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Description

This dataset contains the third release, Version 1.2, of the CYGNSS Level 2 Ocean Surface Heat Flux Climate Data Record (CDR), which provides the time-tagged and geolocated ocean surface heat flux parameters with 25x25 kilometer footprint resolution with 6-7 day latency from the Delay Doppler Mapping Instrument (DDMI) aboard the Cyclone Global Navigation Satellite System (CYGNSS) constellation. CYGNSS is a NASA Earth System Science Pathfinder Mission designed to collect the first frequent space-based measurements of surface wind speeds in the inner core of tropical cyclones. The Coupled Ocean-Atmosphere Response Experiment (COARE) version 3.5 algorithm combines CYGNSS L2 CDR v1.2 ocean surface wind speed estimates with the auxiliary parameters provided by the European Centre for Medium-Range Weather Forecasts Reanalysis Version 5 (ERA5) to produce latent and sensible heat fluxes and their respective transfer coefficients. More information on how the data is produced and validated can be found in the dataset user guide (see Documentation tab). More information on the CYGNSS mission, spacecraft, instrumentation and related datasets is available here: https://podaac.jpl.nasa.gov/CYGNSS . Additional information on the CYGNSS L2 CDR v1.2 wind speed dataset is available here: https://doi.org/10.5067/CYGNS-L2C12 .

Product Summary

Platforms
CYGNSS
Instruments
DDMI
Spatial Extent

N: 38 S: -38 E: 180 W: -180

Spatial Resolution
25000 Meters x 25000 Meters
Geographic Region
GLOBAL ,
TROPICS
Coordinate System
CARTESIAN
Granule Spatial Representation
CARTESIAN
Temporal Extent
2018-08-01
Data Partner
Physical Oceanography Distributed Active Archive Center, Jet Propulsion Laboratory, NASA (NASA/JPL/PODAAC) ,
Cyclone Global Navigation Satellite System Mission, NASA Earth Science System Pathfinder, University of Michigan (NASA/ESSP/UMICH/CYGNSS)
Concept ID
C2646932894-POCLOUD
Data State
COMPLETE
Number of Files/Granules
2678
Processing Level
2
Published
Updated
Science Keywords
Heat Flux ,
Sea Surface Temperature

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

NASA/JPL. (2023). CYGNSS Level 2 Surface Flux Climate Data Record Version 1.2 [Data set]. NASA Physical Oceanography Distributed Active Archive Center. https://doi.org/10.5067/CYGNS-C2H12 Date Accessed: 2025-12-13

Documents

USER'S GUIDE

ALGORITHM THEORETICAL BASIS DOCUMENT (ATBD)

