Skip to main content

Description

This dataset contains the Version 1.2 NOAA CYGNSS Level 2 Science Wind Speed Product Version 1.2 which provides the time-tagged and geolocated average wind speed (m/s) in 25x25 kilometer grid cells along the measurement tracks from the Delay Doppler Mapping Instrument (DDMI) aboard the CYGNSS satellite constellation. This version corresponds to the second science-quality released through the PO.DAAC, as produced by NOAA/NESDIS using a specific geophysical model function (GMF version 1.0) and a track-wise debiasing algorithm as part of the wind speed retrieval process. The reported retrieval locations are determined by averaging the specular point locations falling within each 25 km grid cell. Version 1.2 includes four major updates compared to Version 1.1 ( https://doi.org/10.5067/CYGNN-22511 ), namely: 1) the inclusion of data associated to a spacecraft roll angle exceeding +/- 5 degrees; 2) an improved wind speed performance in the higher wind speed regime; 3) a full revision of the quality flags; 4) the inclusion of a wind speed retrieval error variable. Only one netCDF-4 data file is produced for each day (each file containing data from up to 8 unique CYGNSS spacecraft) with a latency of approximately 6 days (or better) from the last recorded measurement time. Formatting of the data variables and metadata designed to be consistent with the netCDF-4 formatting provided by the legacy CYGNSS mission Level 2 wind speed science data record (SDR).

Product Summary

Platforms
CYGNSS
Instruments
DDMI
Spatial Extent

N: 40 S: -40 E: 180 W: -180

Spatial Resolution
25000 Meters x 25000 Meters
Geographic Region
GLOBAL ,
TROPICS
Coordinate System
CARTESIAN
Granule Spatial Representation
CARTESIAN
Temporal Extent
2017-05-01
Data Partner
Physical Oceanography Distributed Active Archive Center, Jet Propulsion Laboratory, NASA (NASA/JPL/PODAAC) ,
Center for Satellite Applications and Research, NESDIS, NOAA, U.S. Department of Commerce (DOC/NOAA/NESDIS/STAR)
Concept ID
C2254232941-POCLOUD
Data State
ACTIVE
Number of Files/Granules
3112
Processing Level
2
Published
Updated
Science Keywords
Radar Cross-Section ,
Surface Winds ,
Surface Winds

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

DOC/NOAA/NESDIS/STAR. (2022). NOAA CYGNSS Level 2 Science Wind Speed 25-km Product Version 1.2 [Data set]. NASA Physical Oceanography Distributed Active Archive Center. https://doi.org/10.5067/CYGNN-22512 Date Accessed: 2025-12-13

Documents

USER'S GUIDE

READ-ME

ALGORITHM THEORETICAL BASIS DOCUMENT (ATBD)

