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Description

SMAP Level-4 (L4) surface and root zone soil moisture data are provided in three products:

  • SMAP L4 Global 3-hourly 9 km EASE-Grid Surface and Root Zone Soil Moisture Geophysical Data (SPL4SMGP, DOI: 10.5067/KPJNN2GI1DQR)
  • SMAP L4 Global 3-hourly 9 km EASE-Grid Surface and Root Zone Soil Moisture Analysis Update (SPL4SMAU, DOI: 10.5067/60HB8VIP2T8W)
  • SMAP L4 Global 9 km EASE-Grid Surface and Root Zone Soil Moisture Land Model Constants (SPL4SMLM, DOI: 10.5067/KGLC3UH4TMAQ).
    For each product, SMAP L-band brightness temperature data from descending and ascending half-orbit satellite passes (approximately 6:00 a.m. and 6:00 p.m. local solar time, respectively) are assimilated into a land surface model that is gridded using an Earth-fixed, global cylindrical 9 km Equal-Area Scalable Earth Grid, Version 2.0 (EASE-Grid 2.0) projection.

Version Description

Changes to this version include: Revisions to the land surface modeling system; Revisions to the parameters and parameterizations of the surface energy balance and the snow depletion curve; Analysis increments are no longer computed for the “catchment deficit” model prognostic variable in the Ensemble Kalman filter update step; Added x and y coordinate variables as well as an EASE-Grid 2.0 projection grid mapping variable; Minor bug fixes. For the full major and minor version history, go to https://nsidc.org/data/smap/data_versions.

Product Summary

Platforms
SMAP
Instruments
SMAP L-BAND RADIOMETER
Spatial Extent

N: 85.044 S: -85.044 E: 180 W: -180

Spatial Resolution
9 Kilometers x 9 Kilometers
Spatial Reference System(s)
WGS 84 / NSIDC EASE-Grid 2.0 Global (EPSG:6933)
Location
GLOBAL LAND
Coordinate System
CARTESIAN
Granule Spatial Representation
CARTESIAN
Temporal Extent
2015-03-31 to 2020-08-27
Concept ID
C2872768472-NSIDC_CPRD
Data State
DEPRECATED
Number of Files/Granules
0
Processing Level
4
Published
Updated
Science Keywords
Terrain Elevation

Citation

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

Reichle, R., De Lannoy, G., Koster, R., Crow, W., Kimball, J., & Liu, Q. (2018). SMAP L4 Global 9 km EASE-Grid Surface and Root Zone Soil Moisture Land Model Constants, Version 4 [Dataset]. NASA National Snow and Ice Data Center Distributed Active Archive Center. https://doi.org/10.5067/KGLC3UH4TMAQ Date Accessed: 2026-08-01

Documents

Publications Citing This Dataset

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Title Year Author Topic
Reconciling remote sensing and reanalysis land surface temperatures: How surface conditions shape systematic differences between GOES-16 and MERRA-2 across ... Kathuria, Dhruva, Konings, Alexandra G., Kolassa, Jana, Liu, Yanlan, Zhao, Meng, Shiklomanov, Alexey N Leaf Characteristics, Photosynthetically Active Radiation, Leaf Area Index (LAI), Fraction Of Absorbed Photosynthetically Active Radiation (fapar), Terrain Elevation
The Coupling of Soil Water and Leaf Phenology Observed by Satellite During Australian Bushfires in 20192020 Liu, Yuqing, Shi, Wenzhong, Zhang, Min, Hao, Ming, Zhang, Hua, Sun, Yangjie Canopy Characteristics, Evergreen Vegetation, Crown, Deciduous Vegetation, Leaf Characteristics, Vegetation Cover, Land Use/Land Cover Classification, Terrain Elevation, Total Surface Precipitation Rate, Fire Occurrence, Surface Thermal Properties, Land Surface Temperature, THERMAL ANOMALIES, Evapotranspiration, Latent Heat Flux, Fraction Of Absorbed Photosynthetically Active Radiation (fapar), Leaf Area Index (LAI), Vegetation Index, Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI)
Simulating land-atmosphere coupling in the Central Valley, California: Investigating soil moisture impacts on boundary layer properties Alexander, G. Aaron, Holmes, Heather A., Sun, Xia, Caputi, Dani, Faloona, Ian C., Oldroyd, Holly J. Surface Soil Moisture, Terrain Elevation
The benefit of brightness temperature assimilation for the SMAP Level-4 surface and root-zone soil moisture analysis Qiu, Jianxiu, Dong, Jianzhi, Crow, Wade T., Zhang, Xiaohu, Reichle, Rolf H., De Lannoy, Gabrielle J. M. Brightness Temperature, Surface Soil Moisture, Terrain Elevation
Plant water uptake thresholds inferred from satellite soil moisture Bassiouni, Maoya, Good, Stephen P., Still, Christopher J., Higgins, Chad W. Surface Soil Moisture, Brightness Temperature, Soil Moisture/Water Content, Terrain Elevation
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