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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). While the 3 km data product has undergone validation, the 1 km product has not and should be used with caution.

Version Description

Changes to this version include: - An improved calibration methodology was applied to the SMAP Level-1B brightness temperatures. - Revised the coefficients in the land surface temperature computation to be consistent with the SMAP Level-2 soil moisture passive enhanced product. The new coefficients are C=0.246, K=1.007 for AM passes and C=1.0, K=1.007 for PM passes. - Changed the omega parameter of the tau-omega model for forest landcover classes (1-5) from 0.05 to 0.07. - Uses a new high-resolution soil database (SoilGrid250m; Hengl et al., 2017). - Uses bulk density to set the upper limit of the soil moisture retrievals. Previous versions used a fixed value of 0.65 m3/m3. - Enhanced documentation on Data Flags in the User Guide to help data users to better understand and use the flags. - Added a bit in the TB Disaggregation QC flag to indicate (1) the use of SMAP AM or PM data; and (2) the time difference (greater or less than 36 hours) between the SMAP and Sentinel observations overlap. - Fixed the EASE_[row/column]_index_apm_[1km/3km] data fields to make them 0-based. - Fixed the range beginning and ending time in the file metadata. For the full major and minor version history, go to https://nsidc.org/data/smap/version-history

Product Summary

Platforms
SMAP ,
SENTINEL-1A ,
SENTINEL-1B
Instruments
SMAP L-BAND RADIOMETER ,
C-SAR
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 Present
Temporal Resolution
30 Second
Concept ID
C2938663471-NSIDC_CPRD
Data State
ACTIVE
Number of Files/Granules
1832243
Processing Level
2
Published
Updated
Science Keywords
Brightness Temperature ,
SIGMA NAUGHT ,
Surface Soil Moisture

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. (2020). SMAP/Sentinel-1 L2 Radiometer/Radar 30-Second Scene 3 km EASE-Grid Soil Moisture, Version 3 [Dataset]. NASA National Snow and Ice Data Center Distributed Active Archive Center. https://doi.org/10.5067/ASB0EQO2LYJV Date Accessed: 2026-08-24

