Understanding the influence of landscape heterogeneities on the signal of cosmic-ray neutron sensors by means of site-specific neutron transport simulation

Monitoring soil moisture is a challenging task due to its complex spatial patterns. In recent years, cosmic-ray neutron sensing has gained popularity for its ability to provide integral measurements over a few hectares horizontally and a few decimeters vertically, covering a representative volume for many research questions in various landscapes. However, interpreting signals using averaging methods becomes increasingly difficult as the heterogeneity of the observable increases.
As part of the SoMMet project, three field sites in Germany and Italy equipped with cosmic-ray neutron sensors are analyzed in detail using the Monte Carlo code URANOS. The virtual representation of these sites in the code allows for removing and adding structures. Thereby, all features of the landscape of the three different sites can be examined separately with respect to their impact on the local neutron field. These include general landscape heterogeneities, buildings, land use, and biomass. While this study focuses on three specific, although relatively common, site setups, it also offers general insights that can enhance the understanding of signal and footprint dynamics at other locations.