N: 77.6 S: -77.6 E: 180 W: -180
Description
The SWOT Level 2 Nadir Altimeter Geophysical Data Record (GDR) with Waveforms dataset produced by the Surface Water and Ocean Topography (SWOT) mission provides sea surface height, significant wave height and wind speed measurements from the Poseidon-3C nadir altimeter, a Jason-class dual frequency (Ku/C) altimeter. SWOT is a joint mission between NASA and CNES that launched on December 16, 2022. It aims to measure ocean surface topography with unprecedented resolution and accuracy, as well as map inland water bodies globally. The GDR dataset consists of discrete measurements for each half orbit along the ground track with sampling resolutions of approximately 6-km and 300-m at 1Hz and 20Hz, respectively. The data were processed using restituted auxiliary data and the Precise Orbit Ephemeris (POE). The data are available with latency of < 90 days and distributed in netCDF-4 file format.
This collection is a sub-collection of its parent: https://podaac.jpl.nasa.gov/dataset/SWOT_L2_NALT_GDR_D
Product Summary
Citation
Citation is critically important for dataset documentation and discovery. This dataset is openly shared, without restriction, in accordance with the EOSDIS Data Use and Citation Guidance.
Copy Citation
Documents
USER'S GUIDE
GENERAL DOCUMENTATION
DATA CITATION GUIDELINES
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 | Offset |
|---|---|---|---|---|---|---|---|
| /data_01/ocean_tide_eq | This value has already been added to the two geocentric ocean tide height values recorded in the product (ocean_tide_got and ocean_tide_fes). The permanent tide (zero frequency) is not included in this parameter because it is included in the geoid and mean sea surface (geoid, mean_sea_surface_cnescls). See SWOT Nadir Altimeter User Handbook | m | short | 32767 | N/A | 0.0001 | N/A |
| /data_01/ocean_tide_fes | Includes the equilibrium long-period ocean tide height (ocean_tide_eq) and only the short-period part of the corresponding loading tide (load_tide_fes). The permanent tide (zero frequency) is not included in this parameter because it is included in the geoid and mean sea surface (geoid, mean_sea_surface_cnescls). To get the total geocentric tide height (FES solution), do: ocean_tide_fes + ocean_tide_non_eq. See SWOT Nadir Altimeter User Handbook | m | int | 2147483647 | N/A | 0.0001 | N/A |
| /data_01/ocean_tide_fes_interp_qual | 0 = 4 points over ocean; 1 = less than 4 points; 2 = extrapolated points | N/A | byte | 127 | N/A | 1 | N/A |
| /data_01/ocean_tide_got | Includes the corresponding loading tide (load_tide_got) and equilibrium long-period ocean tide height (ocean_tide_eq). The permanent tide (zero frequency) is not included in this parameter because it is included in the geoid and mean sea surface (geoid, mean_sea_surface_cnescls). See SWOT Nadir Altimeter User Handbook | m | int | 2147483647 | N/A | 0.0001 | N/A |
| /data_01/ocean_tide_got_interp_qual | 0 = 4 points over ocean; 1 = less than 4 points; 2 = extrapolated points | N/A | byte | 127 | N/A | 1 | N/A |
| /data_01/ocean_tide_non_eq | This parameter is computed as a correction to the parameter ocean_tide_eq; it contains the long-period ocean tide and the long-period load tide components. This value can be added to ocean_tide_eq (or ocean_tide_got, ocean_tide_fes) so that the resulting value models the total non equilibrium ocean tide height. See SWOT Nadir Altimeter User Handbook | m | short | 32767 | N/A | 0.0001 | N/A |
