N: 85.044 S: -85.044 E: 180 W: -180
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Description
This data set is retired and no longer available for download. We recommend using the <a href="https://nsidc.org/data/spl4smgp/">newest version of SMAP L4 Global 3-hourly 9 km EASE-Grid Surface and Root Zone Soil Moisture Geophysical Data</a> (SPL4SMGP) data set as an alternative. </p>
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: 10.5067/9LNYIYOBNBR5)
- SMAP L4 Global 3-hourly 9 km EASE-Grid Surface and Root Zone Soil Moisture Analysis Update (SPL4SMAU, DOI: 10.5067/0D8JT6S27BS9)
- SMAP L4 Global 9 km EASE-Grid Surface and Root Zone Soil Moisture Land Model Constants (SPL4SMLM, DOI: 10.5067/5C36BVQZW28K).
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:
• The climatology to which all L4_SM precipitation forcing inputs are rescaled is now based on the climatology of the NASA IMERG-Final (Version 06B) product. Where the IMERG climatology is not available (primarily poleward of 60ºN latitude), L4_SM precipitation inputs are rescaled to the climatology of the Global Precipitation Climatology Project (GPCP) v2.3 product.
• The L4_SM precipitation forcing outside of North America and the high latitudes is now corrected to match the daily totals from the NASA IMERG (Version 06B) product. As in Version 5, precipitation corrections based on CPCU data are used in North America. The latitude band for the linear tapering of the daily precipitation corrections is now 50-60ºN/S. The IMERG-Final product, which is informed by satellite observations and monthly totals from precipitation gauges, was used during L4_SM reprocessing. Forward-processing of L4_SM uses the satellite-only IMERG-Late product, which is not informed by precipitation gauges. A change in the L4_SM Science Version ID indicates the switch from IMERG-Final to IMERG-Late inputs.
• Minor change in a parameter related to the multiplicative, lognormal perturbations of precipitation and shortwave radiation forcing to reduce minor bias between perturbed and unperturbed forcing.
The brightness temperature scaling parameters in the updated Level-4 soil moisture algorithm are based on six years of SMAP observations (April 2015 – March 2021).
Product Summary
Platforms
GEOS-5
,
Instruments
NOT APPLICABLE
,
Spatial Extent
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 2022-11-14
Temporal Resolution
3 Hour
Concept ID
C2872768284-NSIDC_CPRD
Data State
DEPRECATED
Number of Files/Granules
0
Processing Level
4
Published
Science Keywords
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.
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Citation Copied
Reichle, R., De Lannoy, G., Koster, R., Crow, W., Kimball, J., & Liu, Q. (2021). SMAP L4 Global 3-hourly 9 km EASE-Grid Surface and Root Zone Soil Moisture Geophysical Data, Version 6 [Dataset]. NASA National Snow and Ice Data Center Distributed Active Archive Center. https://doi.org/10.5067/08S1A6811J0U Date Accessed: 2026-08-18
@misc{reichle_de lannoy_koster_crow_kimball_liu_2021,
title={SMAP L4 Global 3-hourly 9 km EASE-Grid Surface and Root Zone Soil Moisture Geophysical Data, Version 6},
url={http://nsidc.org/data/SPL4SMGP/versions/6},
DOI={10.5067/08S1A6811J0U},
publisher={NASA National Snow and Ice Data Center Distributed Active Archive Center},
author={Reichle, Rolf and De Lannoy, Gabrielle and Koster, Randal and Crow, Wade and Kimball, John and Liu, Qing},
year={2021},
}
Reichle, R., De Lannoy, G., Koster, R., Crow, W., Kimball, J., & Liu, Q. (2021). SMAP L4 Global 3-hourly 9 km EASE-Grid Surface and Root Zone Soil Moisture Geophysical Data, Version 6 [Dataset]. NASA National Snow and Ice Data Center Distributed Active Archive Center. https://doi.org/10.5067/08S1A6811J0U Date Accessed: 2026-08-18
Reichle, Rolf, et al. “SMAP L4 Global 3-Hourly 9 Km EASE-Grid Surface and Root Zone Soil Moisture Geophysical Data, Version 6.” NASA National Snow and Ice Data Center Distributed Active Archive Center, 2021, https://doi.org/10.5067/08S1A6811J0U. Date Accessed: 2026-08-18
TABLE OF CONTENTS
Documents
USER'S GUIDE
ALGORITHM THEORETICAL BASIS DOCUMENT (ATBD)
DATA PRODUCT SPECIFICATION
PRODUCT QUALITY ASSESSMENT
Publications Citing This Dataset
Filters
| Title | Year Sort ascending | Author | Topic |
|---|---|---|---|
