We invite presentations concerning remote sensing of soil moisture, field experiments, data assimilation, Cal/Val activities and fiducial reference measurements (FRMs).
Remote sensing has made tremendous progress to provide robust estimates of soil moisture at different depths and scales. Field or aircraft experiments have been organised to improve our understanding of active and passive microwave soil moisture sensing, including the effects of soil roughness, vegetation, spatial heterogeneities, and topography. At global scale, instruments such as SMMR (1978-1987), AMSR (2002-), ERS/SCAT (1992-2000) provided information on surface soil moisture. Current L-band sensors such as SMOS (2009-) and SMAP (2015-), and active C-band observations with the Metop/ASCAT series (2006-) and Sentinel-1, also enable an accurate quantification of the soil moisture. Operational programmes like Copernicus and novel developments will further enhance our capabilities to monitor soil moisture from agricultural to climate scales. Furthermore, research has put a new focus on establishing rigorous guidelines for the installation, calibration, operation, maintenance, and use of in situ soil moisture measurements using metrological practices, as well as on the development of advanced quality control procedures for in situ soil moisture measurement networks to obtain so-called fiducial reference measurements (FRMs).

We encourage submissions related to soil moisture remote sensing, including:
- Field experiments and theoretical advances in microwave modelling
- High spatial resolution soil moisture estimation based on, e.g., Sentinel observations, GNSS reflections, or using novel downscaling methods.
- Preparation of future missions including passive L-band high resolution concepts, CIMR, Metop-SG/SCA, NISAR....
- Root zone soil moisture retrieval and soil moisture data assimilation in land surface models, hydrological models and in Numerical Weather Prediction models.
- Evaluation and trend analysis of soil moisture climate data records.
- Inter-comparison and inter-validation between land surface models, remote sensing approaches and in-situ validation networks.
- Uncertainty characterization across scales and progress towards traceable uncertainty budgets in particular for data assimilation
- Soil moisture reference networks, especially the establishment of FRMs.
- Application of satellite soil moisture products for improving hydrological and other applications.