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Description

Same as L2_NALT_GDR, using preliminary values for some auxiliary data. Uses Medium-accuracy (preliminary) Orbit Ephemeris (MOE). Available with latency of < 1.5 days. Discrete measurements at nadir for each half orbit, along the ground track. Available in netCDF-4 file format.
<br>This collection is a sub-collection of its parent: https://podaac.jpl.nasa.gov/dataset/SWOT_L2_NALT_IGDR_2.0

Product Summary

Platforms
SWOT
Instruments
Jason-class Altimeter ,
AMR
Spatial Extent

N: 77.6 S: -77.6 E: 180 W: -180

Geographic Region
GLOBAL
Coordinate System
CARTESIAN
Granule Spatial Representation
GEODETIC
Temporal Extent
2022-12-16
Data Partner
Jet Propulsion Laboratory, NASA (NASA/JPL) ,
Physical Oceanography Distributed Active Archive Center, Jet Propulsion Laboratory, NASA (NASA/JPL/PODAAC)
Concept ID
C2799465538-POCLOUD
Data State
SUPERSEDED
Number of Files/Granules
14967
Processing Level
2
Published
Updated
Science Keywords
Sea Surface Height ,
Significant Wave Height

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

SWOT. (2023). SWOT Level 2 Nadir Altimeter Interim Geophysical Data Record with Waveforms Version 1.0 [Data set]. NASA Physical Oceanography Distributed Active Archive Center. https://doi.org/10.5067/SWOT-NALT-IGDR-1.0 Date Accessed: 2025-12-14

Documents

Variables

Variables are a set of physical properties whose values determine the characteristics or behavior of something. For example, temperature and pressure are variables of the atmosphere. Parameters and variables can be used interchangeably. Variable level attributes provide individual information for each variable.

The Name in this table is the variable name. Fill value indicates missing or undefined data points in a variable. Valid range is the range of values the variable can store. Scale factor is used to increase or decrease the size of an object and can be used to correct for distortion. For questions on a specific variable, please use the Earthdata Forum.

