Roadmap for leveraging satellite data to advance soil moisture monitoring in Mainland Southeast Asia

Soil moisture monitoring is vital for Mainland Southeast Asia (MSEA), a region that plays a pivotal role in global agricultural production. Strong reliance on rain‐fed agriculture, combined with frequent hydroclimatic extremes, makes MSEA one of the world's most climate‐sensitive regions. Accurate soil moisture information is therefore essential for strengthening agricultural resilience and climate disaster preparedness. Although in situ soil moisture observations provide high accuracy, MSEA lacks comprehensive, long‐term monitoring networks. Satellite soil moisture products offer broad coverage but are constrained by persistent data gaps arising from missing satellite overpasses, radio‐frequency interference, and dense vegetation cover, and by coarse spatial (25–50 km) and temporal (2–3 day) resolutions that fall short of operational requirements (<200 m, <daily). In MSEA, its practical adoption remains limited by low stakeholder awareness and sparse ground‐based validation networks. Emerging efforts, including a pilot initiative to regionally validate high‐resolution soil moisture products from the Soil Moisture Active Passive and NASA–ISRO's (National Aeronautics and Space Administration–Indian Space Research Organization) Synthetic Aperture Radar missions indicate growing momentum. This paper proposes a roadmap for advancing satellite‐based soil moisture monitoring in MSEA, structured around four pillars: (1) mitigating data gaps and region‐specific validation, (2) improving spatiotemporal resolution, (3) deriving multi‐depth soil moisture estimates, and (4) strengthening regional capacity on soil moisture applications. A central contribution of this roadmap is the delineation of 20 representative land cover–climate combinations to inform the design of validation sites in the region. The roadmap aims to guide researchers, practitioners, and policymakers toward developing regionally validated, high‐resolution soil moisture products to support effective decision‐making in MSEA.