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Description

The SWOT Level 2 Radiometer Brightness Temperatures and Troposphere Operational Geophysical Data Record (OGDR) Version D dataset produced by the Surface Water and Ocean Topography (SWOT) mission provides atmospheric water vapor and liquid water content from the Advanced Microwave Radiometer (AMR), a Jason-class radiometer that measures sea surface brightness temperatures at three microwave frequencies (18.7, 23.8 and 34 GHz). Brightness temperatures are processed to estimate the wet troposphere content, atmospheric attenuation to backscatter, cloud liquid water, water vapor content, and wind speed coincident with each range measurement from the nadir altimeter and applied to correct for altimeter range delays caused by atmospheric effects. SWOT is a joint mission between NASA and CNES that launched on December 16, 2022 and aims to measure ocean surface topography with unprecedented resolution and accuracy, as well as map inland water bodies globally.
The operational radiometer dataset consists of discrete measurements along two tracks located approximately 30-km to the left and right of the satellite nadir. They were processed using the onboard DORIS orbit ephemeris and preliminary calibrations. They are distributed as one file per data downlink in netCDF-4 file format with a nominal latency of < 7 hours.

Product Summary

Platforms
SWOT
Instruments
AMR
Spatial Extent

N: 77.6 S: -77.6 E: 180 W: -180

Geographic Region
GLOBAL
Coordinate System
CARTESIAN
Granule Spatial Representation
CARTESIAN
Temporal Extent
2022-12-16
Data Partner
Physical Oceanography Distributed Active Archive Center, Jet Propulsion Laboratory, NASA (NASA/JPL/PODAAC)
Concept ID
C3317113868-POCLOUD
Data State
ACTIVE
Number of Files/Granules
5374
Processing Level
2
Published
Updated
Science Keywords
Brightness Temperature ,
Atmospheric Water Vapor ,
SIGMA NAUGHT ,
Cloud Liquid Water/Ice ,
Sea Ice ,
LAND/OCEAN/ICE FRACTION ,
Wind Speed

