Abstract
Synthetic aperture radar (SAR) is a remote sensing technique for mapping of soil moisture with high spatial resolution. C -band SAR can resolve features at field scale, or better, but responds to moisture only within the top 1 to 2 cm of the soil. When validating SAR-derived soil moisture products against standard in situ measurements at 5 to 10 cm depth, the greater moisture variability at the soil surface may be inaccurately categorized as measurement error. An alternative method was developed where the C -band SAR product is validated against soil moisture simulated at 2 cm depth by the HYDRUS-1D model. This reproduces soil moisture depth profiles from daily meteorological observations, leaf area index, and soil hydraulic parameters. The model was fitted at 13 COSMOS-UK sites so that the model output at 10 cm depth closely reproduced the cosmic ray neutron sensor data. At ten of the sites studied, there was an improvement of up to 8% in root-mean-squared difference by validating the Copernicus surface soil moisture (SSM) product at 2 cm compared to 10 cm. This suggests that Copernicus SSM and other C -band SAR surface soil moisture algorithms may be more accurate than have hitherto been acknowledged.
Highlights
S OIL moisture remote sensing is of significant interest to agriculture, hydrological modeling, and weather forecasting
This shows the final values of the soil hydraulic parameters after optimization and the values of dr
The results provided enough confidence in the model to use it at a shallower soil depth
Summary
S OIL moisture remote sensing is of significant interest to agriculture, hydrological modeling, and weather forecasting. Satellite active microwave systems have the ability to operate over wide areas in almost all weather conditions, with C-band synthetic aperture radar (SAR) systems being able to achieve field-scale resolution or better. Soil moisture estimation by SAR exploits the dependence of radar backscatter on soil water content, but there are other dependencies on factors that are often unknown. These include soil texture, surface roughness, topography, and the effect of vegetation. COSMOSUK is supported by the Natural Environment Research Council under Award NE/R016429/1 as part of the U.K.-SCAPE programme delivering National Capability. COSMOSUK is supported by the Natural Environment Research Council under Award NE/R016429/1 as part of the U.K.-SCAPE programme delivering National Capability. (Corresponding author: John Beale.)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
