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Description

This dataset includes simulated water surface elevations that resemble the Ka-band Interferometer (KaRIn) measurements by the Surface Water and Ocean Topography (SWOT) mission. SWOT will provide a global coverage but this simulated subset focuses on the North America continent. The simulated SWOT KaRIN swaths span 128 km in the cross-swath direction with a 20-km nadir gap. The primary product contains the following: 1. Geolocated elevations (latitude, longitude, and height) 2. Classification mask (water/land flags, and water fraction) 3. Surface areas (projected pixel area on the ground) 4. Relevant data needed to compute and aggregate height and area uncertainties. Additional information includes: 1. Meta data (global instrument parameters) 2. Time varying parameters (TVP), which include sensor position, velocity, altitude, and time 3. Noise power estimates 4. Quality flags 5. Interferogram measurements (power and phase) and range and azimuth indices 6. Geophysical and crossover-calibration correction values. These additional fields are provided to improve the utility of the product and to facilitate generation of downstream products. Note that this is a simulated SWOT product and not suited for any scientific exploration.

Product Summary

Platforms
COMPUTERS
Instruments
Computer
Spatial Extent

N: 52 S: 24 E: -82 W: -113

Spatial Resolution
20 Meters x 20 Meters
Geographic Region
NORTH AMERICA
Coordinate System
GEODETIC
Granule Spatial Representation
GEODETIC
Temporal Extent
2022-08-01 to 2022-08-22
Data Partner
Physical Oceanography Distributed Active Archive Center, Jet Propulsion Laboratory, NASA (NASA/JPL/PODAAC)
Concept ID
C2263383386-POCLOUD
Data State
ACTIVE
Number of Files/Granules
1644
Processing Level
2
Published
Science Keywords
Lakes/Reservoirs ,
Rivers/Streams ,
Stage Height ,
Total Surface Water

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

CNES. (2022). SWOT Simulated Level 2 North America Continent KaRIn High Rate Water Mask Pixel Cloud Product Version 1.0 [Data set]. NASA Physical Oceanography Distributed Active Archive Center. https://doi.org/10.5067/KARIN-2PIX1 Date Accessed: 2025-12-14