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. (2025). SWOT Level 2 Radiometer Brightness Temperatures and Troposphere Operational Data Product [Data set]. NASA Physical Oceanography Distributed Active Archive Center. https://doi.org/10.5067/SWOT-RAD-OGDR-D 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
/AMR_Side_1/latitude Latitude of measurement [-90, 90]. Positive latitude is North latitude, negative latitude is South latitude. degrees_north int 2147483647 -80000000 to 80000000 1.0E-6
/AMR_Side_1/longitude Longitude of measurement [0,360]. East longitude relative to Greenwich meridian. degrees_east int 2147483647 0 to 359999999 1.0E-6
/AMR_Side_1/rad_atm_cor_sig0_c Value must be added to altimeter backscatter coefficient to correct for atmospheric attenuation. dB short 32767 0 to 32766 0.001
/AMR_Side_1/rad_atm_cor_sig0_c_qual Quality flag for radiometer two-way atmospheric correction to C band backscatter coefficient. N/A byte 127 0 to 1 1
/AMR_Side_1/rad_atm_cor_sig0_ka Value must be added to altimeter backscatter coefficient to correct for atmospheric attenuation. dB short 32767 0 to 32766 0.001
/AMR_Side_1/rad_atm_cor_sig0_ka_qual Quality flag for radiometer two-way atmospheric correction to Ka band backscatter coefficient. N/A byte 127 0 to 1 1
/AMR_Side_1/rad_atm_cor_sig0_ku Value must be added to altimeter backscatter coefficient to correct for atmospheric attenuation. dB short 32767 0 to 32766 0.001
/AMR_Side_1/rad_atm_cor_sig0_ku_qual Quality flag for radiometer two-way atmospheric correction to Ku band backscatter coefficient. N/A byte 127 0 to 1 1
/AMR_Side_1/rad_cloud_liquid_water Integrated cloud liquid water content. kg/m^2 short 32767 0 to 32766 0.01
/AMR_Side_1/rad_cloud_liquid_water_qual Quality flag for radiometer cloud liquid water content. N/A byte 127 0 to 1 1
/AMR_Side_1/rad_coordinates_qual Quality flag for the latitude and longitude coordinates. A value of 0 indicates that the latitude and longitude coordinates are computed using orbit and attitude information, a value of 1 indicates they are computed without attitude information and reflect nadir coordinates, and a value of 2 indicates that they are not computed because orbit information is not available. N/A byte 127 0 to 2 1
/AMR_Side_1/rad_distance_to_land Shortest distance between main beam measurement and land. m int 2147483647 0 to 2147483646 100
/AMR_Side_1/rad_land_frac_187 Fraction of land within the 18.7 GHz main beam. Value is from 0 to 1. 1 short 32767 0 to 10000 0.0001
/AMR_Side_1/rad_land_frac_238 Fraction of land within the 23.8 GHz main beam. Value is from 0 to 1. 1 short 32767 0 to 10000 0.0001
/AMR_Side_1/rad_land_frac_340 Fraction of land within the 34.0 GHz main beam. Value is from 0 to 1. 1 short 32767 0 to 10000 0.0001
/AMR_Side_1/rad_rain_flag Flag indicating if radiometer measurement is invalid due to rain contamination. N/A byte 127 0 to 1 1
/AMR_Side_1/rad_sea_ice_flag Flag indicating if radiometer measurement is invalid due to sea ice contamination. N/A byte 127 0 to 1 1
/AMR_Side_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 byte 127 0 to 2 1
/AMR_Side_1/rad_ta_187 Antenna temperature measurement at 18.7 GHz. K int 2147483647 0 to 36000 0.01
/AMR_Side_1/rad_ta_187_qual Quality flag for 18.7 GHz antenna temperature. N/A byte 127 0 to 1 1
/AMR_Side_1/rad_ta_238 Antenna temperature measurement at 23.8 GHz. K int 2147483647 0 to 36000 0.01
/AMR_Side_1/rad_ta_238_qual Quality flag for 23.8 GHz antenna temperature. N/A byte 127 0 to 1 1
/AMR_Side_1/rad_ta_340 Antenna temperature measurement at 34.0 GHz. K int 2147483647 0 to 36000 0.01
/AMR_Side_1/rad_ta_340_qual Quality flag for 34.0 GHz antenna temperature. N/A byte 127 0 to 1 1
/AMR_Side_1/rad_tb_187 Equalized brightness temperature measurement at 18.7 GHz. Value is smoothed (along-track averaging has been performed). K int 2147483647 0 to 36000 0.01
/AMR_Side_1/rad_tb_187_qual Quality flag for 18.7 GHz equalized brightness temperature. N/A byte 127 0 to 1 1
/AMR_Side_1/rad_tb_238 Equalized brightness temperature measurement at 23.8 GHz. Value is smoothed (along-track averaging has been performed). K int 2147483647 0 to 36000 0.01
/AMR_Side_1/rad_tb_238_qual Quality flag for 23.8 GHz equalized brightness temperature. N/A byte 127 0 to 1 1
/AMR_Side_1/rad_tb_340 Equalized brightness temperature measurement at 34.0 GHz. Value is smoothed (along-track averaging has been performed). K int 2147483647 0 to 36000 0.01
/AMR_Side_1/rad_tb_340_qual Quality flag for 34.0 GHz equalized brightness temperature. N/A byte 127 0 to 1 1
/AMR_Side_1/rad_tmb_187 Main beam brightness temperature measurement at 18.7 GHz. Value is unsmoothed (along-track averaging has not been performed). K int 2147483647 0 to 36000 0.01
/AMR_Side_1/rad_tmb_187_qual Quality flag for 18.7 GHz main beam brightness temperature. N/A byte 127 0 to 1 1
/AMR_Side_1/rad_tmb_238 Main beam brightness temperature measurement at 23.8 GHz. Value is unsmoothed (along-track averaging has not been performed). K int 2147483647 0 to 36000 0.01
/AMR_Side_1/rad_tmb_238_qual Quality flag for 23.8 GHz main beam brightness temperature. N/A byte 127 0 to 1 1
/AMR_Side_1/rad_tmb_340 Main beam brightness temperature measurement at 34.0 GHz. Value is unsmoothed (along-track averaging has not been performed). K int 2147483647 0 to 36000 0.01
/AMR_Side_1/rad_tmb_340_qual Quality flag for 34.0 GHz main beam brightness temperature. N/A byte 127 0 to 1 1
/AMR_Side_1/rad_water_vapor Integrated water vapor content. kg/m^2 short 32767 0 to 32766 0.1
/AMR_Side_1/rad_water_vapor_qual Quality flag for radiometer water vapor content. N/A byte 127 0 to 1 1
/AMR_Side_1/rad_wet_tropo_cor Value must be added to altimeter range to correct for delay due to the wet troposphere. m short 32767 -10000 0 0.0001
/AMR_Side_1/rad_wet_tropo_cor_qual Quality flag for radiometer wet troposphere correction. N/A byte 127 0 to 1 1
/AMR_Side_1/rad_wind_speed Sea surface wind speed. m/s short 32767 0 to 32766 0.01
/AMR_Side_1/rad_wind_speed_qual Quality flag for radiometer wind speed. N/A byte 127 0 to 1 1
/AMR_Side_1/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
/AMR_Side_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
/AMR_Side_2/latitude Latitude of measurement [-90, 90]. Positive latitude is North latitude, negative latitude is South latitude. degrees_north int 2147483647 -80000000 to 80000000 1.0E-6
/AMR_Side_2/longitude Longitude of measurement [0,360]. East longitude relative to Greenwich meridian. degrees_east int 2147483647 0 to 359999999 1.0E-6
/AMR_Side_2/rad_atm_cor_sig0_c Value must be added to altimeter backscatter coefficient to correct for atmospheric attenuation. dB short 32767 0 to 32766 0.001
/AMR_Side_2/rad_atm_cor_sig0_c_qual Quality flag for radiometer two-way atmospheric correction to C band backscatter coefficient. N/A byte 127 0 to 1 1
/AMR_Side_2/rad_atm_cor_sig0_ka Value must be added to altimeter backscatter coefficient to correct for atmospheric attenuation. dB short 32767 0 to 32766 0.001
/AMR_Side_2/rad_atm_cor_sig0_ka_qual Quality flag for radiometer two-way atmospheric correction to Ka band backscatter coefficient. N/A byte 127 0 to 1 1
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