CYGNSS Level 2 Climate Data Record Version 1.0

4 Publications Cited this Dataset
Citation metrics available for years (2014-2021)
Processing Level2
Start/Stop Date2017-Mar-18 to 2021-Feb-28
Short NameCYGNSS_L2_CDR_V1.0
DescriptionThis dataset contains the Version 1.0 CYGNSS Level 2 Climate 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. 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 2 months (or better) from the last recorded measurement time. The Version 1.0 CDR represents the first climate-quality release and is a collection of reanalysis products derived from the SDR v2.1 Level 1 data. Calibration accuracy and long term stability are improved relative to the SDR v2.1 using a new trackwise correction algorithm which constrains the average value of the L1 data using MERRA-2 reanalysis wind speeds. Details of the algorithm are provided in the Trackwise Corrected CDR Algorithm Theoretical Basis Document. CDR Level 2 and 3 products (ocean surface wind speed, mean square slope, and latent and sensible heat flux) are generated from the CDR L1 data using the v2.1 SDR data processing algorithms. These products also exhibit improved calibration accuracy and stability over SDR v2.1. Trackwise correction is applied to the two primary CYGNSS L1 science data products the normalized bistatic radar cross section (NBRCS) and the leading edge slope of the Doppler-integrated delay waveform (LES). The correction compensates for variations in the transmit power level of the GPS signals measured by the CYGNSS bistatic radar receivers. The SDR v2.1 L1 algorithm assumes a constant GPS transmit power and variations in it can be misinterpreted as variations in the L1 data and in subsequent L2 science data products derived from them. The GPS constellation consists of several different satellite models (a.k.a. block types) and the level of transmit power variation differs between them. The more recent Block IIF models (which account for ~37% of the GPS constellation) have significantly larger variations than the older models and, for this reason, they have been screened out and not used to produce SDR v2.1 L2 or L3 science data products. Trackwise correction eliminates the need for this screening so CDR L2 and L3 data products now include Block IIF samples. It should be noted that the trackwise correction algorithm cannot be successfully applied to all SDR v2.1 L1 data so there is also some loss of samples that were present in SDR v2.1. Overall, there is a significant increase in sampling and improvement in spatial coverage with the CDR products.
Swath Width25 km
Name: Cyclone Global Navigation Satellite System (CYGNSS)
Orbit Period: 94.0 minutes
Inclination Angle: 35.0 degrees
Name: Delay Doppler Mapping Instrument (DDMI)
Swath Width: 25.0 kilometers
Description: Spacecraft angular distance from orbital plane relative to the Equator.

ProjectCyclone Global Navigation Satellite System (CYGNSS)
Data ProviderPublisher: PO.DAAC
Creator: CYGNSS
Release Place: PO.DAAC
Release Date: 2020-May-22