Documents

Publications Citing This Dataset

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Title Year Author Topic
Soil Moisture: analysis of SMAP satellite products in plain zones Degano, Maria Florencia, Beninato, Sabrina, Holzman, Mauro Ezequiel, Bayala, Martin Ignacio, Rivas, Raul Eduardo, Massari, Christian Surface Soil Moisture, Brightness Temperature, Soil Moisture/Water Content
A novel land surface temperature reconstruction method and its application for downscaling surface soil moisture with machine learning Gungor Sahin, Onur, Gunduz, Orhan Vegetation Index, Normalized Difference Vegetation Index (NDVI), Plant Phenology, Enhanced Vegetation Index (EVI), Land Surface Temperature, Emissivity, Reflectance, Brightness Temperature, SIGMA NAUGHT, Soil Moisture/Water Content, Root Zone Soil Moisture, Surface Soil Moisture
Soil Moisture Prediction Using NDVI and NSMI Satellite Data: ViT-Based Models and ConvLSTM-Based Model Habiboullah, Amina, Louly, Mohamed Abdellahi Soil Moisture/Water Content
Thermal hydraulic disaggregation of SMAP soil moisture over the continental United States Liu, Pang-Wei, Bindlish, Rajat, O'Neill, Peggy, Fang, Bin, Lakshmi, Venkat, Yang, Zhengwei, Cosh, Michael H., Bongiovanni, Tara, Collins, Chandra Holifield, Starks, Patrick J., Prueger, John, Bosch, David D., Seyfried, Mark, Williams, Mark R. Land Surface Temperature, Emissivity, Vegetation Index, Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), Soil Moisture/Water Content, Surface Soil Moisture
Soil Moisture Prediction Based on Satellite Data Using a Novel Deep Learning Model Habiboullah, Amina, Louly, Mohamed Abdellahi Soil Moisture/Water Content
Downscaling SMAP soil moisture using a wide & deep learning method over the Continental United States Xu, Mengyuan, Yao, Ning, Yang, Haoxuan, Xu, Jia, Hu, Annan, Gustavo Goncalves de Goncalves, Luis, Liu, Gang Land Surface Temperature, Emissivity, Soil Moisture/Water Content
A Method to Estimate Surface Soil Moisture and Map the Irrigated Rabiei, Saman, Jalilvand, Ehsan, Tajrishy, Massoud Soil Moisture/Water Content
Neural Network Integration of SMAP and Sentinel-1 for Estimating Soil Moisture at High Spatial Resolution Santi, E., Paloscia, S., Pettinato, S., Fontanelli, G. Soil Moisture/Water Content
Remote Sensing for Agriculture Gao, Feng Soil Moisture/Water Content
Assessing disaggregated SMAP soil moisture products in the United States Liu, Pang-Wei, Bindlish, Rajat, Fang, Bin, Lakshmi, Venkat, O'Neill, Peggy E., Yang, Zhengwei, Cosh, Michael H., Bongiovanni, Tara, Bosch, David D., Collins, Chandra Holifield, Starks, Patrick J., Prueger, John, Seyfried, Mark, Livingston, Stanley Land Surface Temperature, Emissivity, Vegetation Index, Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), Soil Moisture/Water Content, Surface Soil Moisture
On the runoff validation of 'Global BROOK90'automatic modeling framework Vorobevskii, Ivan, Kronenberg, Rico, Bernhofer, Christian RADAR IMAGERY, Terrain Elevation, Topographical Relief Maps, Digital Elevation/Terrain Model (DEM), Soil Moisture/Water Content
Effects of lateral flow on the convective environment in a coupled hydrometeorological modeling system in a semiarid environment Lahmers, Timothy M., Castro, Christopher L., Hazenberg, Pieter Soil Moisture/Water Content
Evaluation of SMAP Level 2, 3, and 4 Soil Moisture Datasets over the Xu, Xiaoyong Surface Soil Moisture, Soil Moisture/Water Content
Prediction of large-scale wildfires with the canopy stress index derived from soil moisture active passive Lee, Ju Hyoung Soil Moisture/Water Content
Soil moisture content from GNSS reflectometry using dielectric permittivity from fresnel reflection coefficients Calabia, Andres, Molina, Inigo, Jin, Shuanggen Radar Cross-Section, Radar Reflectivity, SIGMA NAUGHT, Flight Data Logs, Soil Moisture/Water Content, Terrain Elevation, Vegetation Height
SMOS brightness temperature forward modelling and long term monitoring at ECMWF de Rosnay, Patricia, Munoz-Sabater, Joaquin, Albergel, Clement, Isaksen, Lars, English, Stephen, Drusch, Matthias, Wigneron, Jean-Pierre Soil Moisture/Water Content
Continental drought monitoring using satellite soil moisture, data assimilation and an integrated drought index Xu, Lei, Abbaszadeh, Peyman, Moradkhani, Hamid, Chen, Nengcheng, Zhang, Xiang Evapotranspiration, Latent Heat Flux, Soil Moisture/Water Content
Downscaling SMAP soil moisture estimation with gradient boosting decision tree regression over the Tibetan Plateau Wei, Zushuai, Meng, Yizhuo, Zhang, Wen, Peng, Jian, Meng, Lingkui Soil Moisture/Water Content
Gap filling of highresolution soil moisture for SMAP/sentinel1: a twolayer machine learningbased framework Mao, Hanzi, Kathuria, Dhruva, Duffield, Nick, Mohanty, Binayak P. Soil Moisture/Water Content, RADAR IMAGERY, Terrain Elevation, Digital Elevation/Terrain Model (DEM), Leaf Characteristics, Photosynthetically Active Radiation, Leaf Area Index (LAI), Fraction Of Absorbed Photosynthetically Active Radiation (fapar), Brightness Temperature, SIGMA NAUGHT, Land Use/Land Cover Classification, Land Surface Temperature, Emissivity
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