N: 40 S: -40 E: 180 W: -180
Description
This dataset contains the version 3.2 CYGNSS level 3 science 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 6 day latency. This version supersedes Version 3.1; https://doi.org/10.5067/CYGNS-L3X31. The reported sample locations are determined by the specular points corresponding to the Delay Doppler Maps (DDMs). <br><br>
The v3.2 L3 gridded wind speed product inherits the v3.2 L2 FDS data as input at the same temporal and spatial resolution as the Level 2 data, sampled on consistent 0.2 by 0.2 degree latitude by longitude grid cells. The L3 gridding algorithm is unchanged. Range Corrected Gain (RCG) has been added to the L3 netcdf files as a new data field. <br><br>
The CYGNSS is a NASA Earth System Science Pathfinder Mission that is intended 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 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 range includes the critical latitude band for tropical cyclone formation and movement.
Product Summary
Citation
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ALGORITHM THEORETICAL BASIS DOCUMENT (ATBD)
DATA PRODUCT SPECIFICATION
DATA CITATION GUIDELINES
GENERAL DOCUMENTATION
Variables
The table below lists the variables contained within a single granule for this dataset. Variables often contain observed or derived geophysical measurements collected from a variety of sources, including remote sensing instruments on satellite and airborne platforms, field campaigns, in situ measurements, and model outputs. The terms variable, parameter, scientific data set, layer, and band have been used across NASA’s Earth science disciplines; however, variable is the designated nomenclature in NASA’s Common Metadata Repository (CMR). Variable metadata attributes such as Name, Description, Units, Data Type, Fill Value, Valid Range, and Scale Factor allow users to efficiently process and analyze the data. The full range of attributes may not be applicable to all variables. Additional information on variable attributes is typically available in the data, user guide, and/or other product documentation.
For questions on a specific variable, please use the Earthdata Forum.
| Name Sort descending | Description | Units | Data Type | Fill Value | Valid Range | Scale Factor |
|---|---|---|---|---|---|---|
| epoch_time | Timestamp coordinate is at the center of the 1 hr bin, at 1 hour resolution referenced by the historical Epoch reference date/time. The Epoch reference date/time corresponds to the first observation time window in the CYGNSS data record after the automatic gain control was turned off. Total number of timestamps in a file corresponds to one UTC day. This value is rounded to the nearest hour since leap seconds may have occurred making the number of hours since the start of the mission not exact. | hours since 2018-08-01 00:30:00.000000000 | int | N/A | N/A | 1 |
| fds_rcg | Minimum variance estimate of the mean RCG in the bin over the spatial and temporal intervals specified by the bin's boundaries. This is done using the same samples that are used in the calculation of wind_speed. The averaging is performed with the inverse-variance that were made within the bin. | 1e-27 dBi meter-4 | float | -9999 | N/A | 1 |
| lat | Latitude coordinate at the center of the 0.2 degree bin, degrees_north, at 0.2 degree resolution. Range is -39.9 .. 39.9. | degrees_north | float | N/A | N/A | 1 |
| lon | Longitude coordinate at the center of the 0.2 degree bin, degrees_east, at 0.2 degree resolution. Range is 0.1 .. 359.9. | degrees_east | float | N/A | N/A | 1 |
| mean_square_slope | Mean MSS in the bin over the spatial and temporal intervals specified by the bin's boundaries. | 1 | float | -9999 | N/A | 1 |
| mean_square_slope_rcg | Minimum variance estimate of the mean RCG in the bin over the spatial and temporal intervals specified by the bin's boundaries. This is done using the same samples that are used in the calculation of mean_square_slope. The averaging is performed with the inverse-variance that were made within the bin. | 1e-27 dBi meter-4 | float | -9999 | N/A | 1 |
| mean_square_slope_uncertainty | Standard deviation of the error in the mean of all L2 samples of the MSS within the bin. | 1 | float | -9999 | N/A | 1 |
| num_mss_samples | The number of L2 MSS samples used to calculate mean_square_slope. | 1 | int | -99 | N/A | 1 |
| num_wind_speed_samples | The number of L2 wind speed samples used to calculate wind_speed. | 1 | int | -99 | N/A | 1 |
| time | Timestamp coordinate at the center of the 1 hr bin, at 1 hour resolution. Range is one UTC day. | hours since 2018-08-09 00:30:00.000000000 | byte | N/A | N/A | 1 |
| wind_speed | Minimum variance estimate of the mean wind speed in the bin over the spatial and temporal intervals specified by the bin's boundaries. This is done using an inverse-variance weighted average of all L2 samples of the wind speed that were made within the bin. | m s-1 | float | -9999 | N/A | 1 |
| wind_speed_uncertainty | Standard deviation of the error in the mean of all L2 samples of the wind speed within the bin. | m s-1 | float | -9999 | N/A | 1 |