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Description

The SWOT Level 2 KaRIn Low Rate Sea Surface Height Data Product from the Surface Water Ocean Topography (SWOT) mission provides global sea surface height and significant wave height observations derived from low rate (LR) measurements from the Ka-band Radar Interferometer (KaRIn). SWOT launched on December 16, 2022 from Vandenberg Air Force Base in California into a 1-day repeat orbit for the "calibration" or "fast-sampling" phase of the mission, which completed in early July 2023. After the calibration phase, SWOT entered a 21-day repeat orbit in August 2023 to start the "science" phase of the mission, which is expected to continue through 2025. <br>
The L2 sea surface height data product is distributed in one netCDF-4 file per pass (half-orbit) covering the full KaRIn swath width, which spans 10-60km on each side of the nadir track. Sea surface height, sea surface height anomaly, wind speed, significant waveheight, and related parameters are provided on a geographically fixed, swath-aligned 2x2 km2 grid (Basic, Expert, Windwave). The sea surface height data are also provided on a finer 250x250 m2 "native" grid with minimal smoothing applied (Unsmoothed).<br>
Please note that this collection contains SWOT Version C science data products. <br>
This dataset is the parent collection to the following sub-collections: <br>
https://podaac.jpl.nasa.gov/dataset/SWOT_L2_LR_SSH_Basic_2.0 <br>
https://podaac.jpl.nasa.gov/dataset/SWOT_L2_LR_SSH_WindWave_2.0 <br>
https://podaac.jpl.nasa.gov/dataset/SWOT_L2_LR_SSH_Expert_2.0 <br>
https://podaac.jpl.nasa.gov/dataset/SWOT_L2_LR_SSH_Unsmoothed_2.0 <br>

Product Summary

Platforms
SWOT
Instruments
KaRIn ,
Jason-class Altimeter ,
AMR ,
DORIS ,
GPSP ,
LRA
Spatial Extent

N: 90 S: -90 E: 180 W: -180

Spatial Resolution
2 Kilometers x 2 Kilometers
250 Meters x 250 Meters
Location
GLOBAL
Coordinate System
CARTESIAN
Granule Spatial Representation
GEODETIC
Temporal Extent
2022-12-16
Data Partner
Physical Oceanography Distributed Active Archive Center, Jet Propulsion Laboratory, NASA (NASA/JPL/PODAAC)
Concept ID
C2799438306-POCLOUD
Data State
SUPERSEDED
Number of Files/Granules
90959
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. (2024). SWOT Level 2 KaRIn Low Rate Sea Surface Height Data Product [Data set]. NASA Physical Oceanography Distributed Active Archive Center. https://doi.org/10.5067/SWOT-SSH-2.0 Date Accessed: 2026-05-14

