In recent years, the European Space Agengy (ESA) has been conducting a range of activities to establish well defined and reliable Fiducial Reference Measurements (FRMs) for an increasing set of Earth Observation (EO) variables.

FRMs are defined as fully characterised and traceable ground measurements that follow community agreed guidelines outlined by the GEO/CEOS QA4EO framework. They provide a fiducial reference for users of satellite-based EO products who need validated products with reliable uncertainty estimations.


FRM activities typically comprise:

  1. Activities to identify or establish ground-based fiducial reference data for a particular variable
  2. Activities to specify the protocols and procedures to establish and verify such fiducial reference data
  3. Activities to validate relevant satellite products against established FRM data.


The FRM4SM project is aimed at FRM activities for soil moisture (SM) data and contains all three specified types of activities. It brings together the expert knowledge of insitu and satellite SM data providers and SM validation best practices integrated in an operational validation framework to establish new protocols for insitu data collection and their application for satellite SM quality control.





The International Soil Moisture Network (ISMN) hosts the largest publicly available collection of insitu soil moisture measurements. TU WIEN collects, quality controls and provides data from more than 70 individual networks through the ISMN.

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Quality Assurance for Soil Moisture (QA4SM) is a free online validation tool. Registered users can evaluate the performance of satellite soil moisture products, publish and share their results. AWST and TU Wien provide the interface, data access and processing resources for registered users to interactively perform validations.

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Soil Moisture and Ocean Salinity (SMOS) is ESA's satellite designed for the global observation of soil moisture over land. CESBIO develops and produces some of the most widely used soil moisture products derived from this sensor.

Available at