Name Description Units Data Type Fill Value Valid Range Scale Factor
/data_01/altitude Altitude of satellite above the reference ellipsoid. Associated quality flag is orb_state_diode_flag for the OGDR products, orb_state_rest_flag for the IGDR and GDR products m int 2147483647 N/A 0.0001
/data_01/alt_qual Compilation of all altimeter flags except altimeter echo type : Set to default in the current issue N/A byte 127 N/A 1
/data_01/dac Sum of the high frequency fluctuations correction and of the low frequency inverted barometer correction (inv_bar_cor). See SWOT Nadir Altimeter User Handbook m short 32767 N/A 0.0001
/data_01/depth_or_elevation ocean depth/land elevation m int 2147483647 N/A 1
/data_01/geo_qual Check on validity of all geophysical fields : Set to default in the current issue N/A byte 127 N/A 1
/data_01/ice_flag See SWOT Nadir Altimeter User Handbook N/A byte 127 N/A 1
/data_01/internal_tide_hret See SWOT Nadir Altimeter User Handbook m short 32767 N/A 0.0001
/data_01/inv_bar_cor Computed at the altimeter time-tag from the interpolation of 2 meteorological fields that surround the altimeter time-tag. See SWOT Nadir Altimeter User Handbook m short 32767 N/A 0.0001
/data_01/ku/iono_cor_alt_filtered An ionospheric correction must be added (negative value) to the instrument range to correct this range measurement for ionospheric range delays of the radar pulse. See SWOT Nadir Altimeter User Handbook m short 32767 N/A 0.0001
/data_01/ku/iono_cor_alt_filtered_mle3 An ionospheric correction must be added (negative value) to the instrument range to correct this range measurement for ionospheric range delays of the radar pulse. See SWOT Nadir Altimeter User Handbook m short 32767 N/A 0.0001
/data_01/ku/range_ocean All instrumental corrections included, i.e. distance antenna-COG (/data_01/range_cor_cog), USO drift correction (/data_01/range_cor_uso), internal path correction (range_cor_internal_path), Doppler correction (range_cor_doppler), modeled instrumental errors correction (range_cor_ocean_model_instr) and system bias m int 2147483647 N/A 0.0001
/data_01/ku/range_ocean_mle3 All instrumental corrections included, i.e. distance antenna-COG (/data_01/range_cor_cog), USO drift correction (/data_01/range_cor_uso), internal path correction (range_cor_internal_path), Doppler correction (range_cor_doppler), modeled instrumental errors correction (range_cor_ocean_mle3_model_instr) and system bias m int 2147483647 N/A 0.0001
/data_01/ku/sea_state_bias A sea state bias correction must be added (negative value) to the instrument range to correct this range measurement for sea state delays of the radar pulse. This element should not be used over land. See SWOT Nadir Altimeter User Handbook m short 32767 N/A 0.0001
/data_01/ku/sea_state_bias_mle3 A sea state bias correction must be added (negative value) to the instrument range to correct this range measurement for sea state delays of the radar pulse. This element should not be used over land. See SWOT Nadir Altimeter User Handbook m short 32767 N/A 0.0001
/data_01/ku/sig0_ocean All instrumental corrections included, excepted the system bias, i.e. AGC instrumental errors correction, internal calibration correction (sig0_cor_calibration), modeled instrumental errors correction (sig0_cor_ocean_model_instr) and atmospheric attenuation (sig0_cor_atm) dB short 32767 N/A 0.01
/data_01/ku/sig0_ocean_mle3 All instrumental corrections included, excepted the system bias, i.e. AGC instrumental errors correction, internal calibration correction (sig0_cor_calibration), modeled instrumental errors correction (sig0_cor_ocean_mle3_model_instr) and atmospheric attenuation (sig0_cor_atm) dB short 32767 N/A 0.01
/data_01/ku/ssha = altitude of satellite (/data_01/altitude) - Ku band corrected altimeter range (range_ocean) - filtered altimeter ionospheric correction on Ku band (iono_cor_alt_filtered) - model dry tropospheric correction (/data_01/model_dry_tropo_cor_zero_altitude) - radiometer wet tropospheric correction (/data_01/rad_wet_tropo_cor) - sea state bias correction in Ku band (sea_state_bias) - solid earth tide height (/data_01/solid_earth_tide) - geocentric ocean tide height from FES solution (/data_01/ocean_tide_fes) - non-equilibrium long-period ocean tide height (/data_01/ocean_tide_non_eq) - geocentric pole tide height (/data_01/pole_tide) - internal tide (/data_01/internal_tide_hret) - dynamic atmospheric correction (/data_01/dac) - mean sea surface from CNES/CLS solution (/data_01/mean_sea_surface_cnescls). Set to default if the waveform classification (wvf_main_class) is not set to 1 = brown ocean, 12 = shifted brown, 13 = brown noise leading edge or 15 = linear positive_slope, or if the radiometer wet tropospheric interpolation quality flag (/data_01/rad_wet_tropo_cor_interp_qual) is set to 2 = fail m short 32767 N/A 0.001
