CYGNSS Level 2 Science Data Record Version 2.1

(CYGNSS_L2_V2.1)
9 Publications Cited this Dataset
Citation metrics available for years (2014-2022)
Version2.1
Processing Level2
Start/Stop Date2017-Mar-18 to Present
Short NameCYGNSS_L2_V2.1
DescriptionThis dataset contains the Version 2.1 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 2.0. 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. The Version 2.1 release represents the second science-quality release. Here is a summary of improvements that reflect the quality of the Version 2.1 data release: 1) revised Geophysical Model Functions (GMFs) for both Fully Developed Seas (FDS) and Young Seas with Limited Fetch conditions, to be consistent with the calibration changes made to the v2.1 Level 1 science data products.; 2) Revised covariance matrix between DDMA and LES versions of the FDS wind speed retrieval, used by the minimum variance estimator, resulting from changes made to the v2.1 Level 1 science data products; 3) Revised debiasing algorithm coefficients used by the FDS L2 retrieval algorithm, resulting from changes made to the v2.1 Level 2 science data products; 4) revised quality control (Q/C) flags related to the required level of consistency between DDMA and LES versions of the FDS wind speed retrieval (the errors in the two retrievals are now less correlated so larger discrepancies are allowed; if either retrieval is not available, the sample receives a fatal Q/C flag); 5) new Q/C flag related to the block type of the GPS satellite which provided the transmitted signal. Samples using block II-F signals receive a fatal Q/C flag due to the higher level of uncertainty in their radiated power; 6) revised wind speed uncertainty values as a function of RCG and wind speed, plus a new dependence of the uncertainty on GPS block type to reflect the higher uncertainty in GPS radiated power for block II-F satellites.
DOI10.5067/CYGNS-L2X21
MeasurementSPECTRAL/ENGINEERING > RADAR > RADAR CROSS-SECTION
OCEANS > OCEAN WINDS > SURFACE WINDS
OCEANS > OCEAN WINDS > SURFACE WINDS
SPECTRAL/ENGINEERING > RADAR > SIGMA NAUGHT
Swath Width25 km
Platform/Sensor
CYGNSS
Platform
Name: Cyclone Global Navigation Satellite System (CYGNSS)
Orbit Period: 94.0 minutes
Inclination Angle: 35.0 degrees
/
DDMI
SENSOR
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: 2018-Sep-21
Resource: https://cygnss.engin.umich.edu/

FormatnetCDF-4
Keyword(s)cygnss, ddm, ddmi, doppler, delay doppler, delay, specular point, wind, winds, wind speed, version 2.1, v2.1
Questions related to this dataset? Contact podaac@podaac.jpl.nasa.gov
Resolution
Spatial Resolution: 25000 Meters x 25000 Meters
Temporal Resolution: Hourly - < Daily
 
Coverage
Region: GLOBAL
Region: TROPICS
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 Present
Granule Time Span: 2017-Mar-18 to 2025-Mar-09
Swath Width: 25 km
 
Projection
Projection Type: Satellite 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-samples1
azimuth_angleAzimuth angledegree
ddmMaximum number of time-averaged DDMs1
ddm_channelLevel 1 DDM reflectometry channels1
ddm_lesDDM leading edge slope observables1
ddm_nbrcsDDM normalized bistatic radar cross secton observables1
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
latLatitudedegrees_north
les_meanLES mean1
lonLongitudedegrees_east
mean_square_slopeMean square slope1
mean_square_slope_uncertaintyMean square slope uncertainty1
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 2019-01-03 00:00:00.999261476
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
DATA CITATION GUIDELINES
PUBLICATIONS
  • https://doi.org/10.1175/BAMS-D-14-00218.1
    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.
  • https://doi.org/10.1109/JSTARS.2018.2833075
    Ruf, C., R. Balasubramaniam, 'Development of the CYGNSS Geophysical Model Function for Wind Speed', IEEE J. Sel. Topics Appl. Earth Obs. Remote Sens., doi: 10.1109/JSTARS.2018.2833075, 2018.
  • https://doi.org/10.1175/JTECH-D-20-0079.1
    Asharaf, S., Waliser, D. E., Posselt, D. J., Ruf, C. S., Zhang, C., & Putra, A. W. (2021). CYGNSS Ocean Surface Wind Validation in the Tropics, Journal of Atmospheric and Oceanic Technology, 38(4), 711-724. https://doi.org/10.1175/JTECH-D-20-0079.1
  • https://doi.org/10.1175/BAMS-D-18-0337.1
    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, https://doi.org/10.1175/BAMS-D-18-0337.1.
  • https://doi.org/10.1109/TGRS.2016.2541343
    Clarizia, M. P., and C. S. Ruf, 'Wind Speed Retrieval Algorithm for the Cyclone Global Navigation Satellite System (CYGNSS) Mission', IEEE Trans Geosci. Remote Sens., doi:10.1109/TGRS.2016.2541343, 2016.
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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. 2018. CYGNSS Level 2 Science Data Record Version 2.1. Ver. 2.1. PO.DAAC, CA, USA. Dataset accessed [YYYY-MM-DD] at https://doi.org/10.5067/CYGNS-L2X21

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For more information see Data Citations and Acknowledgments.
Journal Reference Asharaf, S., Waliser, D. E., Posselt, D. J., Ruf, C. S., Zhang, C., & Putra, A. W.. 2021. CYGNSS Ocean Surface Wind Validation in the Tropics, Journal of Atmospheric and Oceanic Technology,, 38, 4. https://doi.org/10.1175/JTECH-D-20-0079.1