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Description

This dataset contains the version 3.2 CYGNSS level 2 science data record which provides the time-tagged and geolocated average wind speed (m/s) and mean square slope (MSS) with 25x25 kilometer resolution from the Delay Doppler Mapping Instrument aboard the CYGNSS satellite constellation. This version supersedes Version 3.1: https://doi.org/10.5067/CYGNS-L2X31. The reported sample locations are determined by the specular points corresponding to the Delay Doppler Maps (DDMs). A subset of DDM data used in the direct processing of the average wind speed and MSS is co-located inside of the Level 2 data files. Only one netCDF data file is produced 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. <br><br>

The L2 Geophysical Model Function (GMF) that maps L1 observables to ocean surface wind speed and the Significant Wave Height (SWH) second order correction to the wind speed retrievals were rederived to be consistent with the v3.2 L1 calibration. The method used for deriving the GMF and SWH correction is the same as for v3.1. An additional swell wave correction has been added to better account for the long wave dependence at low wind speeds. The FDS and YSLF retrieval algorithms are otherwise the same as v3.1. The v3.2 L2 YSLF wind speed is now designated as an intermediate product and should not be used ‘as is’. Additional quality control filters have been added to the Level 3 gridded product derived from the L2 YSLF wind speed to detect and remove outlier L2 samples, and use of the L3 product is recommended.<br><br>
The CYGNSS is a NASA Earth System Science Pathfinder Mission that is intended to collect the first frequent space‐based measurements of surface wind speeds in the inner core of tropical cyclones. Made up of a constellation of eight micro-satellites, the observatories provide nearly gap-free Earth coverage using an orbital inclination of approximately 35° from the equator, with a mean (i.e., average) revisit time of seven hours and a median revisit time of three hours. This inclination allows CYGNSS to measure ocean surface winds between approximately 38° N and 38° S latitude. This range includes the critical latitude band for tropical cyclone formation and movement.

Product Summary

Platforms
CYGNSS
Instruments
DDMI
Spatial Extent

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

Spatial Resolution
25 Kilometers x 25 Kilometers
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
C2832196001-POCLOUD
Data State
ACTIVE
Number of Files/Granules
2841
Processing Level
2
Published
Updated
Science Keywords
Wind Direction ,
Wind Speed

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

CYGNSS. (2024). CYGNSS Level 2 Science Data Record Version 3.2 [Data set]. NASA Physical Oceanography Distributed Active Archive Center. https://doi.org/10.5067/CYGNS-L2X32 Date Accessed: 2026-05-17

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
wind_speed The average surface wind speed of the 25 x 25 km cell centered on lat and lon derived from both the NBRCS and the LES observables using the fully developed seas geophysical model function, m/s. The FDS SWH correction is applied. Multiple DDMs are utilized to derive wind_speed. The number of utilized DDMs ranges from 1 to 5. m s-1 float -9999 N/A 1 N/A
wind_speed_bias Bias of the wind speed error in the minimum variance fully developed seas wind speed (wind_speed) retrieval (dependent on the incidence angle of the specular point location, on the roll state, on the wind speed, and on the block type of the GPS transmitter), in m/s. m s-1 float -9999 N/A 1 N/A
wind_speed_uncertainty Standard deviation of the additive wind speed error in the minimum variance fully developed seas wind speed (wind_speed) retrieval (dependent on the RCG and incidence angle of the specular point location, on the wind speed, and on the block type of the GPS transmitter), in m/s. m s-1 float -9999 N/A 1 N/A
yslf_sample_flags Set of status flags, set to 1 if condition is true. Flag bit masks: 1 = fatal_composite_yslf_wind_speed, logical OR of fatal FDS and YSLF flags (fatal_neg_yslf_wind_speed OR fatal_yslf_high_wind_speed OR fatal_yslf_invalid_swh OR fatal_yslf_inc_angle OR fatal_yslf_bin_ratio) 2 = spare_11, always zero 4 = spare_12, always zero 8 = spare_13, always zero 16 = fatal_neg_yslf_wind_speed, yslf_nbrcs_high_wind_speed &lt;= 0 m/s 32 = spare_14, always zero 64 = spare_15, always zero 128 = spare_16, always zero 256 = fatal_high_yslf_wind_speed, nbrcs_mean corresponds to a YSLF wind speed &gt;= 99.9 m/s 512 = spare_17, always zero 1024 = non_fatal_ascending, satellite is on the ascending node of the orbit (subsatellite point latitude is increasing) 2048 = spare_18, always zero 4096 = spare_19, always zero 8192 = spare_20, always zeron 16384 = spare_21, always zero 32768 = spare_22, always zero 65536 = spare_23, always zero 131072 = fatal_yslf_invalid_swh, unable to lookup significant wave height correction 262144 = fatal_yslf_inc_angle, incidence angle &gt; 65 degrees. 524288 = fatal_yslf_bin_ratio, bin ratio on the nadir or zenith antenna is associated with degraded performance. 1048576 = spare_24, always zero 2097152 = spare_25, always zero N/A int -9999 N/A 1 N/A
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