We are in the process of migrating all NASA Earth science data sites into Earthdata from now until end of 2026. Not all NASA Earth science data and resources will appear here until then. Thank you for your patience as we make this transition.Read about the Web Unification Project
Description
This enhanced Level-3 (L3) soil moisture product provides a composite of daily estimates of global land surface conditions retrieved by the Soil Moisture Active Passive (SMAP) radiometer. This product is a daily composite of SMAP Level-2 (L2) soil moisture which is derived from SMAP Level-1C (L1C) interpolated brightness temperatures. Backus-Gilbert optimal interpolation techniques are used to extract information from SMAP antenna temperatures and convert them to brightness temperatures, which are posted to the 9 km Equal-Area Scalable Earth Grid, Version 2.0 (EASE-Grid 2.0) in a global cylindrical projection. As of 2021, the data are also posted to the Northern Hemisphere EASE-Grid 2.0, an azimuthal equal-area projection.
Version Description
Changes to this version include:
• An improved processing methodology was applied to the input enhanced Level-2 radiometer brightness temperatures.
• The data algorithms, structure, content, or processor code are otherwise unchanged from the previous version.
For the full major and minor version history, go to https://nsidc.org/data/smap/version-history
Citation is critically important for dataset documentation and discovery. This dataset is openly shared, without restriction, in accordance with the EOSDIS Data Use and Citation Guidance.
Copy Citation
Citation Copied
ONeill, P., Chan, S., Njoku, E., Jackson, T., Bindlish, R., Chaubell, J., & Colliander, A. (2023). SMAP Enhanced L3 Radiometer Global and Polar Grid Daily 9 km EASE-Grid Soil Moisture, Version 6 [Data set]. NASA National Snow and Ice Data Center Distributed Active Archive Center. https://doi.org/10.5067/M20OXIZHY3RJ Date Accessed: 2026-05-01
ONeill, Peggy, Steven Chan, Eni Njoku, Thomas Jackson, Rajat Bindlish, Julian Chaubell, and Andreas Colliander. “SMAP Enhanced L3 Radiometer Global and Polar Grid Daily 9 Km EASE-Grid Soil Moisture, Version 6.” NASA National Snow and Ice Data Center Distributed Active Archive Center, 2023. doi:10.5067/M20OXIZHY3RJ. Date Accessed: 2026-05-01
ONeill, Peggy, et al. SMAP Enhanced L3 Radiometer Global and Polar Grid Daily 9 Km EASE-Grid Soil Moisture, Version 6. NASA National Snow and Ice Data Center Distributed Active Archive Center, 2023, doi:10.5067/M20OXIZHY3RJ. Date Accessed: 2026-05-01
Brightness Temperature, Surface Soil Moisture, Gross Primary Production (gpp), Heterotrophic Respiration (rh), NET ECOSYSTEM CO2 EXCHANGE (NEE), Soil Organic Carbon (SOC)
A satellite-driven approach to estimating delivered irrigation water via SM-based inversion algorithm: A case study of the Doroodzan irrigation district, Iran