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Description

The SWOT Level 2 Water Mask Raster Image 250m Data Product from the Surface Water Ocean Topography (SWOT) mission provides global surface water elevation and inundation extent derived from high rate (HR) measurements from the Ka-band Radar Interferometer (KaRIn) on SWOT. 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.\r\n<br>
Water surface elevation, area, water fraction, backscatter, geophysical information are provided in geographically fixed scenes at 250 meter horizontal resolution in Universal Transverse Mercator (UTM) projection. Available in netCDF-4 file format. On-demand processing available to users for different resolutions, sampling grids, scene sizes, and file formats.<br>
Please note that this collection contains SWOT Version C science data products.<br>
<br>This collection is a sub-collection of its parent: https://podaac.jpl.nasa.gov/dataset/SWOT_L2_HR_Raster_2.0

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
250 Meters x 250 Meters
Geographic Region
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
C2799438288-POCLOUD
Data State
SUPERSEDED
Number of Files/Granules
530132
Processing Level
2
Published
Updated
Science Keywords
Rivers/Streams ,
Surface Water Processes/Measurements ,
Lakes/Reservoirs

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 Water Mask Raster Image Data Product [Data set]. NASA Physical Oceanography Distributed Active Archive Center. https://doi.org/10.5067/SWOT-RASTER-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
cross_track Approximate cross-track location of the pixel. m float 9.96921E+36 -75000 to 75000 1
crs UTM zone coordinate reference system. N/A string N/A N/A 1
dark_frac Fraction of pixel water surface area covered by dark water. l float 9.96921E+36 -1000 to 10000 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 float 9.96921E+36 -150 to 150 1
height_cor_xover Height correction from KaRIn crossover calibration. The correction is applied before geolocation but reported as an equivalent height correction. m float 9.96921E+36 -10 to 10 1
ice_clim_flag Climatological ice cover flag indicating whether the pixel is ice-covered on the day of the observation based on external climatological information (not the SWOT measurement). Values of 0, 1, and 2 indicate that the pixel is likely not ice covered, may or may not be partially or fully ice covered, and likely fully ice covered, respectively. N/A ubyte 255 0 to 2 1
ice_dyn_flag Dynamic ice cover flag indicating whether the surface is ice-covered on the day of the observation based on analysis of external satellite optical data. Values of 0, 1, and 2 indicate that the pixel is not ice covered, partially ice covered, and fully ice covered, respectively. N/A ubyte 255 0 to 2 1
illumination_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 00:00:00.000 double 9.9692099683869E+36 N/A 1
illumination_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 [illumination_time:tai_utc_difference]. seconds since 2000-01-01 00:00:00.000 double 9.9692099683869E+36 N/A 1
inc Incidence angle. degrees float 9.96921E+36 0 to 90 1
iono_cor_gim_ka Equivalent vertical correction due to ionosphere delay. The reported water surface elevation, 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 water surface elevation results in the uncorrected pixel height. m float 9.96921E+36 -0.5 0 1
latitude Geodetic latitude [-80,80] (degrees north of equator) of the pixel. degrees_north double 9.9692099683869E+36 -80 to 80 1
layover_impact Estimate of the water surface elevation error caused by layover. m float 9.96921E+36 -999999 to 999999 1
load_tide_fes Geocentric load tide height. The effect of the ocean tide loading of the Earth’s crust. m float 9.96921E+36 -0.2 to 0.2 1
load_tide_got Geocentric load tide height. The effect of the ocean tide loading of the Earth’s crust. This value is reported for reference but is not applied to the reported height. m float 9.96921E+36 -0.2 to 0.2 1
longitude Geodetic longitude [-180,180) (east of the Greenwich meridian) of the pixel. degrees_east double 9.9692099683869E+36 -180 to 180 1
model_dry_tropo_cor Equivalent vertical correction due to dry troposphere delay. The reported water surface elevation, 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 water surface elevation results in the uncorrected pixel height. m float 9.96921E+36 -3 to -1.5 1