| /data_01/orb_state_diode_flag | 0 = Accurate orbit (0 - 5 cm radial), 1 = Good orbit (5 - 10 cm radial), 2 = Moderate orbit (10 - 15 cm radial), 4-8 = Potentially degraded orbit (> 15 cm radial), 9 = Degraded orbit (e.g., as during maneuver) | N/A | byte | 127 | N/A | 1 | N/A |
| /data_01/orb_state_rest_flag | 0 characterizes a mission operations orbit that is computed during a maneuver period, 1 stands for an adjusted mission operations orbit, 2 stands for an extrapolated mission operations orbit, 3 stands for an adjusted (preliminary/precise) orbit, 4 indicates that the (preliminary/precise) orbit is estimated during a maneuver period, 5 indicates that the (preliminary/precise) orbit is interpolated over a tracking data gap, 6 means that the (preliminary/precise) orbit is extrapolated for a duration less than 1 day, 7 means that the (preliminary/precise) orbit is extrapolated for a duration that ranges from 1 day to 2 days, 8 means that the (preliminary/precise) orbit is extrapolated for a duration larger than 2 days, or that the orbit is extrapolated just after a maneuver, 9 stands for the DORIS DIODE navigator orbit. The nominal value is 3 | N/A | byte | 127 | N/A | 1 | N/A |
| /data_01/pole_tide | See SWOT Nadir Altimeter User Handbook | m | short | 32767 | N/A | 0.0001 | N/A |
| /data_01/rad_cloud_liquid_water | Should not be used over land | kg/m^2 | short | 32767 | N/A | 0.01 | N/A |
| /data_01/rad_side_1_distance_to_land | Shortest distance between nadir sub-satellite point and land | m | int | 2147483647 | N/A | 1 | N/A |
| /data_01/rad_side_1_land_frac_187 | ratio between 0 and 1 | 1 | short | 32767 | N/A | 0.01 | N/A |
| /data_01/rad_side_1_land_frac_238 | ratio between 0 and 1 | 1 | short | 32767 | N/A | 0.01 | N/A |
| /data_01/rad_side_1_land_frac_340 | ratio between 0 and 1 | 1 | short | 32767 | N/A | 0.01 | N/A |
| /data_01/rad_side_1_rain_flag | See SWOT Nadir Altimeter User Handbook | N/A | byte | 127 | N/A | 1 | N/A |
| /data_01/rad_side_1_sea_ice_flag | See SWOT Nadir Altimeter User Handbook | N/A | byte | 127 | N/A | 1 | N/A |
| /data_01/rad_side_1_surface_type_flag | radiometer surface type from first radiometer | N/A | byte | 127 | N/A | 1 | N/A |
| /data_01/rad_side_2_distance_to_land | Shortest distance between nadir sub-satellite point and land | m | int | 2147483647 | N/A | 1 | N/A |
| /data_01/rad_side_2_land_frac_187 | ratio between 0 and 1 | 1 | short | 32767 | N/A | 0.01 | N/A |
| /data_01/rad_side_2_land_frac_238 | ratio between 0 and 1 | 1 | short | 32767 | N/A | 0.01 | N/A |
| /data_01/rad_side_2_land_frac_340 | ratio between 0 and 1 | 1 | short | 32767 | N/A | 0.01 | N/A |
| /data_01/rad_side_2_rain_flag | See SWOT Nadir Altimeter User Handbook | N/A | byte | 127 | N/A | 1 | N/A |
| /data_01/rad_side_2_sea_ice_flag | See SWOT Nadir Altimeter User Handbook | N/A | byte | 127 | N/A | 1 | N/A |
| /data_01/rad_side_2_surface_type_flag | radiometer surface type from second radiometer | N/A | byte | 127 | N/A | 1 | N/A |
| /data_01/rad_ta_187 | 18.7 GHz antenna temperature | K | short | 32767 | N/A | 0.01 | N/A |
| /data_01/rad_ta_238 | 23.8 GHz antenna temperature | K | short | 32767 | N/A | 0.01 | N/A |
| /data_01/rad_ta_340 | 34 GHz antenna temperature | K | short | 32767 | N/A | 0.01 | N/A |
