The Finnish Meteorological Institute (FMI) and international partners have published a data description paper on the Soil Moisture and Ocean Salinity (SMOS) Level-3 Soil Freeze–Thaw (FT) product, now available in its latest, fully reprocessed version. The paper, appearing in Earth System Science Data, details the dataset’s processing approach, validation, and updates, and highlights its importance for studies of the Earth’s cold-season land surface conditions.
The SMOS FT product, developed and operated by FMI under the European Space Agency (ESA), provides daily global information on soil freezing and thawing based on L-band passive microwave observations. The recently reprocessed version 3 introduces improved temporal filtering using Kalman-based noise reduction, updated reference conditions, and refined use of auxiliary data. Together, these updates enhance the product’s stability and consistency across the full SMOS mission record.
“Publishing this data description article strengthens transparency and usability of the product for researchers studying cold-season processes and carbon-cycle feedbacks,” says Kimmo Rautiainen, lead author and senior scientist at FMI.
The SMOS L3FT dataset is freely available through both the ESA SMOS online dissemination service (DOI 10.57780/sm1-fbf89e0) and the FMI dissemination server, supporting its continued use by the scientific community and operational users worldwide.
More information
Kimmo Rautiainen, Senior Scientist, Finnish Meteorological Institute, kimmo.rautiainen@fmi.fi
Rautiainen, K., Holmberg, M., Cohen, J., Mialon, A., Schwank, M., Lemmetyinen, J., de la Fuente, A., & Kerr, Y. (2025). An operational SMOS soil freeze–thaw product. Earth System Science Data, 17, 5337–5353. https://doi.org/10.5194/essd-17-5337-2025
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