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Description

The SWOT Level 2 KaRIn Low Rate Sea Surface Height Basic 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 collection is a sub-collection of its parent: https://podaac.jpl.nasa.gov/dataset/SWOT_L2_LR_SSH_2.0 It provides the "Basic" file from each L2 SSH product, which contains a limited set of variables and is aimed at the general user.

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<br>250 Meters x 250 Meters
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
C2799465428-POCLOUD
Data State
SUPERSEDED
Number of Files/Granules
19996
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: 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
ancillary_surface_classification_flag 7-state surface type classification computed from a mask built with MODIS and GlobCover data. N/A ubyte 255 0 to 6 1
distance_to_coast Approximate distance to the nearest coast point along the Earth surface. m ushort 65535 0 to 21000 1000
dynamic_ice_flag Dynamic ice flag for the location of the KaRIn measurement. N/A ubyte 255 0 to 3 1
geoid Geoid height above the reference ellipsoid with a correction to refer the value to the mean tide system, i.e. includes the permanent tide (zero frequency). m int 2147483647 -1500000 to 1500000 0.0001
heading_to_coast Approximate compass heading (0-360 degrees with respect to true north) to the nearest coast point. degrees ushort 65535 0 to 35999 0.01
height_cor_xover Height correction from crossover calibration. To apply this correction the value of height_cor_xover should be added to the value of ssh_karin, ssh_karin_2, ssha_karin, and ssha_karin_2. m int 2147483647 -100000 to 100000 0.0001
height_cor_xover_qual Flag indicating the quality of the height correction from crossover calibration. Values of 0, 1, and 2 indicate that the correction is good, suspect, and bad, respectively. N/A ubyte 255 0 to 2 1
internal_tide_hret Coherent internal ocean tide. This value is subtracted from the ssh_karin and ssh_karin_2 to compute ssha_karin and ssha_karin_2, respectively. m short 32767 -2000 to 2000 0.0001
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
longitude Longitude of measurement. East longitude relative to Greenwich meridian. degrees_east int 2147483647 0 to 359999999 1.0E-6
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
mean_sea_surface_cnescls_uncert Accuracy of the mean sea surface height (mean_sea_surface_cnescls). m ushort 65535 0 to 10000 0.0001
num_pt_avg Number of native unsmoothed, beam-combined KaRIn samples averaged. 1 ushort 65535 0 to 289 1
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
rain_flag Flag indicates that signal is attenuated, probably from rain. N/A ubyte 255 0 to 3 1
ssha_karin Sea surface height anomaly from the KaRIn measurement = ssh_karin - mean_sea_surface_cnescls - solid_earth_tide - ocean_tide_fes – internal_tide_hret - pole_tide - dac. m int 2147483647 -1000000 to 1000000 0.0001
ssha_karin_2 Sea surface height anomaly from the KaRIn measurement = ssh_karin_2 - mean_sea_surface_cnescls - solid_earth_tide - ocean_tide_fes – internal_tide_hret - pole_tide - dac. m int 2147483647 -1000000 to 1000000 0.0001
ssha_karin_2_qual Quality flag for the SSHA from KaRIn in the ssha_karin_2 variable N/A uint 4294967295 0 to 3859267071 1
ssha_karin_qual Quality flag for the SSHA from KaRIn in the ssha_karin variable. N/A uint 4294967295 0 to 4261920255 1
ssh_karin Fully corrected sea surface height measured by KaRIn. The height is relative to the reference ellipsoid defined in the global attributes. This value is computed using radiometer measurements for wet troposphere effects on the KaRIn measurement (e.g., rad_wet_tropo_cor and sea_state_bias_cor). m int 2147483647 -15000000 to 150000000 0.0001
ssh_karin_2 Fully corrected sea surface height measured by KaRIn. The height is relative to the reference ellipsoid defined in the global attributes. This value is computed using model-based estimates for wet troposphere effects on the KaRIn measurement (e.g., model_wet_tropo_cor and sea_state_bias_cor_2). m int 2147483647 -15000000 to 150000000 0.0001
ssh_karin_2_qual Quality flag for sea surface height from KaRIn in ssh_karin_2 variable. N/A uint 4294967295 0 to 3792158207 1
ssh_karin_qual Quality flag for sea surface height from KaRIn in ssh_karin variable. N/A uint 4294967295 0 to 4194811391 1
ssh_karin_uncert 1-sigma uncertainty on the sea surface height from the KaRIn measurement. m ushort 65535 0 to 60000 0.0001
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
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 9.9692099683869E+36 N/A 1
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