/data_01/ku/ssha_mle3 = altitude of satellite (/data_01/altitude) - Ku band corrected altimeter range (range_ocean_mle3) - filtered altimeter ionospheric correction on Ku band (iono_cor_alt_filtered_mle3) - model dry tropospheric correction (/data_01/model_dry_tropo_cor_zero_altitude) - radiometer wet tropospheric correction (/data_01/rad_wet_tropo_cor) - sea state bias correction in Ku band (sea_state_bias_mle3) - solid earth tide height (/data_01/solid_earth_tide) - geocentric ocean tide height from FES solution (/data_01/ocean_tide_fes) - non-equilibrium long-period ocean tide height (/data_01/ocean_tide_non_eq) - geocentric pole tide height (/data_01/pole_tide) - internal tide (/data_01/internal_tide_hret) - dynamic atmospheric correction (/data_01/dac) - mean sea surface from CNES/CLS solution (/data_01/mean_sea_surface_cnescls). Set to default if the waveform classification (wvf_main_class) is not set to 1 = brown ocean, 12 = shifted brown, 13 = brown noise leading edge or 15 = linear positive_slope, or if the radiometer wet tropospheric interpolation quality flag (/data_01/rad_wet_tropo_cor_interp_qual) is set to 2 = fail m short 32767 N/A 0.001
/data_01/ku/swh_ocean All instrumental corrections included, i.e. modeled instrumental errors correction (swh_cor_ocean_model_instr) and system bias m short 32767 N/A 0.001
/data_01/ku/swh_ocean_mle3 All instrumental corrections included, i.e. modeled instrumental errors correction (swh_cor_ocean_mle3_model_instr) and system bias m short 32767 N/A 0.001
/data_01/ku/wvf_main_class Waveform classification : main class selected by classification neural network trained on shape features of the waveforms N/A byte 127 N/A 1
/data_01/latitude Positive latitude is North latitude, negative latitude is South latitude. See SWOT Nadir Altimeter User Handbook. Associated quality flag is orb_state_diode_flag for the OGDR products, orb_state_rest_flag for the IGDR and GDR products degrees_north int 2147483647 N/A 1.0E-6
/data_01/longitude East longitude relative to Greenwich meridian. See SWOT Nadir Altimeter User Handbook. Associated quality flag is orb_state_diode_flag for the OGDR products, orb_state_rest_flag for the IGDR and GDR products degrees_east int 2147483647 N/A 1.0E-6
/data_01/mean_dynamic_topography See SWOT Nadir Altimeter User Handbook m int 2147483647 N/A 0.0001
/data_01/mean_sea_surface_cnescls See SWOT Nadir Altimeter User Handbook m int 2147483647 N/A 0.0001
/data_01/meteo_map_availability_flag Possible values are: 0 meaning ’2 maps, nominal’ (six hours apart), 1 meaning ’2 maps, degraded’ (more than six hours apart), 2 meaning ’1 map, closest map used’, 3 meaning ’no valid map’ N/A byte 127 N/A 1
/data_01/model_dry_tropo_cor_zero_altitude Computed at Mean Sea Level Pressure at the altimeter time-tag from the interpolation of 2 meteorological fields that surround the altimeter time-tag. A dry tropospheric correction must be added (negative value) to the instrument range to correct this range measurement for dry tropospheric range delays of the radar pulse. See SWOT Nadir Altimeter User Handbook m short 32767 N/A 0.0001
/data_01/ocean_tide_fes Includes the equilibrium long-period ocean tide height and only the short-period part of the corresponding loading tide. 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
/data_01/pole_tide See SWOT Nadir Altimeter User Handbook m short 32767 N/A 0.0001
/data_01/rad_cloud_liquid_water Should not be used over land kg/m^2 short 32767 N/A 0.01
/data_01/rad_qual Compilation of all radiometer flags except radiometer surface type : Set to default in the current issue N/A byte 127 N/A 1
/data_01/rad_side_1_rain_flag See SWOT Nadir Altimeter User Handbook N/A byte 127 N/A 1
/data_01/rad_side_1_sea_ice_flag See SWOT Nadir Altimeter User Handbook N/A byte 127 N/A 1
/data_01/rad_side_1_surface_type_flag radiometer surface type from first radiometer N/A byte 127 N/A 1
/data_01/rad_side_2_rain_flag See SWOT Nadir Altimeter User Handbook N/A byte 127 N/A 1
/data_01/rad_side_2_sea_ice_flag See SWOT Nadir Altimeter User Handbook N/A byte 127 N/A 1
/data_01/rad_side_2_surface_type_flag radiometer surface type from second radiometer N/A byte 127 N/A 1
/data_01/rad_water_vapor Should not be used over land kg/m^2 short 32767 N/A 0.1
/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
/data_01/rad_wet_tropo_cor_interp_qual See SWOT Nadir Altimeter User Handbook N/A byte 127 N/A 1
/data_01/rain_flag See SWOT Nadir Altimeter User Handbook N/A byte 127 N/A 1
/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
/data_01/surface_classification_flag Computed from a mask built with MODIS and GlobCover data N/A byte 127 N/A 1
/data_01/time Time of measurement in seconds in the UTC time scale since 1 Jan 2000 00:00:00 UTC. [tai_utc_difference] is the difference between TAI and UTC reference time (seconds) for the first measurement of the data set. If a leap second occurs within the data set, the attribute [leap_second] is set to the UTC time at which the leap second occurs seconds since 2000-01-01 00:00:00.0 double N/A N/A 1
/data_01/time_tai Time of measurement in seconds in the TAI time scale since 1 Jan 2000 00:00:00 TAI. This time scale contains no leap seconds. The difference (in seconds) with time in UTC is given by the attribute [time:tai_utc_difference] seconds since 2000-01-01 00:00:00.0 double 1.844674407371E+19 N/A 1
/data_01/wind_speed_alt Should not be used over land. See SWOT Nadir Altimeter User Handbook. A calibration bias of +0.06 dB has been added to the Ku band backscatter coefficient (/data_01/ku/sig0_ocean) before computing the wind speed m/s short 32767 N/A 0.01
/data_01/wind_speed_alt_mle3 Should not be used over land. See SWOT Nadir Altimeter User Handbook. A calibration bias of +0.109 dB has been added to the Ku band backscatter coefficient (/data_01/ku/sig0_ocean_mle3) before computing the wind speed m/s short 32767 N/A 0.01
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