EGU21-1379, updated on 19 Dec 2023
EGU General Assembly 2021
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Exploring trends for the H SAF ASCAT root-zone soil moisture data records

David Fairbairn, Patricia de Rosnay, and Peter Weston
David Fairbairn et al.
  • ECMWF, Earth system assimilation, Reading, United Kingdom of Great Britain – England, Scotland, Wales (

Environmental (e.g. floods, droughts) and weather prediction systems rely on an accurate representation of soil moisture (SM). The EUMETSAT H SAF aims to provide high quality satellite-based hydrological products, including SM.
ECMWF is producing ASCAT root zone SM for H SAF. The production relies on an Extended Kalman filter to retrieve root zone SM from surface SM satellite data. A 10 km sampling reanalysis product (1992-2020) forced by ERA5 atmospheric fields (H141/H142) is produced for H SAF, which assimilates ERS/SCAT (1992-2006) and ASCAT-A/B/C (2007-2020) derived surface SM. The root-zone SM performance is validated using sparse in situ observations globally and generally demonstrates a positive and consistent correlation over the period. A negative trend in root-zone SM is found during summer and autumn months over much of Europe during the period (1992-2020). This is consistent with expected climate change impacts and is particularly alarming over the water-scarce Mediterranean region. The recent hot and dry summer of 2019 and dry spring of 2020 are well captured by negative root-zone SM anomalies. Plans for the future H SAF data record products will be presented, including the assimilation of high-resolution EPS-SCA-derived soil moisture data.

How to cite: Fairbairn, D., de Rosnay, P., and Weston, P.: Exploring trends for the H SAF ASCAT root-zone soil moisture data records, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1379,, 2021.