Friday, September 21, 2018

The PO.DAAC is pleased to announce the public release of the Cyclone Global Navigation Satellite System (CYGNSS) Version 2.1 Science Data Record. CYGNSS is a NASA Earth System Science Pathfinder Mission collecting the first frequent space‐based measurements of ocean surface wind speeds in the inner core of tropical cyclones. Made up of a constellation of eight microsatellites, the observatories provide nearly gap-free Earth coverage using an orbital inclination of approximately 35° from the equator, with a mean (i.e., average) revisit time of seven hours and a median revisit time of three hours. This inclination allows CYGNSS to measure ocean surface winds between approximately 38° N and 38° S latitude. This coverage is targeted to observe ocean surface wind speed within the critical latitude band for global tropical cyclone formation and movement.

Version 2.1 represents the second “post-provisional” release of the CYGNSS Science Data Record generated using calibrated and validated level 1 algorithms. All data users moving forward are advised to use this latest version for fundamental science and applied research activities.

The Level 1 (L1) Science Data Record contains measurement of surface Normalized Bistatic Radar Cross Section. The Level 2 (L2) Science Data Record contains derived ocean surface wind speed and mean square slope (MSS). The Level 3 (L3) Science Data Record delivers hourly averaged wind speed and MSS provided on a 0.2x0.2 degree latitude by longitude equirectangular grid.

Each L1, L2, and L3 data file is provided in netCDF-4 format using internal compression. All data files provide data covering up to a full 24-hour UTC day. The L1 data files are specific to one of the eight CYGNSS observatories. The L2 and L3 data files consist of an aggregation of data provided from all operating observatories for a given day.

The time series for all datasets starts on 18 March 2017 and continues to the near present day with a maximum mission-specified latency of 6 days. Actual data latency may oscillate between 1 to 6 days from the last retrieved observation with lowest possible latency for the L1 data. Starting at Version 2.1, all previous data gaps due to high beta angle spacecraft maneuvering have been filled with a properly corrected calibration.

All interested data users may now gain access to the data and learn more about the updates and improvements made from Version 2.0 to Version 2.1 by visiting the following dataset information pages (specific to each processing level). The following PO.DAAC dataset description pages, supplemented by the Algorithm Theoretical Basis Documents (ATBDs), are also intended to provide more complete explanations of the various processing levels:

The Handbook, ATBDs, and other reference materials may be accessed here:

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