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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 Description Units Data Type Fill Value Valid Range Scale Factor Offset
inv_bar_cor Estimate of static effect of atmospheric pressure on sea surface height. Above average pressure lowers sea surface height. Computed by interpolating ECMWF pressure fields in space and time. The value is included in dac. To apply, add dac to ssha_karin and ssha_karin_2 and subtract inv_bar_cor. m short 32767 -2000 to 2000 0.0001 N/A
latitude Latitude of measurement [-80,80]. Positive latitude is North latitude, negative latitude is South latitude. degrees_north int 2147483647 -80000000 to 80000000 1.0E-6 N/A
latitude_avg_ssh Latitude of measurement [-80,80]. Positive latitude is North latitude, negative latitude is South latitude. This value may be biased away from a nominal grid location if some of the native, unsmoothed samples were discarded during processing. degrees_north int 2147483647 -80000000 to 80000000 1.0E-6 N/A
latitude_nadir Geodetic latitude [-80,80] (degrees north of equator) of the satellite nadir point. degrees_north int 2147483647 -80000000 to 80000000 1.0E-6 N/A
load_tide_fes Geocentric load tide height. The effect of the ocean tide loading of the Earth&#039;s crust. This value has already been added to the corresponding ocean tide height value (ocean_tide_fes). m short 32767 -2000 to 2000 0.0001 N/A
load_tide_got Geocentric load tide height. The effect of the ocean tide loading of the Earth&#039;s crust. This value has already been added to the corresponding ocean tide height value (ocean_tide_got). m short 32767 -2000 to 2000 0.0001 N/A
longitude Longitude of measurement. East longitude relative to Greenwich meridian. degrees_east int 2147483647 0 to 359999999 1.0E-6 N/A
longitude_avg_ssh Longitude of measurement. East longitude relative to Greenwich meridian. This value may be biased away from a nominal grid location if some of the native, unsmoothed samples were discarded during processing. degrees_east int 2147483647 0 to 359999999 1.0E-6 N/A
longitude_nadir Longitude (degrees east of Grenwich meridian) of the satellite nadir point. degrees_east int 2147483647 0 to 359999999 1.0E-6 N/A
mean_dynamic_topography Mean dynamic topography above the geoid. m short 32767 -30000 to 30000 0.0001 N/A
mean_dynamic_topography_uncert Accuracy of the mean dynamic topography. m ushort 65535 0 to 10000 0.0001 N/A
mean_sea_surface_cnescls Mean sea surface height above the reference ellipsoid. The value is referenced to the mean tide system, i.e. includes the permanent tide (zero frequency). m int 2147483647 -1500000 to 1500000 0.0001 N/A
mean_sea_surface_cnescls_uncert Accuracy of the mean sea surface height (mean_sea_surface_cnescls). m ushort 65535 0 to 10000 0.0001 N/A
mean_sea_surface_dtu Mean sea surface height above the reference ellipsoid. The value is referenced to the mean tide system, i.e. includes the permanent tide (zero frequency). m int 2147483647 -1500000 to 1500000 0.0001 N/A
mean_sea_surface_dtu_uncert Accuracy of the mean sea surface height (mean_sea_surface_dtu) m ushort 65535 0 to 10000 0.0001 N/A
mean_wave_direction Mean sea surface wave direction. degree ushort 65535 0 to 36000 0.01 N/A
mean_wave_period_t02 Sea surface wind wave mean period from model spectral density second moment. s short 32767 0 to 10000 0.01 N/A
model_dry_tropo_cor Equivalent vertical correction due to dry troposphere delay. The reported sea surface height, latitude and longitude are computed after adding negative media corrections to uncorrected range along slant-range paths, accounting for the differential delay between the two KaRIn antennas. The equivalent vertical correction is computed by applying obliquity factors to the slant-path correction. Adding the reported correction to the reported sea surface height results in the uncorrected sea surface height. m short 32767 -30000 to -15000 0.0001 N/A
model_wet_tropo_cor Equivalent vertical correction due to wet troposphere delay from weather model data. The reported pixel height, latitude and longitude are computed after adding negative media corrections to uncorrected range along slant-range paths, accounting for the differential delay between the two KaRIn antennas. The equivalent vertical correction is computed by applying obliquity factors to the slant-path correction. Adding the reported correction to the reported sea surface height (ssh_karin_2) results in the uncorrected sea surface height. m short 32767 -10000 0 0.0001 N/A
num_pt_avg Number of native unsmoothed, beam-combined KaRIn samples averaged. 1 ushort 65535 0 to 289 1 N/A
obp_ref_surface Height (relative to the reference ellipsoid) of the reference surface used by the KaRIn on-board processor. m int 2147483647 -15000000 to 150000000 0.0001 N/A
ocean_tide_eq Equilibrium long-period ocean tide height. This value has already been added to the corresponding ocean tide height values (ocean_tide_fes and ocean_tide_got). m short 32767 -2000 to 2000 0.0001 N/A
ocean_tide_fes Geocentric ocean tide height. Includes the sum total of the ocean tide, the corresponding load tide (load_tide_fes) and equilibrium long-period ocean tide height (ocean_tide_eq). m int 2147483647 -300000 to 300000 0.0001 N/A
ocean_tide_got Geocentric ocean tide height. Includes the sum total of the ocean tide, the corresponding load tide (load_tide_got) and equilibrium long-period ocean tide height (ocean_tide_eq). m int 2147483647 -300000 to 300000 0.0001 N/A