Documents

USER'S GUIDE

ALGORITHM DOCUMENTATION

DATA CITATION GUIDELINES

GENERAL DOCUMENTATION

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
/noise/noise_minus_y Noise power for the minus_y channel expressed in linear units (arbitrary units that give noise-equivalent sigma0 when normalized by the X factor). 1 float 9.96921E+36 0 to 1.0E+20 1
/noise/noise_plus_y Noise power for the plus_y channel expressed in linear units (arbitrary units that give noise-equivalent sigma0 when normalized by the X factor). 1 float 9.96921E+36 0 to 1.0E+20 1
/pixel_cloud/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
/pixel_cloud/azimuth_index Rare interferogram azimuth index (indexed from 0). 1 int 2147483647 0 to 999999 1
/pixel_cloud/bright_land_flag Flag indicating areas that are not typically water but are expected to be bright (e.g., urban areas, ice). Flag value 2 indicates cases where prior data indicate land, but where prior_water_prob indicates possible water. N/A byte 127 0 to 2 1
/pixel_cloud/classification Flags indicating water detection results. N/A byte 127 1 to 24 1
/pixel_cloud/coherent_power Power computed by combining the plus_y and minus_y channels coherently by co-aligning the phases (arbitrary units that give sigma0 when noise subtracted and normalized by the X factor). 1 float 9.96921E+36 0 to 999999 1
/pixel_cloud/cross_track Approximate cross-track location of the pixel. m float 9.96921E+36 -75000 to 75000 1
/pixel_cloud/darea_dheight Sensitivity of the pixel area to the reference height. m^2/m float 9.96921E+36 -999999 to 999999 1
/pixel_cloud/dheight_dbaseline Sensitivity of the height estimate to the interferometric baseline. m/m float 9.96921E+36 -999999 to 999999 1
/pixel_cloud/dheight_dphase Sensitivity of the height estimate to the interferogram phase. m/radian float 9.96921E+36 -999999 to 999999 1
/pixel_cloud/dheight_drange Sensitivity of the height estimate to the range (delay). m/m float 9.96921E+36 -999999 to 999999 1
/pixel_cloud/dheight_droll Sensitivity of the height estimate to the spacecraft roll. m/degrees float 9.96921E+36 -999999 to 999999 1
/pixel_cloud/dlatitude_dphase Sensitivity of the latitude estimate to the interferogram phase. degrees/radian float 9.96921E+36 -999999 to 999999 1
/pixel_cloud/dlongitude_dphase Sensitivity of the longitude estimate to the interferogram phase. degrees/radian float 9.96921E+36 -999999 to 999999 1
/pixel_cloud/eff_num_medium_looks Effective number of independent looks taken in forming the medium interferogram (after adaptive averaging). 1 float 9.96921E+36 0 to 999999 1
/pixel_cloud/eff_num_rare_looks Effective number of independent looks taken to form the rare interferogram. 1 float 9.96921E+36 0 to 999999 1
/pixel_cloud/false_detection_rate Probability of falsely detecting water when there is none. 1 float 9.96921E+36 0 to 1 1
/pixel_cloud/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
/pixel_cloud/height Height of the pixel above the reference ellipsoid. m float 9.96921E+36 -1500 to 15000 1
/pixel_cloud/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
/pixel_cloud/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
/pixel_cloud/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
/pixel_cloud/inc Incidence angle. degrees float 9.96921E+36 0 to 999999 1
/pixel_cloud/instrument_attitude_cor Term that incorporates all calibration corrections applied to attitude before geolocation. degrees float 9.96921E+36 -999999 to 999999 1
/pixel_cloud/instrument_baseline_cor Term that incorporates all calibration corrections applied to baseline before geolocation. m float 9.96921E+36 -999999 to 999999 1
/pixel_cloud/instrument_phase_cor Term that incorporates all calibration corrections applied to phase before geolocation. radians float 9.96921E+36 -999999 to 999999 1
/pixel_cloud/instrument_range_cor Term that incorporates all calibration corrections applied to range before geolocation. m float 9.96921E+36 -999999 to 999999 1
/pixel_cloud/interferogram Complex unflattened rare interferogram. 1 float 9.96921E+36 -999999 to 999999 1
/pixel_cloud/iono_cor_gim_ka Equivalent vertical correction due to ionosphere delay. 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 pixel height results in the uncorrected pixel height. m float 9.96921E+36 -0.5 0 1
/pixel_cloud/latitude Geodetic latitude [-80,80] (degrees north of equator) of the pixel. degrees_north double 9.9692099683869E+36 -80 to 80 1
/pixel_cloud/layover_impact Estimate of the height error caused by layover, which may not be reliable on a pixel by pixel basis, but may be useful to augment aggregated height uncertainties. m float 9.96921E+36 -999999 to 999999 1
/pixel_cloud/load_tide_fes 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
/pixel_cloud/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
/pixel_cloud/longitude Longitude [-180,180) (east of the Greenwich meridian) of the pixel. degrees_east double 9.9692099683869E+36 -180 to 180 1
/pixel_cloud/missed_detection_rate Probability of falsely detecting no water when there is water. 1 float 9.96921E+36 0 to 1 1
/pixel_cloud/model_dry_tropo_cor Equivalent vertical correction due to dry troposphere delay. 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 pixel height results in the uncorrected pixel height. m float 9.96921E+36 -3 to -1.5 1
/pixel_cloud/model_wet_tropo_cor Equivalent vertical correction due to wet troposphere delay. 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 pixel height results in the uncorrected pixel height. m float 9.96921E+36 -1 0 1
/pixel_cloud/phase_noise_std Estimate of the phase noise standard deviation. radians float 9.96921E+36 -999999 to 999999 1
/pixel_cloud/phase_unwrapping_region Phase unwrapping region index. 1 int 2147483647 -1 to 99999999 1
/pixel_cloud/pixc_qual Quality flag for pixel cloud data N/A byte 127 0 to 1 1
/pixel_cloud/pixel_area Pixel area. m^2 float 9.96921E+36 0 to 999999 1
/pixel_cloud/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
/pixel_cloud/power_minus_y Power for the minus_y channel (arbitrary units that give sigma0 when noise subtracted and normalized by the X factor). 1 float 9.96921E+36 0 to 999999 1
/pixel_cloud/power_plus_y Power for the plus_y channel (arbitrary units that give sigma0 when noise subtracted and normalized by the X factor). 1 float 9.96921E+36 0 to 999999 1
/pixel_cloud/prior_water_prob Prior probability of water occurring. 1 float 9.96921E+36 0 to 1 1
/pixel_cloud/range_index Rare interferogram range index (indexed from 0). 1 int 2147483647 0 to 999999 1
/pixel_cloud/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
/pixel_cloud/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
/pixel_cloud/water_frac Noisy estimate of the fraction of the pixel that is water. 1 float 9.96921E+36 -1000 to 10000 1
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