model_wet_tropo_cor Equivalent vertical correction due to wet troposphere delay. The reported water surface elevation, 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 water surface elevation results in the uncorrected pixel height. m float 9.96921E+36 -1 0 1
n_other_pix Number of pixel cloud samples used in aggregation of quantities not related to water surface elevation, water surface area, water fraction or sigma0. l uint 4294967295 0 to 999999 1
n_sig0_pix Number of pixel cloud samples used in sigma0 aggregation. l uint 4294967295 0 to 999999 1
n_water_area_pix Number of pixel cloud samples used in water surface area and water fraction aggregation. l uint 4294967295 0 to 999999 1
n_wse_pix Number of pixel cloud samples used in water surface elevation aggregation. l uint 4294967295 0 to 999999 1
pole_tide Geocentric pole tide height. The total of the contribution from the solid-Earth (body) pole tide height and the load pole tide height (i.e., the effect of the ocean pole tide loading of the Earth’s crust). m float 9.96921E+36 -0.2 to 0.2 1
sig0 Normalized radar cross section (sigma0) in real, linear units (not decibels). The value may be negative due to noise subtraction. 1 float 9.96921E+36 -999999 to 999999 1
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. 1 float 9.96921E+36 1 to 10 1
sig0_qual Summary quality indicator for the sigma0 quantities. A value of 0 indicates a nominal measurement, 1 indicates a suspect measurement, 2 indicates a degraded measurement, and 3 indicates a bad measurement. N/A ubyte 255 0 to 3 1
sig0_qual_bitwise Bitwise quality indicator for the sigma0 quantities. If this word is interpreted as an unsigned integer, a value of 0 indicates good data, positive values less than 32768 represent suspect data, values greater than or equal to 32768 but less than 8388608 represent degraded data, and values greater than or equal to 8388608 represent bad data. N/A uint 4294967295 0 to 4111364519 1
sig0_uncert 1-sigma uncertainty in sigma0. The value is provided in linear units. This value is a one-sigma additive (not multiplicative) uncertainty term, which can be added to or subtracted from sigma0. 1 float 9.96921E+36 -999999 to 999999 1
solid_earth_tide Solid-Earth (body) tide height. The zero-frequency permanent tide component is not included. m float 9.96921E+36 -1 to 1 1
water_area Surface area of the water pixels. m^2 float 9.96921E+36 -2000000 to 2000000000 1
water_area_qual Summary quality indicator for the water surface area and water fraction quantities. A value of 0 indicates a nominal measurement, 1 indicates a suspect measurement, 2 indicates a degraded measurement, and 3 indicates a bad measurement. N/A ubyte 255 0 to 3 1
water_area_qual_bitwise Bitwise quality indicator for the water surface area and water fraction quantities. If this word is interpreted as an unsigned integer, a value of 0 indicates good data, positive values less than 32768 represent suspect data, values greater than or equal to 32768 but less than 8388608 represent degraded data, and values greater than or equal to 8388608 represent bad data. N/A uint 4294967295 0 to 4111233454 1
water_area_uncert 1-sigma uncertainty in the water surface area. m^2 float 9.96921E+36 0 to 2000000000 1
water_frac Fraction of the pixel that is water. 1 float 9.96921E+36 -1000 to 10000 1
water_frac_uncert 1-sigma uncertainty in the water fraction. 1 float 9.96921E+36 0 to 999999 1
wse Water surface elevation of the pixel above the geoid and after using models to subtract the effects of tides (solid_earth_tide, load_tide_fes, pole_tide). m float 9.96921E+36 -1500 to 15000 1
wse_qual Summary quality indicator for the water surface elevation quantities. A value of 0 indicates a nominal measurement, 1 indicates a suspect measurement, 2 indicates a degraded measurement, and 3 indicates a bad measurement. N/A ubyte 255 0 to 3 1
wse_qual_bitwise Bitwise quality indicator for the water surface elevation quantities. If this word is interpreted as an unsigned integer, a value of 0 indicates good data, positive values less than 32768 represent suspect data, values greater than or equal to 32768 but less than 8388608 represent degraded data, and values greater than or equal to 8388608 represent bad data. N/A uint 4294967295 0 to 4114378918 1
wse_uncert 1-sigma uncertainty in the water surface elevation. m float 9.96921E+36 0 to 999999 1
x UTM easting coordinate of the pixel. m double 9.9692099683869E+36 -10000000 to 10000000 1
y UTM northing coordinate of the pixel. m double 9.9692099683869E+36 -20000000 to 20000000 1
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