Skip to main content

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
Geographic Region
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: 2025-12-14

Documents

Variables

Variables are a set of physical properties whose values determine the characteristics or behavior of something. For example, temperature and pressure are variables of the atmosphere. Parameters and variables can be used interchangeably. Variable level attributes provide individual information for each variable.

The Name in this table is the variable name. Fill value indicates missing or undefined data points in a variable. Valid range is the range of values the variable can store. Scale factor is used to increase or decrease the size of an object and can be used to correct for distortion. For questions on a specific variable, please use the Earthdata Forum.

Name Description Units Data Type Fill Value Valid Range Scale Factor
latitude latitude degrees_north float N/A N/A 1
longitude longitude degrees_east float N/A N/A 1
SIGMA_daily units represent soil moisture content as a fractional volume (cm3 cm-3) 1 float -9999 N/A 1
SIGMA_subdaily units represent soil moisture content as a fractional volume (cm3 cm-3) 1 float -9999 N/A 1
SM_daily units represent soil moisture content as a fractional volume (cm3 cm-3) 1 float -9999 N/A 1
SM_subdaily units represent soil moisture content as a fractional volume (cm3 cm-3) 1 float -9999 N/A 1
time time days since 1970-01-01 00:00:00 UTC float N/A N/A 1
timeintervals start and stop time for the sub-daily time periods hours float -9999 N/A 1
You're viewing 8 of 8