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Description

The CYGNSS Level 3 Soil Moisture Product provides volumetric water content estimates for soils between 0-5 cm depth at a 6-hour discretization for most of the subtropics. The data were produced by CYGNSS investigators at the University Corporation for Atmospheric Research (UCAR) and the University Colorado at Boulder (CU), and derive from version 2.1 of the CYGNSS L1 SDR. The soil moisture algorithm uses collocated soil moisture retrievals from SMAP to calibrate CYGNSS observations from the same day. For a given location, a linear relationship between the SMAP soil moisture and CYGNSS reflectivity is determined and used to transform the CYGNSS observations into soil moisture. The data are archived in daily files in netCDF-4 format. Two soil moisture variables report the volumetric water content in units of cm3/cm3. The variable SM_subdaily includes up to four soil moisture estimates per day. Another variable SM_daily provides a daily average. The time series covers the period from March 2017 to present.

Product Summary

Platforms
CYGNSS
Instruments
DDMI
Spatial Extent

N: 38 S: -38 E: 164 W: -135

Spatial Resolution
0.37 Decimal Degrees x 0.3 Decimal Degrees
Location
GLOBAL ,
TROPICS
Coordinate System
CARTESIAN
Granule Spatial Representation
CARTESIAN
Temporal Extent
2017-03-18
Data Partner
Physical Oceanography Distributed Active Archive Center, Jet Propulsion Laboratory, NASA (NASA/JPL/PODAAC) ,
COSMIC Data Analysis and Archive Center, Constellation Observing System for Meteorology, Ionosphere and Climate, University Corporation for Atmospheric Research (UCAR/COSMIC/CDAAC)
Concept ID
C2205122332-POCLOUD
Data State
ACTIVE
Number of Files/Granules
2660
Processing Level
3
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

Chew, C., & Small, E. (2020). UCAR-CU CYGNSS Level 3 Soil Moisture Version 1.0 [Data set]. NASA Physical Oceanography Distributed Active Archive Center. https://doi.org/10.5067/CYGNU-L3SM1 Date Accessed: 2026-04-20

Documents

Variables

The table below lists the variables contained within a single granule for this dataset. Variables often contain observed or derived geophysical measurements collected from a variety of sources, including remote sensing instruments on satellite and airborne platforms, field campaigns, in situ measurements, and model outputs. The terms variable, parameter, scientific data set, layer, and band have been used across NASA’s Earth science disciplines; however, variable is the designated nomenclature in NASA’s Common Metadata Repository (CMR). Variable metadata attributes such as Name, Description, Units, Data Type, Fill Value, Valid Range, and Scale Factor allow users to efficiently process and analyze the data. The full range of attributes may not be applicable to all variables. Additional information on variable attributes is typically available in the data, user guide, and/or other product documentation.

For questions on a specific variable, please use the Earthdata Forum.

Name Description Units Data Type Fill Value Valid Range Scale Factor Offset
latitude latitude degrees_north float N/A N/A 1 N/A
longitude longitude degrees_east float N/A N/A 1 N/A
SIGMA_daily units represent soil moisture content as a fractional volume (cm3 cm-3) 1 float -9999 N/A 1 N/A
SIGMA_subdaily units represent soil moisture content as a fractional volume (cm3 cm-3) 1 float -9999 N/A 1 N/A
SM_daily units represent soil moisture content as a fractional volume (cm3 cm-3) 1 float -9999 N/A 1 N/A
SM_subdaily units represent soil moisture content as a fractional volume (cm3 cm-3) 1 float -9999 N/A 1 N/A
time time days since 1970-01-01 00:00:00 UTC float N/A N/A 1 N/A
timeintervals start and stop time for the sub-daily time periods hours float -9999 N/A 1 N/A
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