CYGNSS Level 1 Science Data Record Version 3.1(CYGNSS_L1_V3.1)
|Start/Stop Date||2018-Aug-01 to Present|
|Description||This Level 1 (L1) dataset contains the Version 3.1 geo-located Delay Doppler Maps (DDMs) calibrated into Power Received (Watts) and Bistatic Radar Cross Section (BRCS) expressed in units of m2 from the Delay Doppler Mapping Instrument aboard the CYGNSS satellite constellation. This version supersedes Version 3.0; https://doi.org/10.5067/CYGNS-L1X30. Other useful scientific and engineering measurement parameters include the DDM of Normalized Bistatic Radar Cross Section (NBRCS), the Delay Doppler Map Average (DDMA) of the NBRCS near the specular reflection point, and the Leading Edge Slope (LES) of the integrated delay waveform. The L1 dataset contains a number of other engineering and science measurement parameters, including sets of quality flags/indicators, error estimates, and bias estimates as well as a variety of orbital, spacecraft/sensor health, timekeeping, and geolocation parameters. At most, 8 netCDF data files (each file corresponding to a unique spacecraft in the CYGNSS constellation) are provided each day; under nominal conditions, there are typically 6-8 spacecraft retrieving data each day, but this can be maximized to 8 spacecraft under special circumstances in which higher than normal retrieval frequency is needed (i.e., during tropical storms and or hurricanes). Latency is approximately 6 days (or better) from the last recorded measurement time. Here is a summary of improvements the calibration and processing changes to the Version 3.1 data: The CYGNSS science antenna gain patterns have been adjusted to improve the accuracy of the ocean surface scattering cross section (a.k.a. the NBRCS) calibration. They are adjusted so that the annual average observed NBRCS matches the model-predicted average as derived from Wavewatch-3 estimates of the surface roughness with the appropriate spectral tail extension added to the roughness spectrum. The adjustment is made independently at each position in the science antenna pattern. A correction for coarse quantization effects by the on-board digital processor has also been added. This reduces the effects of radio frequency interference, which appeared as calibration biases in the v3.0 L1 NBRCS and retrieval biases in the v3.0 L2 wind speed that were persistent at certain locations.|
|Measurement||SPECTRAL/ENGINEERING > RADAR > RADAR CROSS-SECTION|
SPECTRAL/ENGINEERING > RADAR > RADAR REFLECTIVITY
|Swath Width||25 km|
Name: Cyclone Global Navigation Satellite System (CYGNSS)
Inclination Angle: 35.0 degrees
Orbit Period: 94.0 minutes
Name: Delay Doppler Mapping Instrument (DDMI)
Swath Width: 25.0 kilometers
Description: Spacecraft angular distance from orbital plane relative to the Equator.
|Project||Cyclone Global Navigation Satellite System (CYGNSS)|
|Data Provider||Publisher: PO.DAAC|
Release Place: PO.DAAC
Release Date: 2021-Dec-17
|Keyword(s)||cygnss, ddm, ddmi, ddma, doppler, delay doppler, delay, specular point, waveform, les, leading edge slope, bistatic, bi-static, radar, brcs, sigma0, sigma-0, sigma naught, sigma-naught, nbrcs, wind, winds, wind speed, version 3.1, v3.1|
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Spatial Resolution: 25000 Meters x 25000 Meters
Temporal Resolution: Hourly - < Daily
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 PresentSwath Width: 25 km
Projection Type: Satellite native along-track
Projection Detail: Geolocation information included for each pixel
Ellipsoid: WGS 84
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|DATA CITATION POLICY|
|DATA PRODUCT SPECIFICATION|
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 1 Science Data Record Version 3.1. Ver. 3.1. PO.DAAC, CA, USA. Dataset accessed [YYYY-MM-DD] at https://doi.org/10.5067/CYGNS-L1X31
For more information see Data Citations and Acknowledgments.
|Journal Reference||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., Bulletin of the American Meteorological Society, 100, 10.
Gleason, S., M. M. Al-Khaldi, C. Ruf, D. S. McKague, T. Wang, A. Russel . 2021. Characterizing and Mitigating Digital Sampling Effects on the CYGNSS Level 1 Calibration, IEEE Trans. Geosci. Remote Sens. 10.1109/TGRS.2021.3120026
Pascual, D., M. P. Clarizia, C. S. Ruf . 2021. Improved CYGNSS Wind Speed Retrieval Using Significant Wave Height Correction, Remote Sensing. 10.3390/rs13214313
Wang, T., Ruf, C. S., Gleason, S., O'Brien, A. J., McKague, D. S., Block, B. P., Russel, A.. 2021. Dynamic Calibration of GPS Effective Isotropic Radiated Power for GNSS-Reflectometry Earth Remote Sensing, IEEE Trans. Geosci. Remote Sens.. https://doi.org//10.1109/TGRS.2021.3070238