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
antenna The CYGNSS nadir antenna that received the reflected GPS signal as associated with the DDMs utilized to derive wind speed. 0 = none, 1 = zenith (never used), 2 = nadir_starboard, 3 = nadir_port. 1 byte N/A N/A 1
azimuth_angle The mean of the specular point body frame azimuth angle of the specular points of the DDMs that were utilized to derive wind_speed. degree float -9999 N/A 1
ddm_channel A twenty five element array, one per grid cell. Contains the Level 1 NetCDF reflectometry channel of the corresponding DDM. Can be utilized together with the ddm_sample_index and spacecraft_num to look up the corresponding Level 1 DDM data and metadata. N/A int -9999 N/A 1
ddm_sample_index A twenty five element array, one per grid cell. Contains the Level 1 NetCDF sample index of the corresponding DDM. Can be utilized together with ddm_channel and spacecraft_num to look up the corresponding Level 1 DDM data and metadata. N/A int -9999 N/A 1
incidence_angle The mean of the incidence angles of the specular points of the DDMs that were utilized to derive wind_speed. degree float -9999 N/A 1
lat The mean of the specular point latitudes of the DDMs that were utilized to derive wind_speed, degrees North. degrees_north float -9999 N/A 1
lon The mean of the specular point longitudes of the DDMs that were utilized to derive wind_speed, degrees East. degrees_east float -9999 N/A 1
nbrcs_mean The mean of the normalized BRCS reported for each contiguous 25 x 25 km cell found along each track. 1 float -9999 N/A 1
nbrcs_mean_corrected The corrected mean of the normalized BRCS (i.e. using the NOAA trackwise debiasing algorithm), that were utilized to derive wind_speed. 1 float -9999 N/A 1
num_ddms_utilized The number of DDMs averaged together to produce wind_speed based on 25km gridding. N/A byte N/A N/A 1
prn_code The PRN code of the GPS signal associated with the gridded wind vector cell. Ranges from 0 to 32. 0 = reflectometry channel idle. 1 through 32 = GPS PRN codes. 1 byte N/A N/A 1
range_corr_gain The mean of the RCGs of the DDMs that were utilized to produce wind_speed. Individual RCGs are equal to the receive antenna gain in the direction of the specular point multiplied by 1e27, and divided by the square of the receiver to the specular point range, and the square of the transmitter to specular point range. 1e-27 dBi meter-4 float -9999 N/A 1
rx_gain The mean of the receive antenna gains of the specular points of the DDMs that were utilized to derive wind_speed. dBi float -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_flags Set of status flags, set to 1 if condition is true. Flag bit masks: 1 = poor_overall_quality: logical OR of poor_quality_wind_nst, poor_quality_wind_sample, 2 = asc_node: set during CYGNSS ascending node, 4 = block_IIF, 8 = block_IIR, 16 = block_IIRM, 32 = non_zero_nst: the Level 1 "nst_att_status" flag (i.e. nano star tracker) was nonzero, 64 = poor_quality_wind_nst: low confidence in the reported wind speed WHILE the star tracker flag (i.e. nst_att_status) is set. 128 = poor_quality_wind_sample: set when an unrealistic wind speed sample is detected. N/A int -9999 N/A 1
sample_time The mean of ddm_timestamp_utc of the DDMs that were utilized to derive wind_speed. seconds since 2022-01-01 00:00:02 double N/A N/A 1
sc_alt Spacecraft altitude above the WGS-84 ellipsoid. meter float -9999 N/A 1
sc_lat The mean of the subsatellite point latitudes of the DDMs that were utilized to derive wind_speed, degrees North. degrees_north float -9999 N/A 1
sc_lon The mean of the subsatellite point longitudes of the DDMs that were utilized to derive wind_speed, degrees East. degrees_east float -9999 N/A 1
sc_pitch Spacecraft pitch angle relative to the orbit frame. radian float -9999 N/A 1
sc_roll Spacecraft roll angle relative to the orbit frame. radian float -9999 N/A 1
sc_yaw Spacecraft yaw angle relative to the orbit frame. radian float -9999 N/A 1
snr The mean of Smax/Navg from the DDMs that were utilized to derive wind_speed. Here, Smax is the maximum value (in raw counts) in a single DDM bin and Navg is the average per-bin raw noise counts. dB float -9999 N/A 1
spacecraft_num The CYGNSS spacecraft number: ranges from 1 through 8. 1 byte N/A N/A 1
sv_num The GPS unique space vehicle number that transmitted prn_code. 1 int N/A N/A 1
track_id A track is a temporally contiguous series of DDMs that have the same prn_code. Each track in the file is assigned a unique track_id starting with one. track_id ranges from 1 to N, where N is the total number of tracks in the file. 1 int -9999 N/A 1
wind_speed The average surface wind speed of the 25 x 25 km cell centered on lat and lon derived from the NBRCS observables using the NOAA GMF v1.0 and the NOAA trackwise debiasing algorithm. Multiple DDMs in a 25 km x 25 km cell are utilized to derive wind_speed. m s-1 float -9999 N/A 1
wind_speed_uncertainty Uncertainty in the retrieved wind speed based on the relationship between the standard deviation of the wind speed error (i.e. CyGNSS - ECMWF) and CyGNSS retrieved wind speed. m s-1 float -9999 N/A 1
You're viewing 28 of 28