Product Description


SWI index for Eastern Europe for
the month of July 1999.

Global, coarse-resolution soil moisture data (25-50 km) are derived from backscatter measurements acquired with scatterometers onboard the satellites ERS-1 and ERS-2 (1991 to present) and the three MetOp satellites (2006-2020). Two different product types are derived:

  • Level 2 products representing the soil moisture content within a thin soil surface layer (< 2 cm) during the time of overflight of the satellite.
  • Level 3 products representing the water content in the soil profile, regularly sampled in space and time.

The Level 2 surface soil moisture (SSM) data are derived using a change detection method that relies upon the multi-incidence observation capabilities of the ERS and METOP scatterometers to model the effects of vegetation phenology. The surface soil moisture values are scaled between 0 and 1, representing zero soil moisture and saturation respectively. Retrieval is not possible over tropical forest which affects about 6.5% of the land surface area.

Level 3 soil moisture products are obtained by some kind of modelling approach using the ASCAT Level 2 and other data sources as input. A typical Level 3 product is an estimate of the soil moisture content for different soil layers and different temporal and spatial sampling characteristics, tailored to the needs of specific user groups. Our standard Level 3 product is the so-called Soil Water Index (SWI) that is a measure of the profile soil moisture content obtained by filtering the surface soil moisture time series with an exponential function.

Note: Metop-ASCAT data are available via EUMETSAT. See the links:

For access to level 2 and level 3 soil moisture products derived as timeseries on a discrete global grid please contact radar@ipf.tuwien.ac.at.