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Description
This 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) passive microwave radiometer. SMAP L-band soil moisture data are resampled to a global, cylindrical 36 km Equal-Area Scalable Earth Grid, Version 2.0 (EASE-Grid 2.0).
Version Description
Changes to this version include:
- Improved calibration methodology was applied to the Level-1B radiometer brightness temperatures.
- Improved land surface model outputs from the NASA Global Modeling and Assimilation Office (GMAO) were used to estimate the effective soil temperature used as input to Level-2 soil moisture geophysical inversion. This effective soil temperature is not to be confused with the physical soil temperature at a given depth (Choudhury et al., 1982).
- Improved retrieval performance of DCA (formerly known as MDCA or "the option 3" option algorithm in previous releases). DCA retrieves both soil moisture and vegetation optical depth (VOD or tau).
- Use of a new global 250-meter resolution soils database called SoilGrid250m available at https://openlandmap.org. Work is underway to address limited spatial anomalies of these soil property estimates at high latitudes over areas rich in organic soils.
- Added 30 new soil moisture retrieval fields associated with the two optional algorithms used in Level-2 soil moisture processing.
- Data quality flags were updated and corrected where faulty.
- The baseline algorithm (SCA-V) remains unchanged.
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.
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ONeill, P., Chan, S., Njoku, E., Jackson, T., Bindlish, R., & Chaubell, J. (2020). SMAP L3 Radiometer Global Daily 36 km EASE-Grid Soil Moisture, Version 7 [Data set]. NASA National Snow and Ice Data Center Distributed Active Archive Center. https://doi.org/10.5067/HH4SZ2PXSP6A Date Accessed: 2026-06-10
ONeill, Peggy, Steven Chan, Eni Njoku, Thomas Jackson, Rajat Bindlish, and Julian Chaubell. “SMAP L3 Radiometer Global Daily 36 Km EASE-Grid Soil Moisture, Version 7.” NASA National Snow and Ice Data Center Distributed Active Archive Center, 2020. doi:10.5067/HH4SZ2PXSP6A. Date Accessed: 2026-06-10
ONeill, Peggy, et al. SMAP L3 Radiometer Global Daily 36 Km EASE-Grid Soil Moisture, Version 7. NASA National Snow and Ice Data Center Distributed Active Archive Center, 2020, doi:10.5067/HH4SZ2PXSP6A. Date Accessed: 2026-06-10