| /data_01/rad_tb_187 | Brightness temperatures are along-track averaged | K | int | 2147483647 | N/A | 0.01 | N/A |
| /data_01/rad_tb_187_qual | quality flag for 1 Hz radiometer data: 18.7 GHz brightness temperature | N/A | byte | 127 | N/A | 1 | N/A |
| /data_01/rad_tb_238 | Brightness temperatures are along-track averaged | K | int | 2147483647 | N/A | 0.01 | N/A |
| /data_01/rad_tb_238_qual | quality flag for 1 Hz radiometer data: 23.8 GHz brightness temperature | N/A | byte | 127 | N/A | 1 | N/A |
| /data_01/rad_tb_340 | Brightness temperatures are along-track averaged | K | int | 2147483647 | N/A | 0.01 | N/A |
| /data_01/rad_tb_340_qual | quality flag for 1 Hz radiometer data: 34 GHz brightness temperature | N/A | byte | 127 | N/A | 1 | N/A |
| /data_01/rad_tmb_187 | Brightness temperatures are unsmoothed (along-track averaging has not been performed on the brightness temperatures) | K | int | 2147483647 | N/A | 0.01 | N/A |
| /data_01/rad_tmb_238 | Brightness temperatures are unsmoothed (along-track averaging has not been performed on the brightness temperatures) | K | int | 2147483647 | N/A | 0.01 | N/A |
| /data_01/rad_tmb_340 | Brightness temperatures are unsmoothed (along-track averaging has not been performed on the brightness temperatures) | K | int | 2147483647 | N/A | 0.01 | N/A |
| /data_01/rad_water_vapor | Should not be used over land | kg/m^2 | short | 32767 | N/A | 0.1 | N/A |
| /data_01/rad_wet_tropo_cor | A wet tropospheric correction must be added (negative value) to the instrument range to correct this range measurement for wet tropospheric range delays of the radar pulse | m | short | 32767 | N/A | 0.0001 | N/A |
| /data_01/rad_wet_tropo_cor_interp_qual | See SWOT Nadir Altimeter User Handbook | N/A | byte | 127 | N/A | 1 | N/A |
| /data_01/rad_wind_speed | Should not be used over land. See SWOT Nadir Altimeter User Handbook | m/s | short | 32767 | N/A | 0.01 | N/A |
| /data_01/rain_flag | See SWOT Nadir Altimeter User Handbook | N/A | byte | 127 | N/A | 1 | N/A |
| /data_01/rain_rate | See SWOT Nadir Altimeter User Handbook | mm/h | short | 32767 | N/A | 0.01 | N/A |
| /data_01/range_cor_cog | Distance antenna-COG correction on altimeter range | m | short | 32767 | N/A | 0.0001 | N/A |
| /data_01/range_cor_uso | Correction of the USO frequency drift on the altimeter range | m | int | 2147483647 | N/A | 0.0001 | N/A |
| /data_01/sea_ice_concentration | percentage between 0 and 100 | 1 | short | 32767 | N/A | 0.01 | N/A |
| /data_01/sea_ice_concentration_interp_qual | 0 = interpolation from 4 points; 1 = interpolation from less than 4 points | N/A | byte | 127 | N/A | 1 | N/A |
| /data_01/sig0_cor_atm_source | Flag indicating whether the radiometer data or the climatological values from meteorological model (ECMWF backup solution) have been used to compute the atmospheric sigma0 correction | N/A | byte | 127 | N/A | 1 | N/A |
| /data_01/solid_earth_tide | Calculated using Cartwright and Tayler tables and consisting of the second and third degree constituents. The permanent tide (zero frequency) is not included. See SWOT Nadir Altimeter User Handbook | m | short | 32767 | N/A | 0.0001 | N/A |
| /data_01/sst | sea surface temperature | K | short | 32767 | N/A | 0.01 | N/A |
| /data_01/surface_classification_flag | Computed from a mask built with MODIS and GlobCover data | N/A | byte | 127 | N/A | 1 | N/A |