Product name: Sentinel-1 Freeze Thaw
Access to data and contact informaton:
Contact person: Juval Cohen (firstname.lastname(at)fmi.fi)
Data access via ftp:
Overview: The Sentinel-1 Freeze/Thaw (F/T) service provides daily morning and evening information on the F/T state of the soil in Finland. "Daily" and "6-day" products are generated. The daily product shows only observations from one day (morning or evening), while the 6-day mosaic product shows the median value of all observations over 6 days. A near real-time (NRT) product is generated up to 9 hours, and a standard product up to 37 hours after Sentinel-1 data acquisition. The NRT product uses the Sentinel-1 "NRT-3h" timeliness category data and includes ancillary information of 2m air temperature and snow depth. The standard product uses the Sentinel-1 "Fast-24h" timeliness category data and includes ancillary information of 2m air temperature, snow depth and soil's F/T state from the SMOS L3FT product. Data are provided as GeoTIFFs and as PNG quicklook files, in ETRS89 / UTM zone 35N projection and in 1 x 1 km spatial resolution. The product start date is September 1st 2020.
The F/T algorithm first finds the backscatter of the ground surface and the canopy, by applying a forest backscatter model on the SAR observations. The F/T state is then determined by comparing the retrieved backscatter values to empirically predefined frozen and thawed reference backscatter values. The output product has three categories for the soil state: frozen, uncertain, and thawed.
When using the data for commercial, educational or scientific works and publications, please cite the following publication:
Juval Cohen, Kimmo Rautiainen, Juha Lemmetyinen, Tuomo Smolander, Juho Vehviläinen and Jouni Pulliainen. 2021. Sentinel-1 based soil freeze/thaw estimation in boreal forest environments, Remote Sensing of Environment, Volume 254. DOI: 10.1016/j.rse.2020.112267