Validation practices for satellite soil moisture retrievals: What are (the) errors?
Alexander Gruber, Gabriëlle De Lannoy, Clément Albergel, Amen Al‐Yaari, Luca Brocca, Jean‐Christophe Calvet, Andreas Colliander, Michael H. Cosh, Wade T. Crow, Wouter Dorigo, Clara Draper, Martin Hirschi, Yann H. Kerr, Alexandra G. Konings, W. A. Lahoz, Kaighin A. McColl, Carsten Montzka, Joaquín Muñoz‐Sabater, Jian Peng, Rolf H. Reichle, Philippe Richaume, Christoph Rüdiger, Tracy Scanlon, Robin van der Schalie, Jean‐Pierre Wigneron, Wolfgang Wagner
Abstract
This paper presents a community effort to develop good practice guidelines for the validation of global coarse-scale satellite soil moisture products. We provide theoretical background, a review of state-of-the-art methodologies for estimating errors in soil moisture data sets, practical recommendations on data pre-processing and presentation of statistical results, and a recommended validation protocol that is supplemented with an example validation exercise focused on microwave-based surface soil moisture products. We conclude by identifying research gaps that should be addressed in the near future.