EGU23-16006, updated on 26 Feb 2023
EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Analyzing the reliability of in situ soil moisture measurements for satellite product validation: What makes fiducial reference measurements fiducial?

Irene Himmelbauer1, Alexander Gruber1, Daniel Aberer1, Wolfgang Preimesberger1, Pietro Stradiotti1, Wouter A. Dorigo1, Alexander Boresch2, Monika Tercjak2, Francois Gibon3, Arnaud Mialon3, Philippe Richaume3, Yann Kerr3, Raul Diez Garcia4, Raffaele Crapolicchio4, Roberto Sabia4, Klaus Scipal4, and Philippe Goryl4
Irene Himmelbauer et al.
  • 1TU Wien, Climate and Environmental Remote Sensing, Geodesy and Geoinformation, Vienna, Austria (
  • 2Applied Science Softaware and Technology (AWST), Vienna, Austria
  • 3CESBIO, Université de Toulouse, CNES/CNRS/INRAe/IRD/UPS, Toulouse, France
  • 4European Space Agency (ESA) - ESRIN, Frascati, Italy

To this day, in situ soil moisture data is viewed as ground truth by the satellite soil moisture (SSM) community. In general, little is still commonly known regarding the traceability of ground measurement uncertainty and their overall in uncertainty budget, which can impact satellite SSM product quality assessments.

Within ESA’s “Fiducial Reference Measurement for Soil Moisture (FRM4SM, May 2021 - May 2023)” project, objectives are set towards building fully characterized and traceable (i.e., fiducial) in situ measurements following community-agreed guidelines from the GEOS/CEOS Quality Assurance for Soil Moisture (QA4EO) framework. These so called “fiducial reference data” (FRM) should have associated Quality Indicators (QI) attached to evaluate their fitness for purpose building upon agreed reference standards (SI if possible). Moreover, such data should be easily and openly accessible, validation case studies should demonstrate their utility and reliability, and protocols and procedures should be established for the usage of such FRM datasets to make scientific studies intercomparable and reproducible.

As part of the FRM4SM project, the following questions were addressed using the International Soil Moisture Network (ISMN) as a ground reference database and the Soil Moisture and Ocean Salinity (SMOS) mission as an example satellite product:

(1) What makes “fiducial reference data” fiducial?

(2) Is the creation of a globally-representative FRM subset already feasible for SSM?

(3) What are the current limitations of in situ observations that limit fiduciality?

(4) What is needed to create a full traceability chain from in situ point measurements to the satellite footprint scale?

In this presentation, we will discuss these questions in detail and report on related findings of the FRM4SM project.

How to cite: Himmelbauer, I., Gruber, A., Aberer, D., Preimesberger, W., Stradiotti, P., Dorigo, W. A., Boresch, A., Tercjak, M., Gibon, F., Mialon, A., Richaume, P., Kerr, Y., Diez Garcia, R., Crapolicchio, R., Sabia, R., Scipal, K., and Goryl, P.: Analyzing the reliability of in situ soil moisture measurements for satellite product validation: What makes fiducial reference measurements fiducial?, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-16006,, 2023.