CYGNSS Level 1 Climate Data Record Version 1.0

Description

This Level 1 (L1) dataset contains the Version 1.0 Climate Data Record (CDR) of the 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. 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 2 months, depending on the availability of the MERRA wind speed reanalysis. The Version 1.0 CDR represents the first climate-quality release and is a collection of reanalysis products derived from the 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 provide in the Trackwise Corrected CDR Algorithm Theoretical Basis Document. The CDR exhibits improved calibration accuracy and stability over 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. By comparison, the v2.1 SDR 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 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 v2.1 SDR L1 data, so there is also some loss of samples that were present in v2.1. Overall, there is a significant increase in sampling and improvement in spatial coverage with the CDR products.

Resources

Name Format Description Link
21 Search results for publications that cite this dataset by its DOI. https://scholar.google.com/scholar?q=10.5067%2FCYGNS-L1C10
21 Attitude Tables Updated Monthly https://archive.podaac.earthdata.nasa.gov/podaac-ops-cumulus-docs/cygnss/open/L1/docs/att_tables/Attitude_Table_FM_4.txt
33 Deriving Surface Winds from Tropical Cyclones https://cygnss.engin.umich.edu/wp-content/uploads/sites/534/2021/06/CYGNSS_Handbook_April2016.pdf
21 CYGNSS Mission Page at University of Michigan https://cygnss.engin.umich.edu/
21 Level 1 netCDF Data Dictionary https://archive.podaac.earthdata.nasa.gov/podaac-ops-cumulus-docs/cygnss/open/L1/docs/148-0386-1_L1_v1.0_CDR_netCDF_Data_Dictionary.xlsx
21 Gleason, S., Ruf, C., Clarizia, M. P., & O'Brien, A. (2016). Calibration and Unwrapping of the Normalized Scattering Cross Section for the Cyclone Global Navigation Satellite System (CYGNSS). IEEE Trans. Geosci. Remote Sens., https://doi.org/10.1109/TGRS.2015.2502245. https://doi.org/10.1109/TGRS.2015.2502245
21 Data Use and Citation Policy https://podaac.jpl.nasa.gov/CitingPODAAC
21 HTTPS endpoint for data browse and download https://cmr.earthdata.nasa.gov/virtual-directory/collections/C1996881862-POCLOUD/
21 Browse granule search results in Earthdata Search https://search.earthdata.nasa.gov/search/granules?p=C1996881862-POCLOUD
21 Attitude Tables Updated Monthly https://archive.podaac.earthdata.nasa.gov/podaac-ops-cumulus-docs/cygnss/open/L1/docs/att_tables/Attitude_Table_FM_1.txt
21 Attitude Tables Updated Monthly https://archive.podaac.earthdata.nasa.gov/podaac-ops-cumulus-docs/cygnss/open/L1/docs/att_tables/Attitude_Table_FM_2.txt
21 Attitude Tables Updated Monthly https://archive.podaac.earthdata.nasa.gov/podaac-ops-cumulus-docs/cygnss/open/L1/docs/att_tables/Attitude_Table_FM_3.txt
21 Attitude Tables Updated Monthly https://archive.podaac.earthdata.nasa.gov/podaac-ops-cumulus-docs/cygnss/open/L1/docs/att_tables/Attitude_Table_FM_7.txt
21 Generic data readers https://github.com/podaac/data-readers
21 CYGNSS Handbook https://doi.org/10.3998/mpub.12741920
22 Thumbnail https://podaac.jpl.nasa.gov/Podaac/thumbnails/CYGNSS_L1_CDR_V1.0.jpg
21 Google Sheet Log of Anomalous CYGNSS Sampling Events https://docs.google.com/spreadsheets/d/1AFAZanVGDApLSnJQAAdPfOKoJQs0jnB8ZvIuD1Z5mAc/edit#gid=0
21 Forum Post Capturing Changes to CYGNSS Sampling Rate https://podaac.jpl.nasa.gov/forum/viewtopic.php?f=16&t=1261
33 Algorithm Theoretical Basis Document (ATBD) for Level 1B DDM Calibration, S. Gleason, CYGNSS Project Document 148-0137, Rev 2, 20 Aug. 2018. https://archive.podaac.earthdata.nasa.gov/podaac-ops-cumulus-docs/cygnss/open/L1/docs/148-0137_ATBD_L1B_DDMCalibration_Rev2_Aug2018_release.pdf
21 Attitude Tables Updated Monthly https://archive.podaac.earthdata.nasa.gov/podaac-ops-cumulus-docs/cygnss/open/L1/docs/att_tables/Attitude_Table_FM_6.txt
33 Algorithm Theoretical Basis Document (ATBD) for the CYGNSS Climate Data Record (CDR) https://archive.podaac.earthdata.nasa.gov/podaac-ops-cumulus-docs/cygnss/open/L1/docs/148-0389-1_ATBD_Trackwise_Corrected_CDR.pdf
21 Attitude Tables Updated Monthly https://archive.podaac.earthdata.nasa.gov/podaac-ops-cumulus-docs/cygnss/open/L1/docs/att_tables/Attitude_Table_FM_5.txt
21 Attitude Tables Updated Monthly https://archive.podaac.earthdata.nasa.gov/podaac-ops-cumulus-docs/cygnss/open/L1/docs/att_tables/Attitude_Table_FM_8.txt
21 Ruf, C., Atlas, R., Chang, P., Clarizia, M., Garrison, J., Gleason, S., Katzberg, S., Jelenak, Z., Johnson, J., Majumdar, S., O'Brien, A., Posselt, D., Ridley, A., Rose, R., & Zavorotny, V. (2015). New Ocean Winds Satellite Mission to Probe Hurricanes and Tropical Convection. Bull. Amer. Meteor. Soc., https://doi.org/10.1175/BAMS-D-14-00218.1. https://doi.org/10.1175/BAMS-D-14-00218.1
33 Algorithm Theoretical Basis Document (ATBD) for Level 1A DDM Calibration, S. Gleason, CYGNSS Project Document 148-0136, Rev 2, 20 Aug. 2018. https://archive.podaac.earthdata.nasa.gov/podaac-ops-cumulus-docs/cygnss/open/L1/docs/148-0136_ATBD_L1A_DDMCalibration_Rev2_Aug2018_release.pdf

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  • spectral-engineering
  • radar
  • earth-science

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