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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.
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).
Please note that this collection contains SWOT Version C science data products.
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.
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.
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SWOT. (2024). SWOT Level 2 KaRIn Low Rate Sea Surface Height Data Product [Dataset]. NASA Physical Oceanography Distributed Active Archive Center. https://doi.org/10.5067/SWOT-SSH-2.0 Date Accessed: 2026-08-09
SWOT. (2024). SWOT Level 2 KaRIn Low Rate Sea Surface Height Data Product [Dataset]. NASA Physical Oceanography Distributed Active Archive Center. https://doi.org/10.5067/SWOT-SSH-2.0 Date Accessed: 2026-08-09
SWOT. “SWOT Level 2 KaRIn Low Rate Sea Surface Height Data Product.” NASA Physical Oceanography Distributed Active Archive Center, 2024, https://doi.org/10.5067/SWOT-SSH-2.0. Date Accessed: 2026-08-09
Buijsman, Maarten C., Waterhouse, Amy F., Zaron, Edward D., Yadidya, Badarvada, Xu, Chengzhu, Whitley, Victoria, Wenegrat, Jacob O., Wang, Jinbo, Wallcraft, Alan J., Varma, Dheeraj, Tchonang, Babette C., Siyanbola, Oladeji, Shriver, Jay F., Sheremet, Vitalii A., Send, Uwe, Raja, Keshav J., Polzin, Kurt, Ngodock, Hans E., Moulin, Aurelie J., Meiners, Grant, Lucas, Andrew J., Lankhorst, Matthias, Kuehl, Joseph J., Kelly, Samuel M., Kachelein, Luke, Huang, Yonglin, Griffin, Caeli, Girton, James B., Farrar, J. Thomas, Delpech, Audrey, Chen, Zihan, Chassignet, Eric P., Carrier, Matthew J., Bracco, Annalisa, Arbic, Brian K., Andres, Magdalena, Abdulfatai, Mujeeb A.
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.
7-state surface type classification computed from a mask built with MODIS and GlobCover data.
N/A
ubyte
255
0 to 6
1
N/A
distance_to_coast
Approximate distance to the nearest coast point along the Earth surface.
m
ushort
65535
0 to 21000
1000
N/A
dynamic_ice_flag
Dynamic ice flag for the location of the KaRIn measurement.
N/A
ubyte
255
0 to 3
1
N/A
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
N/A
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
N/A
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
N/A
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
N/A
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
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
longitude
Longitude of measurement. East longitude relative to Greenwich meridian.
degrees_east
int
2147483647
0 to 359999999
1.0E-6
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
num_pt_avg
Number of native unsmoothed, beam-combined KaRIn samples averaged.
1
ushort
65535
0 to 289
1
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
rain_flag
Flag indicates that signal is attenuated, probably from rain.
N/A
ubyte
255
0 to 3
1
N/A
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
N/A
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
N/A
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
N/A
ssha_karin_qual
Quality flag for the SSHA from KaRIn in the ssha_karin variable.
N/A
uint
4294967295
0 to 4261920255
1
N/A
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
N/A
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
N/A
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
N/A
ssh_karin_qual
Quality flag for sea surface height from KaRIn in ssh_karin variable.
N/A
uint
4294967295
0 to 4194811391
1
N/A
ssh_karin_uncert
1-sigma uncertainty on the sea surface height from the KaRIn measurement.
m
ushort
65535
0 to 60000
0.0001
N/A
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
N/A
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].