Abstract. In the recent years, the German federal state of Brandenburg has been particularly impacted by soil moisture droughts. To support the timely and informed management of such water-related risks, we introduce a novel soil moisture monitoring network based on cosmic-ray neutron sensing (CRNS) technology. Driven by a joint collaboration of research institutions and federal state agencies, eight sites across Brandenburg were instrumented by 2024 (four more were deployed by the end of 2025). The data is openly accessible in order to foster applications and collaboration right from the start. In this paper, we present the network design, evaluate and discuss the CRNS-based soil moisture estimates from 2024 until 2025, and demonstrate how the observations from this network can serve to evaluate and improve soil moisture products with regard to their applicability in Brandenburg. Specifically, we compare selected large-scale products from modelling and remote sensing (ERA5-Land, the Soil Water Index of the Copernicus Land Monitoring Service, and the Copernicus Climate Change Service surface soil moisture product) to the Soil-Water-Atmosphere-Plant (SWAP) model that was set up based on region-specific data. We conclude that model-based products (ERA5-Land and, in particular, the region-specific SWAP model) have the highest potential to mitigate the inherent limitations of a sparse instrumental soil moisture network (such as limited temporal, horizontal and vertical coverage). We further discuss resulting implications for the management of water-related risks in Brandenburg, practical lessons learned from the establishment and operation of the network, as well as potential future applications.
Heistermann et al. (Fri,) studied this question.