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Description

This Level-2 (L2) soil moisture product provides estimates of land surface conditions retrieved by both the Soil Moisture Active Passive (SMAP) radiometer during 6:00 a.m. descending and 6:00 p.m. ascending half-orbit passes and the Sentinel-1A and -1B radar. SMAP L-band brightness temperatures and Copernicus Sentinel-1 C-band backscatter coefficients are used to derive soil moisture data, which are then resampled to an Earth-fixed, cylindrical 3 km Equal-Area Scalable Earth Grid, Version 2.0 (EASE-Grid 2.0).

<b>Note:</b> These data are Beta-release quality, meaning that they have not undergone full validation and may still contain significant errors.

Version Description

Changes to this version include:

  • Implemented a new method of identifying and eliminating spurious sigma0 values in Sentinel-1A/B Level-1 sigma0 data using a hybrid approach that combines a median filter with thresholding. As a result, fewer spurious sigma0 values (mainly due to small man-made structures) bias the aggregated 1 km data.
  • Replaced the previous 3 km resolution urban fraction map with a new 1 km map.
  • Adjusted the thresholds used with the new 1 km urban fraction map to: 0.25 (no flag), 0.25 – 0.5 (flagged, retrieval performed), and 0.5 (masked, no retrieval). These are provided in bit 3 of the surface_flag data field.
  • Adjusted the tau-omega parameters to be consistent with the values used in SPL2SMP/SPL2SMP_E algorithm.
  • Implemented minor bug fix to the SMAP and Sentinel-1 overlap computation code.
For the full major and minor version history, go to https://nsidc.org/data/smap/version-history

Product Summary

Platforms
Sentinel-1A ,
Sentinel-1B ,
SMAP
Instruments
C-SAR ,
SMAP L-BAND RADIOMETER
Spatial Extent

N: 60 S: -60 E: 180 W: -180

Spatial Resolution
3 Kilometers x 3 Kilometers
Spatial Reference System(s)
WGS 84 / NSIDC EASE-Grid 2.0 Global (EPSG:6933)
Location
OCEANIA ,
AFRICA ,
ASIA ,
EUROPE ,
NORTH AMERICA ,
SOUTH AMERICA
Coordinate System
CARTESIAN
Granule Spatial Representation
GEODETIC
Temporal Extent
2015-03-31 to 2020-08-26
Temporal Resolution
30 Second
Concept ID
C2812932846-NSIDC_CPRD
Data State
DEPRECATED
Number of Files/Granules
0
Processing Level
2
Published
Updated
Science Keywords
Soil Moisture/Water Content

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

Das, N., Entekhabi, D., Dunbar, R., Kim, S., Yueh, S., Colliander, A., ONeill, P., Jackson, T., Jagdhuber, T., Chen, F., Crow, W., Walker, J., Berg, A., Bosch, D., Caldwell, T., & Cosh, M. (2018). SMAP/Sentinel-1 L2 Radiometer/Radar 30-Second Scene 3 km EASE-Grid Soil Moisture, Version 2 [Dataset]. NASA National Snow and Ice Data Center Distributed Active Archive Center. https://doi.org/10.5067/KE1CSVXMI95Y Date Accessed: 2026-07-16

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