ocean_tide_non_eq Non-equilibrium long-period ocean tide height. This value is reported as a relative displacement with repsect to ocean_tide_eq. This value can be added to ocean_tide_eq, ocean_tide_fes, or ocean_tide_got, or subtracted from ssha_karin and ssha_karin_2, to account for the total long-period ocean tides from equilibrium and non-equilibrium contributions. m short 32767 -2000 to 2000 0.0001 N/A
orbit_alt_rate Orbital altitude rate with respect to the mean sea surface. m/s short 32767 -3500 to 3500 0.01 N/A
orbit_qual Flag indicating the quality of the reconstructed attitude and orbit ephemeris. A value of 0 indicates the reconstructed attitude and orbit ephemeris are both good. Non-zero values less than 64 indicate that the reconstructed attitude is good but there are issues that degrade the quality of the orbit ephemeris. A value of 64 indicates that the reconstructed attitude is degraded or bad. N/A ubyte 255 0 to 64 1 N/A
phase_bias_ref_surface Height (relative to the reference ellipsoid) of the reference surface used for phase bias calculation during L1B processing. m int 2147483647 -15000000 to 150000000 0.0001 N/A
polarization_karin H denotes co-polarized linear horizontal, V denotes co-polarized linear vertical. N/A string N/A N/A 1 N/A
pole_tide Geocentric pole tide height. The total of the contribution from the solid-Earth (body) pole tide height, the ocean pole tide height, and the load pole tide height (i.e., the effect of the ocean pole tide loading of the Earth&#039;s crust). m short 32767 -2000 to 2000 0.0001 N/A
rad_cloud_liquid_water Integrated cloud liquid water content from radiometer measurements. kg/m^2 short 32767 0 to 2000 0.01 N/A
rad_surface_type_flag Flag indicating the validity and type of processing applied to generate the wet troposphere correction (rad_wet_tropo_cor). A value of 0 indicates that open ocean processing is used, a value of 1 indicates coastal processing, and a value of 2 indicates that rad_wet_tropo_cor is invalid due to land contamination. N/A ubyte 255 0 to 2 1 N/A
rad_tmb_187 Main beam brightness temperature measurement at 18.7 GHz. Value is unsmoothed (along-track averaging has not been performed). K short 32767 13000 to 25000 0.01 N/A
rad_tmb_238 Main beam brightness temperature measurement at 23.8 GHz. Value is unsmoothed (along-track averaging has not been performed). K short 32767 13000 to 25000 0.01 N/A
rad_tmb_340 Main beam brightness temperature measurement at 34.0 GHz. Value is unsmoothed (along-track averaging has not been performed). K short 32767 15000 to 28000 0.01 N/A
rad_water_vapor Integrated water vapor content from radiometer measurements. kg/m^2 short 32767 0 to 15000 0.01 N/A
rad_wet_tropo_cor Equivalent vertical correction due to wet troposphere delay from radiometer measurements. The reported pixel height, latitude and longitude are computed after adding negative media corrections to uncorrected range along slant-range paths, accounting for the differential delay between the two KaRIn antennas. The equivalent vertical correction is computed by applying obliquity factors to the slant-path correction. Adding the reported correction to the reported sea surface height (ssh_karin) results in the uncorrected sea surface height. m short 32767 -10000 0 0.0001 N/A
rain_flag Flag indicates that signal is attenuated, probably from rain. N/A ubyte 255 0 to 3 1 N/A
sc_altitude Altitude of the KMSF origin. m int 2147483647 0 to 2000000000 0.0001 800000
sc_roll KMSF attitude roll angle; positive values move the +y antenna down. degrees int 2147483647 -1799999 to 1800000 0.0001 N/A
sea_state_bias_cor Sea state bias correction used to compute ssh_karin. Adding the reported correction to the reported sea surface height results in the uncorrected sea surface height. The wind_speed_karin value is used to compute this quantity. m short 32767 -6000 0 0.0001 N/A
sea_state_bias_cor_2 Sea state bias correction used to compute ssh_karin_2. Adding the reported correction to the reported sea surface height results in the uncorrected sea surface height. The wind_speed_karin_2 value is used to compute this quantity. m short 32767 -6000 0 0.0001 N/A
sig0_cor_atmos_model Atmospheric correction to sigma0 from weather model data as a linear power multiplier (not decibels). sig0_cor_atmos_model is already applied in computing sig0_karin_2. 1 float 9.96921E+36 1 to 10 1 N/A
sig0_cor_atmos_rad Atmospheric correction to sigma0 from radiometer data as a linear power multiplier (not decibels). sig0_cor_atmos_rad is already applied in computing sig0_karin. 1 float 9.96921E+36 1 to 10 1 N/A
sig0_karin Normalized radar cross section (sigma0) from KaRIn in real, linear units (not decibels). The value may be negative due to noise subtraction. The value is corrected for instrument calibration and atmospheric attenuation. Radiometer measurements provide the atmospheric attenuation (sig0_cor_atmos_rad). 1 float 9.96921E+36 -1000 to 10000000 1 N/A
sig0_karin_2 Normalized radar cross section (sigma0) from KaRIn in real, linear units (not decibels). The value may be negative due to noise subtraction. The value is corrected for instrument calibration and atmospheric attenuation. A meteorological model provides the atmospheric attenuation (sig0_cor_atmos_model). 1 float 9.96921E+36 -1000 to 10000000 1 N/A
sig0_karin_2_qual Quality flag for sigma0 from KaRIn in sig0_karin_2 variable. N/A uint 4294967295 0 to 3792125343 1 N/A
sig0_karin_qual Quality flag for sigma0 from KaRIn in sig0_karin_qual variable. N/A uint 4294967295 0 to 4060560799 1 N/A
sig0_karin_uncert 1-sigma uncertainty on sigma0 from KaRIn. 1 float 9.96921E+36 0 to 1000 1 N/A
solid_earth_tide Solid-Earth (body) tide height. The zero-frequency permanent tide component is not included. m short 32767 -10000 to 10000 0.0001 N/A
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