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Description

This enhanced Level-3 (L3) product provides a daily composite of global and Northern Hemisphere landscape freeze/thaw conditions retrieved by the Soil Moisture Active Passive (SMAP) radiometer from 6:00 a.m. descending and 6:00 p.m. ascending half-orbit passes. This product is derived from SMAP enhanced Level-1C brightness temperatures (SPL1CTB_E). Backus-Gilbert optimal interpolation techniques are used to extract maximum information from SMAP antenna temperatures and convert them to brightness temperatures. The data are then posted to two 9 km Earth-fixed, Equal-Area Scalable Earth Grids, Version 2.0 (EASE-Grid 2.0): a global cylindrical and a Northern Hemisphere azimuthal.

Version Description

Changes to this version include: • Minor bug fix to correct the indexing of bits in the AMSER-E never-frozen never-thawed maps • An improved processing methodology was applied to the input enhanced Level-1C radiometer brightness temperatures. • The data algorithms, structure, content, or processor code are otherwise unchanged from the previous version. For the full major and minor version history, go to https://nsidc.org/data/smap/version-history

Product Summary

Platforms
SMAP
Instruments
SMAP L-BAND RADIOMETER
Spatial Extent

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

,

N: 85.044 S: 45 E: 180 W: -180

Spatial Resolution
9 Kilometers x 9 Kilometers
Spatial Reference System(s)
Multiple EPSG codes (see User Guide)
Location
GLOBAL ,
NORTHERN HEMISPHERE
Coordinate System
CARTESIAN
Granule Spatial Representation
CARTESIAN
Temporal Extent
2015-03-31 to Present
Temporal Resolution
1 Day
Concept ID
C2938664439-NSIDC_CPRD
Data State
ACTIVE
Number of Files/Granules
4100
Processing Level
3
Published
Science Keywords
Transition Direction

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

Xu, X., Dunbar, R., Derksen, C., Colliander, A., Kim, Y., & Kimball, J. (2023). SMAP Enhanced L3 Radiometer Global and Northern Hemisphere Daily 9 km EASE-Grid Freeze/Thaw State, Version 4 [Dataset]. NASA National Snow and Ice Data Center Distributed Active Archive Center. https://doi.org/10.5067/NQLCDOZJYAKX Date Accessed: 2026-09-12

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