CYGNSS Level 3 Climate Data Record Version 1.1

Processing Level3
Start/Stop Date2018-Aug-01 to Present
Short NameCYGNSS_L3_CDR_V1.1
DescriptionThis dataset contains the Version 1.1 CYGNSS Level 3 Climate Data Record which provides the average wind speed and mean square slope (MSS) on a 0.2x0.2 degree latitude by longitude equirectangular grid obtained from the Delay Doppler Mapping Instrument aboard the CYGNSS satellite constellation. The Level 2 Delay Doppler Map (DDM) data are used in the direct processing of the average wind speed and MSS data that are binned on the Level 3 grid. 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. A single netCDF-4 data file is produced for each day of operation with an approximate 1 to 2 month latency. The reported sample locations are determined by the specular points corresponding to the Delay Doppler Maps (DDMs). The Version 1.1 CDR is a collection of reanalysis products derived from the SDR v3.0 Level 1 data ( ). Calibration accuracy and long term stability are improved relative to SDR v3.0 ( ) using the same trackwise correction algorithm as was used by CDR v1.0 ( ), which was derived from SDR v2.1 Level 1 data ( ). 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 v3.0 SDR data processing algorithms. These products also exhibit improved calibration accuracy and stability over SDR v3.0. 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 small errors in the Level 1 calibration, due e.g. to uncertainties in the GPS transmitting antenna gain patterns and the CYGNSS receiving antenna gain patterns. CDR v1.1 does not include a Young Seas with Limited Fetch (YSLF) wind speed product and investigators requiring wind speed measurements in and near the inner core of tropical cyclones should use the SDR v3.0 YSLF wind speed product. A YSLF wind speed product is omitted because the trackwise correction algorithm, which constrains the average value of the L1 data using MERRA-2 reanalysis wind speeds, is inherently biased toward fully developed sea state conditions. The constraint improves wind speed retrieval performance in fully developed seas but produces underestimates in YSLF conditions. It should also be noted that the trackwise correction algorithm cannot be successfully applied to all SDR v3.0 L1 data so there is also some loss of samples that were present in SDR v3.0.
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: 2021-Feb-05

Keyword(s)cygnss, ddm, ddmi, doppler, delay doppler, delay, specular point, wind, winds, wind speed, cdr, climate data record, climate, version 1.1, v1.1
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Spatial Resolution: 0.2 degrees (Latitude) x 0.2 degrees (Longitude)
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: 2018-Aug-01 to Present
Granule Time Span: 2018-Aug-01 to 2022-Feb-28
Projection Type: Cylindrical Lat-Lon
Projection Detail: Geolocation information included for each pixel
Ellipsoid: WGS 84
    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,
    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.
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. 2021. CYGNSS Level 3 Climate Data Record Version 1.1. Ver. 1.1. 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
1.1CYGNSS Level 3 Climate Data Record Version 1.12020-12-16ACTIVE2020-12-16T21:11:14.963Z
1.0CYGNSS Level 3 Climate Data Record Version 1.02019-12-09COMPLETE2019-12-09T20:36:09.448Z