The validation of ESA CCI SM is conducted by ETH Zurich who are independent from the production process. Results of the validation and intercomparison studies for each of the released versions of the product are described in detail in the corresponding Product Validation and Intercomparison Report (PVIR).
The Quality Assurance for Soil Moisture project (QA4SM) provides an operational online validation service for soil moisture products. It can be used to validate the ESA CCI SM product for spatial and temporal subsets defined by the user. An example validation for ESA CCI SM v07.1 against ERA-5 for the period 2007-2020 is shown below: