4ALT Product User Guide$$ https://earth.esa.int/eogateway/documents/d/earth-online/fdr4alt-products-user-guide before using the data.
The FDR4ALT datasets represent the new reference data for the ERS/Envisat altimetry missions, superseding any previous mission data. Users are strongly encouraged to make use of these datasets for optimal results.