The SEiSMo project addresses the current major challenge in MetOp ASCAT soil moisture retrievals: subsurface scattering. This phenomenon occurs when radar signals penetrate dry soils and are reflected not only by the surface but also by stones, rocks, or soil layers beneath, resulting in elevated backscatter under prolonged dry conditions. This breaks the long-standing assumption that backscatter increases monotonically with soil moisture, making it impossible to unambiguously link a given backscatter value to a unique soil moisture state. Such effects currently cause major retrieval errors not only in desert regions but also in more humid climates with a dry season. Building on TU Wien’s long-standing expertise on this subject, the project develops and applies new models to capture the complexity of subsurface scattering, enabling correct soil moisture retrievals. In addition, it introduces methods for automatically detecting subsurface scattering, thereby resolving ambiguities in soil moisture estimates. By advancing the TU Wien change detection model, SEiSMo aims to enhance both the correctness and availability of ASCAT and future SCA soil moisture products, ultimately strengthening EUMETSAT’s H SAF services for applications such as hydrology, climate monitoring, and water management.