COSMIC-RAY NEUTRON PROBES FOR SATELLITE SOIL MOISTURE VALIDATION

Low resolution satellite products are often validated by point-scale in-situ soil moisture measurements from TDR/FDR devices, where the scale mismatch limits the quality of validation efforts in heterogeneous regions. In Cosmic Ray Neutron Probes (CRNP) provide area-average soil moisture within a 150 - 250 m radius footprint, so that they are able to fill the scale gap between both systems. In this study we evaluate differences and communalities between CRNP observations, and surface soil moisture products from the Advanced Microwave Scanning Radiometer 2 (AMSR2), the METOP-A/B Advanced Scatterometer (ASCAT), the Soil Moisture Active and Passive (SMAP), the Soil Moisture and Ocean Salinity (SMOS), as well as simulations from the Global Land Data Assimilation System Version 2 (GLDAS2). CRNPs within the Rur catchment in Germany have been selected for comparison. Standard validation scores identified SMAP to provide a high accuracy soil moisture product with low noise or uncertainties as compared to CRNPs.