Keyword(s)cygnss, ddm, ddmi, doppler, delay doppler, delay, specular point, wind, winds, wind speed, cdr, climate data record, climate, version 1.0, v1.0
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Spatial Resolution: 25000 Meters x 25000 Meters
Temporal Resolution: Hourly - < Daily
Region: GLOBAL
North Bounding Coordinate: 40 degrees
South Bounding Coordinate: -40 degrees
West Bounding Coordinate: -180 degrees
East Bounding Coordinate: 180 degrees
Time Span: 2017-Mar-18 to 2021-Feb-28
Granule Time Span: 2017-Mar-18 to 2021-Feb-28
Swath Width: 25 km
Projection Type: Satelllite native along-track
Projection Detail: Geolocation information included for each pixel
Ellipsoid: WGS 84
NameLong NameUnit
antennaReceive antenna1
averaged_l1Maximum number of time-averaged L1-samples occuring in the same second1
azimuth_angleAzimuth angledegree
ddmMaximum number of time-averaged DDMs1
ddm_averaged_l1_utilized_flagDDM Average L1 utilized flags1
ddm_channelLevel 1 DDM reflectometry channels1
ddm_lesDDM leading edge slope observables1
ddm_nbrcsDDM normalized bistatic radar cross secton observables1
ddm_num_averaged_l1Number of valid L1 samples averaged1
ddm_obs_utilized_flagDDM-utilized flags1
ddm_sample_indexLevel 1 netCDF sample indices1
ddm_sourceLevel 0 data source1
fds_les_wind_speedFully Developed Seas retrieval of wind speed from LESm s-1
fds_nbrcs_wind_speedFully Developed Sea retrieval of wind speed from NBRCSm s-1
fds_sample_flagsSample status flags for Fully Developed Seas wind speed retreval
fresnel_coeffFresnel power reflection coefficient1
incidence_angleIncidence angledegree
les_meanLES mean1
mean_square_slopeMean square slope1
mean_square_slope_uncertaintyMean square slope uncertainty1
merra2_wind_speedMERRA-2 reference wind speedm s-1
nbrcs_meanNBRCS mean1
num_ddms_utilizedNumber of DDM utilized1
prn_codeGPS PRN code1
range_corr_gainRange corrected gain1e-27 dBi meter-4
sampleSample index1
sample_flagsGeneral status flags for the sample
sample_timeSample time seconds since 2017-03-18 00:00:00.999261471
sc_altSpacecraft altitudemeter
sc_latSubsatellite point latitudedegrees_north
sc_lonSubsatellite point longitudedegrees_east
spacecraft_idCCSDS spacecraft identifier1
spacecraft_numCYGNSS spacecraft number1
sum_neg_brcs_value_used_for_nbrcs_flagsSum of negative BRCS values used for NBRCS flags1
sv_numGPS space vehicle number1
wind_speedRetrieved wind speed using Minimum Variance estimator applied to Fully Developed Seas retrievals from NBRCS and LESm s-1
wind_speed_uncertaintyUncertainty in MV FDS wind speedm s-1
yslf_les_wind_speedYoung Seas/Limited Fetch retrieval of wind speed from LESm s-1
yslf_les_wind_speed_uncertaintyUncertainty in LES YSLF wind speedm s-1
yslf_nbrcs_wind_speedYoung Seas/Limited Fetch retrieval of wind speed from NBRCSm s-1
yslf_nbrcs_wind_speed_uncertaintyUncertainty in NBRCS YSLF wind speedm s-1
yslf_sample_flagsSample status flags for Young Seas/Limited Fetch wind speed retreval
    Ruf, C., R. Atlas, P. Chang, M. Clarizia, J. Garrison, S. Gleason, S. Katzberg, Z. Jelenak, J. Johnson, S. Majumdar, A. O'Brien, D. Posselt, A. Ridley, R. Rose, V. Zavorotny (2015). New Ocean Winds Satellite Mission to Probe Hurricanes and Tropical Convection. Bull. Amer. Meteor. Soc., doi:10.1175/BAMS-D-14-00218.1.
    Ruf, C., S. Asharaf, R. Balasubramaniam, S. Gleason, T. Lang, D. McKague, D. Twigg, and D. Waliser. (2019). In-Orbit Performance of the Constellation of CYGNSS Hurricane Satellites. Bull. Amer. Meteor. Soc., 100, 2009 - 2023,
Citation is critically important for dataset documentation and discovery. Please cite the data as follows, and cite the reference papers when it is appropriate.
Citation CYGNSS. 2020. CYGNSS Level 2 Climate Data Record Version 1.0. Ver. 1.0. PO.DAAC, CA, USA. Dataset accessed [YYYY-MM-DD] at

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For more information see Data Citations and Acknowledgments.

Journal Reference Ruf, C. S., Chew, C., Lang, T., Morris, M. G., Nave, K., Ridley, A., and Balasubramaniam, R.. 2018. A New Paradigm in Earth Environmental Monitoring with the CYGNSS Small Satellite Constellation, Scientific Reports, 8.

VersionDatasetVersion DateStatus
3.2CYGNSS Level 2 Climate Data Record Version 3.22024-04-10ACTIVE2024-04-10T19:38:00.000Z
1.2CYGNSS Level 2 Climate Data Record Version 1.22022-05-19ACTIVE2022-05-19T21:14:00.000Z
1.1CYGNSS Level 2 Climate Data Record Version 1.12022-04-05ACTIVE2022-04-05T14:45:00.000Z
1.0CYGNSS Level 2 Climate Data Record Version 1.02021-10-18COMPLETE2021-10-18T18:51:00.000Z