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Description

SMAP Level-4 (L4) surface and root zone soil moisture data are provided in three products: (1) SMAP L4 9 km EASE-Grid Surface and Root Zone Soil Moisture Geophysical Data (SPL4SMGP). (2) SMAP L4 9 km EASE-Grid Surface and Root Zone Soil Moisture Analysis Update (SPL4SMAU). (3) SMAP L4 9 km EASE-Grid Surface and Root Zone Soil Moisture Land Model Constants (SPL4SMLM).

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 (1) SMAP observations are now assimilated in Eastern Europe, the Middle East, and East Asia due to expanded coverage of the brightness temperature scaling parameters. The latter are based on two years of SMAP Version 3 brightness temperature observations where the SMOS climatology is unavailable due to RFI. (2) An improved version of the model-only Nature Run (NRv4.1) simulation is used to derive the brightness temperature scaling parameters, the model soil moisture initial conditions, and the soil moisture climatology. (3) Minor bug fixes.

Product Summary

Platforms
SMAP
Instruments
SMAP L-BAND RADAR
Spatial Extent

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

Spatial Resolution
9 Kilometers x 9 Kilometers
Location
GLOBAL LAND
Coordinate System
CARTESIAN
Granule Spatial Representation
CARTESIAN
Temporal Extent
2015-03-31
Concept ID
C4114263189-NSIDC_CPRD
Data State
DEPRECATED
Number of Files/Granules
0
Processing Level
4
Published
Science Keywords
Soil Classification ,
Soil Depth ,
Soil Porosity ,
Soil Texture ,
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. (2017). SMAP L4 9 km EASE-Grid Surface and Root Zone Soil Moisture Land Model Constants, Version 3 [Dataset]. NASA National Snow and Ice Data Center Distributed Active Archive Center. https://doi.org/10.5067/4IYTBSUKM57Q Date Accessed: 2026-06-08

Documents

Publications Citing This Dataset

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Title Year Author Topic
Global estimates of daily evapotranspiration using SMAP surface and root-zone soil moisture Kim, Youngwook, Park, Hotaek, Kimball, John S., Colliander, Andreas, McCabe, Matthew F. Surface Pressure, Heat Flux, Longwave Radiation, Shortwave Radiation, Surface Temperature, Humidity, Evapotranspiration, Surface Winds, Rain, Precipitation Rate, Snow, Soil Moisture/Water Content, Soil Temperature, Land Surface Temperature, Snow Water Equivalent, Runoff, Soil Porosity, Carbon, Organic Matter, Soil Chemistry, Soil Ph, Water Table, Vegetation Cover, Soil Classification, Geomorphic Landforms/Processes, Land Use/Land Cover Classification, Soil Bulk Density, Soil Classification, Soil Color, Soil Depth, Soil Horizons/Profile, Soil Structure, Drainage, Soil Texture, Terrain Elevation, Surface Soil Moisture, Freeze/Thaw
Impact of Incidence Angle Diversity on SMOS and Sentinel-1 Soil Moisture Retrievals at Coarse and Fine Scales Portal, Gerard, Vall-llossera, Merce, Piles, Maria, Jagdhuber, Thomas, Camps, Adriano, Pablos, Miriam, Lopez-Martinez, Carlos, Das, Narendra N., Entekhabi, Dara Land Use/Land Cover Classification, Plant Phenology, Enhanced Vegetation Index (EVI), Brightness Temperature, SIGMA NAUGHT, Surface Soil Moisture, Terrain Elevation
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