ANOMALIES

DATA CITATION GUIDELINES

PUBLICATIONS

GENERAL DOCUMENTATION

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
air_density Air density at surface received from the ERA5 variable 'p140209' kg m-3 float -9999 N/A 1
air_temperature 2 meter air temperature received from the ERA5 variable 't2m' K float -9999 N/A 1
antenna The CYGNSS nadir antenna that received the reflected GPS signal associated with the DDMs utilized to derive wind_speed. 0 = none 1 = zenith (never used) 2 = nadir_starboard 3 = nadir_port 1 byte -99 N/A 1
boundry_layer_height Boundry layer height received from the ERA5 variable 'blh' m float -9999 N/A 1
cygnss_l2_sample_index A sample index for the corresponding CYGNSS L2 sample index used for deriving the heat fluxes. This can be used with 'source' to look up the CYGNSS L2 data and metadata. N/A int N/A N/A 1
dew_point_temperature 2 meter dew point temperature received from the ERA5 variable 'd2m' K float -9999 N/A 1
lat The latitude of the heat fluxes. degrees_north float -9999 N/A 1
lhf The latent heat flux estimates at each specular point using the CYGNSS Level-2 wind_speed FDS minimum variance product. W m-2 float -9999 N/A 1
lhf_uncertainty Standard deviation of the additive latent heat flux error, based on known and reported uncertainties from CYGNSS L2 FDS winds, and ERA5 temperature and humidity. Dependent on lhf, in W m-2. W m-2 float -9999 N/A 1
lhf_yslf The latent heat flux estimates at each specular point using the CYGNSS Level-2 YSLF product. W m-2 float -9999 N/A 1
lhf_yslf_uncertainty Standard deviation of the additive latent heat flux error, based on known and reported uncertainties from CYGNSS L2 YSLF winds, and ERA5 temperature and humidity. Dependent on lhf_YSLF, in W m-2. W m-2 float -9999 N/A 1
lon The longitude of the heat fluxes degrees_east float -9999 N/A 1
prn_code The PRN code of the GPS signal associated with the DDMs utilized to derive heat fluxes. Ranges from 0 to 32. 0 = reflectometry channel idle. 1 to 32 represent a PRN code. 1 byte -99 N/A 1
quality_flags Set of status flags, set to 1 if condition is true. Flag bit masks: 1 = poor_overall_quality: The logical OR of the following flags. If any one of the following flags are set then poor_overall_quality will be set: low_range_corrected_gain OR cygnss_l2_fds_fatal_flag OR low_fds_wind_speed OR low_yslf_wind_speed OR high_fds_wind_speed OR high_yslf_wind_speed OR cygnss_l2_yslf_fatal_flag 2 = spare_1, Always zero 4 = low_range_corrected_gain, Range corrected gain is less than 3 8 = ascending_satellite, satellite is on the ascending node of the orbit (subsatellite point latitude is increasing) 16 = cygnss_l2_fds_fatal_flag, CYGNSS Level-2 FDS sample flag is set to fatal 32 = low_fds_wind_speed, CYGNSS Level-2 FDS wind speed < 0 m/s 64 = low_yslf_wind_speed, CYGNSS Level-2 YSLF wind speed < 0 m/s 128 = high_fds_wind_speed, CYGNSS Level-2 FDS wind speed > 25 m/s 256 = high_yslf_wind_speed, CYGNSS Level-2 YSLF wind speed > 25 m/s 512 = cygnss_l2_yslf_fatal_flag, CYGNSS Level-2 YSLF sample flag is set to fatal N/A short -9999 N/A 1
sample The netCDF coordinate variable associated with the sample dimension, which enumerates the zero-justified index range of the DDM time instants contained in the file. 1 int N/A N/A 1
sample_time The mean of ddm_timestamp_utc of the DDMs that were utilized to derive the heat fluxes. Note that the DDM sampling period is not synchronized with the UTC change of second so sample_time can occur at any time relative to the UTC change of second. seconds since 2023-02-01 00:00:00.499 double N/A N/A 1
shf The sensible heat flux estimates at each specular point using the CYGNSS Level-2 wind_speed FDS minimum variance product. W m-2 float -9999 N/A 1
shf_uncertainty Standard deviation of the additive sensible heat flux error, based on known and reported uncertainties from CYGNSS L2 FDS winds, and ERA5 temperature and humidity. Dependent on shf, in W m-2. W m-2 float -9999 N/A 1
shf_yslf The sensible heat flux estimates at each specular point using the CYGNSS Level-2 YSLF product. W m-2 float -9999 N/A 1
shf_yslf_uncertainty Standard deviation of the additive sensible heat flux error, based on known and reported uncertainties from CYGNSS L2 YSLF winds, and ERA5 temperature and humidity. Dependent on shf_yslf, in W m-2. W m-2 float -9999 N/A 1
spacecraft_id The CCSDS spacecraft identifier: 0xF7 (247): CYGNSS 1 0xF9 (249): CYGNSS 2 0x2B ( 43): CYGNSS 3 0x2C ( 44): CYGNSS 4 0x2F ( 47): CYGNSS 5 0x36 ( 54): CYGNSS 6 0x37 ( 55): CYGNSS 7 0x49 ( 73): CYGNSS 8 0x00 ( 0): end to end simulator 0x0E ( 14): engineering model 0x0D ( 15): default 0xFF (255): unknown 1 short -9999 N/A 1
spacecraft_num The CYGNSS spacecraft number: Ranges from 1 through 8 and 99. 1 through 8 are on-orbit spacecraft. 99 is the CYGNSS end-to-end simulator. 1 byte -99 N/A 1
surface_pressure Surface pressure received from the ERA5 variable 'sp' Pa float -9999 N/A 1
surface_skin_temperature Surface skin temperature received from the ERA5 variable 'skt' K float -9999 N/A 1
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