Exploring Three-dimensional Soil Moisture Variability using Multi-Source Observations

Soil moisture is a fundamental state variable governing land–atmosphere interactions and hydrological responses to extreme climate events. Although satellite remote sensing has substantially improved the spatial coverage of surface soil moisture observations, most existing products remain confined to the near-surface layer, limiting their applicability to subsurface hydrological processes. The absence of depth-resolved soil moisture information remains a key challenge for representing infiltration, drainage, and root-zone dynamics. This study examines the potential for advancing soil moisture characterization toward three-dimensional (3D) spatial representations by exploiting the complementary information content of multi-source observations. Spatially continuous surface soil moisture fields provide valuable insights into horizontal variability, whereas ground-based measurements offer essential constraints on vertical soil moisture structure. By investigating soil moisture variability across depth and space under varying hydrometeorological conditions, this work highlights the role of subsurface information in improving the interpretation of surface soil moisture patterns. Rather than presenting finalized estimates, this study adopts an exploratory perspective to emphasize the conceptual importance of incorporating subsurface soil moisture into spatial analyses. The findings aim to contribute to ongoing efforts to improve soil moisture representation for hydrological modeling and to inform future applications in flood and drought assessment using 3D soil moisture frameworks.

 

Keywords: Soil Moisture, Subsurface process, Hydrological extremes

 

Acknowledgment

This research was supported by the BK21 FOUR (Fostering Outstanding Universities for Research) funded by the Ministry of Education (MOE, Korea) and National Research Foundation of Korea (NRF). This work is financially supported by Korea Ministry of Land, Infrastructure and Transport (MOLIT) as 「Innovative Talent Education Program for Smart City」. This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (RS-2022-NR070339). This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (RS-2024-00416443). This work was supported by Korea Environment Industry & Technology Institute(KEITI) through Water Management Program for Drought Project, funded by Korea Ministry of Climate, Energy and Environment(MCEE)(RS-2023-00230286). This work was supported by Korea Environment Industry & Technology Institute (KEITI) through Research and Development on the Technology for Securing the Water Resources Stability in Response to Future Change Project, funded by Korea Ministry of Climate, Energy and Environment(MCEE)(RS-2024-00332300).