CYGNSS Level 2 Ocean Surface Heat Flux Science Data Record Version 1.0

(CYGNSS_L2_SURFACE_FLUX_V1.0)
1 Publication Cited this Dataset
Citation metrics available for years (2014-2022)
Version1.0
Processing Level2
Start/Stop Date2017-Mar-18 to 2020-Sep-30
Short NameCYGNSS_L2_SURFACE_FLUX_V1.0
DescriptionThis dataset contains the Version 1.0 CYGNSS Level 2 Ocean Surface Heat Flux Science Data Record, which provides the time-tagged and geolocated ocean surface heat flux parameters with 25x25 kilometer footprint resolution from the Delay Doppler Mapping Instrument (DDMI) aboard the CYGNSS satellite constellation. The reported sample locations are determined by the specular points corresponding to the Delay Doppler Maps (DDMs). Only one netCDF-4 data file is produced each day (each file containing data from a combination of up to 8 unique CYGNSS spacecraft) with a latency of approximately 1 to 2 months from the last recorded measurement time. Version 1.0 represents the first release. The Cyclone Global Navigation Satellite System (CYGNSS), launched on 15 December 2016, is a NASA Earth System Science Pathfinder Mission that was launched with the purpose 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 CYGNSS observatories provide nearly gap-free Earth coverage with a mean (i.e., average) revisit time of seven hours and a median revisit time of three hours. The 35 degree orbital inclination allows CYGNSS to measure ocean surface winds between approximately 38 degrees North and 38 degrees South latitude using an innovative combination of all-weather performance Global Positioning System (GPS) L-band ocean surface reflectometry to penetrate the clouds and heavy precipitation. The Coupled Ocean-Atmosphere Response Experiment (COARE) algorithm is what is used in this dataset to estimate the latent and sensible heat fluxes and their respective transfer coefficients. While COARE's initial intentions were for low to moderate wind speeds, the version used for this product, COARE 3.5, has been verified with direct in situ flux measurements for wind speeds up to 25 m/s. As CYGNSS does not provide air/sea temperature, humidity, surface pressure or density, the producer of this dataset obtains these values from the NASA Modern-Era Retrospective Analysis for Research and Applications Version 2 (MERRA-2), which uses data assimilation to combine all available in situ and satellite observation data with an initial estimate of the atmospheric state, provided by a global atmospheric model. Since the MERRA-2 data is only updated on monthly intervals, this corresponding heat flux dataset is likewise updated on a monthly interval to reflect the latest data available from MERRA-2, thus accounting for measurement latency, with respect to CYGNSS observables, ranging from 1 to 2 months. The data from this release compares well with in situ buoy data, including: Kuroshio Extension Observatory (KEO), National Data Buoy Center (NDBC), Ocean Sustained Interdisciplinary Time-series Environment observation System (OceanSITES), Prediction and Research Moored Array in the Tropical Atlantic (PIRATA), Research Moored Array for African-Asian-Australian Monsoon Analysis and Prediction (RAMA), and the Tropical Atmosphere Ocean (TAO) array. As this marks only the first data release, future work is expected to provide comparisons and validation with various field campaigns (e.g., PISTON, CAMP2Ex) as well as more buoy data, especially at higher flux estimates.
DOI10.5067/CYGNS-L2H10
MeasurementOCEANS > OCEAN HEAT BUDGET > HEAT FLUX
OCEANS > OCEAN TEMPERATURE > SEA SURFACE TEMPERATURE
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: 2019-Aug-11
Resource: https://cygnss.engin.umich.edu/

FormatnetCDF-4
Keyword(s)cygnss, ddm, ddmi, doppler, delay doppler, delay, specular point, wind, winds, wind speed, heat flux, shf, lhf, sensible heat, latent heat, flux, fluxes, heat fluxes, version 1.0, v1.0, version 1, v1
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
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 2020-Sep-30
Granule Time Span: 2017-Mar-18 to 2020-Sep-30
Swath Width: 25 km
 
Projection
Projection Type: Satellite native along-track
Projection Detail: Geolocation information included for each pixel
Ellipsoid: WGS 84
 
NameLong NameUnit
air_densityAir density at surfacekg m-3
air_temperature10 meter air temperatureK
cygnss_l2_sample_indexCYGNSS L2 netCDF Sample Index
effective_surface_humidityEffective surface specific humiditykg kg-1
latLatitudedegrees_north
lhfLatent heat flux calculated from L2 FDS wind speedW m-2
lhf_uncertaintyLatent heat flux uncertaintyW m-2
lhf_yslfLatent heat flux calculated from YSLF NBRCS wind speed product.W m-2
lhf_yslf_uncertaintyLatent heat flux YSLF uncertaintyW m-2
lonLongitudedegrees_east
prn_codeGPS PRN code1
quality_flagsPer-sample quality flags
sampleSample index1
sample_timeSample time seconds since 2017-03-18 00:00:00.999
shfSensible heat flux calculated from L2 FDS wind speedW m-2
shf_uncertaintySensible heat flux uncertaintyW m-2
shf_yslfSensible heat flux calculated from YSLF NBRCS wind speed product.W m-2
shf_yslf_uncertaintySensible heat flux YSLF uncertaintyW m-2
spacecraft_idCCSDS spacecraft identifier1
spacecraft_numCYGNSS spacecraft number1
specific_humidity10 meter specific humiditykg kg-1
surface_pressureSurface pressurePa
surface_skin_temperatureSurface skin temperatureK
ALGORITHM THEORETICAL BASIS DOCUMENT (ATBD)
PUBLICATIONS
  • 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.
  • 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/10.1175/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/10.3390/rs11192294
    Crespo, J. A., Posselt, D. J., & Asharaf, S. (2019). CYGNSS Surface Heat Flux Product Development. Remote Sens. 2019, 11, 2294. DOI: 10.3390/rs11192294.
  • 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.
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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. 2019. CYGNSS Level 2 Ocean Surface Heat Flux Science Data Record Version 1.0. Ver. 1.0. PO.DAAC, CA, USA. Dataset accessed [YYYY-MM-DD] at https://doi.org/10.5067/CYGNS-L2H10

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For more information see Data Citations and Acknowledgments.
Journal Reference Crespo, J. A., Posselt, D. J., and Asharaf, S.. 2019. CYGNSS Surface Heat Flux Product Development, Remote Sensing, 11, 19. https://doi.org//10.3390/rs11192294
VersionDatasetVersion DateStatus
3.2CYGNSS Level 2 Ocean Surface Heat Flux Science Data Record Version 3.22024-04-10ACTIVE2024-04-10T19:48:00.000Z
2.0CYGNSS Level 2 Ocean Surface Heat Flux Science Data Record Version 2.02022-04-05COMPLETE2022-04-05T16:16:00.000Z
1.0CYGNSS Level 2 Ocean Surface Heat Flux Science Data Record Version 1.02021-08-06COMPLETE2021-08-06T22:41:00.000Z