| Seasonal forecasting of local-scale soil moisture droughts with Global BROOK90: a case study of the European drought of 2018 | Vorobevskii, Ivan, Luong, Thi Thanh, Kronenberg, Rico | Leaf Characteristics, Photosynthetically Active Radiation, Leaf Area Index (LAI), Fraction Of Absorbed Photosynthetically Active Radiation (fapar), Surface Soil Moisture | |
| Characterizing Satellite Soil Moisture Drydown: A Bivariate Filtering | Sinha, Jhilam, Sharma, Ashish, Marshall, Lucy, Kim, Seokhyeon | Vegetation Index, Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), Surface Soil Moisture | |
| Deducing land-atmosphere coupling regimes from SMAP soil moisture | Makhasana, Payal R., Santanello, Joseph A., Lawston-Parker, Patricia M., Roundy, Joshua K. | Carbon Monoxide, Geopotential Height, Tropopause, Methane, Atmospheric Ozone, Surface Pressure, Outgoing Longwave Radiation, Air Temperature, Upper Air Temperature, Humidity, Total Precipitable Water, Water Vapor, Water Vapor Profiles, Cloud Liquid Water/Ice, Cloud Height, Cloud Top Pressure, Cloud Top Temperature, Cloud Vertical Distribution, Emissivity, Skin Temperature, Sea Surface Temperature, Altitude, Surface Temperature, Skin Temperature, Dew Point Temperature, Atmospheric Winds, Surface Winds, U/V Wind Components, Upper Level Winds, U/V Wind Components, Vertical Wind Velocity/Speed, Atmospheric Pressure, Sea Level Pressure, Sea Level Pressure, Specific Humidity, Atmospheric Water Vapor, Oxygen Compounds, Boundary Layer Winds, Total Ozone, Brightness Temperature, SIGMA NAUGHT, Soil Moisture/Water Content, Surface Soil Moisture | |
| A global analysis of water storage variations from remotely sensed soil moisture and daily satellite gravimetry | Blank, Daniel, Eicker, Annette, Jensen, Laura, Guntner, Andreas | Brightness Temperature, Surface Soil Moisture | |
| Mechanistic Analysis and Numerical Simulation of the 2021 Post-Fire Debris Flow in Xiangjiao Catchment, China | Ouyang, Chaojun, Xiang, Wen, An, Huicong, Wang, Fulei, Yang, Weibin, Fan, Jiying | Surface Soil Moisture | |
| Soil Moisture Estimation by Assimilating InSitu and SMAP Surface Soil Moisture Using Unscented Weighted Ensemble Kalman Filter | Fu, Xiaolei, Zhang, Yuchen, Zhong, Qi, Lu, Haishen, Ding, Yongjian, Li, Zhaoguo, Yu, Zhongbo, Jiang, Xiaolei | Leaf Area Index (LAI), Fraction Of Absorbed Photosynthetically Active Radiation (fapar), Vegetation Index, Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), Surface Soil Moisture | |
| Surface Soil Moisture Retrieval of China Using Multi-Source Data and | Yang, Zhangjian, He, Qisheng, Miao, Shuqi, Wei, Feng, Yu, Mingxiao | Surface Soil Moisture | |
| 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 | |
| IMERG Precipitation Improves the SMAP Level-4 Soil Moisture Product | Reichle, Rolf H., Liu, Qing, Ardizzone, Joseph V., Crow, Wade T., De Lannoy, Gabrielle J. M., Kimball, John S., Koster, Randal D. | Surface Soil Moisture, Soil Moisture/Water Content, Soil Temperature, Precipitation, Precipitation Amount, Precipitation Rate, Snow, Rain, Brightness Temperature | |
| Machine-learning-based nowcasting of the Vogelsberg deep-seated landslide: why predicting slow deformation is not so easy | van Natijne, Adriaan L., Bogaard, Thom A., Zieher, Thomas, Pfeiffer, Jan, Lindenbergh, Roderik C. | Precipitation, Precipitation Amount, Precipitation Rate, Snow, Rain, Surface Soil Moisture | |
| Estimating the spatial distribution of possible livestock production level using a mathematical model and the SMAP soil moisture data: The case of Botswana | Surface Soil Moisture | ||
| WaterSmart-GISA web application of a data assimilation model to support irrigation research and decision making | Zhao, Haoteng, Di, Liping, Sun, Ziheng | Leaf Area Index (LAI), Fraction Of Absorbed Photosynthetically Active Radiation (fapar), Reflectance, Land Surface Temperature, Emissivity, Surface Soil Moisture | |
| Crop-CASMA: A web geoprocessing and map service based architecture and implementation for serving soil moisture and crop vegetation condition data ... | Zhang, Chen, Yang, Zhengwei, Zhao, Haoteng, Sun, Ziheng, Di, Liping, Bindlish, Rajat, Liu, Pang-Wei, Colliander, Andreas, Mueller, Rick, Crow, Wade, Reichle, Rolf H., Bolten, John, Yueh, Simon H. | Reflectance, Surface Soil Moisture |
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