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Description

Same as L2_NALT_GDR, using preliminary values for some auxiliary data. Uses Medium-accuracy (preliminary) Orbit Ephemeris (MOE). Available with latency of < 1.5 days. Discrete measurements at nadir for each half orbit, along the ground track. Available in netCDF-4 file format.
<br>This collection is a sub-collection of its parent: https://podaac.jpl.nasa.gov/dataset/SWOT_L2_NALT_IGDR_D

Product Summary

Platforms
SWOT
Instruments
Jason-class Altimeter ,
AMR
Spatial Extent

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

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
C3317113901-POCLOUD
Data State
ACTIVE
Number of Files/Granules
6131
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. (2025). SWOT Level 2 Nadir Altimeter Interim Geophysical Data Record with Waveforms [Data set]. NASA Physical Oceanography Distributed Active Archive Center. https://doi.org/10.5067/SWOT-NALT-IGDR-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
/data_01/altitude Altitude of satellite above the reference ellipsoid. Associated quality flag is orb_state_diode_flag for the OGDR products, orb_state_rest_flag for the IGDR and GDR products m int 2147483647 N/A 0.0001
/data_01/altitude_rate The reference surface for the orbital altitude rate is the combined mean_sea_surface_cnescls/geoid surface. It is used to compute the Doppler correction on the altimeter range (/data_01/ku/range_cor_doppler, /data_01/c/range_cor_doppler) m/s short 32767 N/A 0.01
/data_01/alt_state_band_seq_flag altimeter state flag: Ku/C band sequencing N/A byte 127 N/A 1
/data_01/angle_of_approach_to_coast Angle of approach to the closest coast. 0 is parallel to the coast with the land on the right. Positive values indicate the satellite is approaching the land. Negative values indicate the satellite is leaving the land. Values close to +/-180 degrees have the land on the left degrees short 32767 N/A 0.01
/data_01/c/agc AGC is corrected for instrumental errors due to the imperfections of the on-board attenuators dB short 32767 N/A 0.01
/data_01/c/agc_numval number of valid points used to compute C band AGC count byte 127 0 to 20 1
/data_01/c/agc_rms Compression of C band high rate elements is preceded by a detection of outliers. Only valid high-rate values are used to compute this element dB short 32767 N/A 0.01
/data_01/c/alt_state_band_status_flag altimeter state flag: C band status N/A byte 127 N/A 1
/data_01/c/alt_state_c_band_flag altimeter state flag: C bandwidth used N/A byte 127 N/A 1
/data_01/c/range_cor_ocean_net_instr Sum of distance antenna-COG (/data_01/range_cor_cog), USO drift correction (/data_01/range_cor_uso), internal path correction (range_cor_internal_path), Doppler correction (range_cor_doppler), modeled instrumental errors correction (range_cor_ocean_model_instr) and system bias m int 2147483647 N/A 0.0001
/data_01/c/range_cor_ocean_net_instr_qual Threshold control of range_cor_ocean_net_instr N/A byte 127 N/A 1
/data_01/c/range_ocean All instrumental corrections included, i.e. distance antenna-COG (/data_01/range_cor_cog), USO drift correction (/data_01/range_cor_uso), internal path correction (range_cor_internal_path), Doppler correction (range_cor_doppler), modeled instrumental errors correction (range_cor_ocean_model_instr) and system bias m int 2147483647 N/A 0.0001
/data_01/c/range_ocean_compression_qual quality flag for 1 Hz altimeter data: C band range N/A byte 127 N/A 1
/data_01/c/range_ocean_numval number of valid points for C band range count byte 127 0 to 20 1
/data_01/c/range_ocean_rms Compression of C band high rate elements is preceded by a detection of outliers. Only valid high-rate values are used to compute this element m short 32767 N/A 0.0001
/data_01/c/sea_state_bias A sea state bias correction must be added (negative value) to the instrument range to correct this range measurement for sea state delays of the radar pulse. This element should not be used over land. See SWOT Nadir Altimeter User Handbook m short 32767 N/A 0.0001
/data_01/c/sea_state_bias_adaptive A sea state bias correction must be added (negative value) to the instrument range to correct this range measurement for sea state delays of the radar pulse. This element should not be used over land. See SWOT Nadir Altimeter User Handbook m short 32767 N/A 0.0001
/data_01/c/sea_state_bias_mle3 A sea state bias correction must be added (negative value) to the instrument range to correct this range measurement for sea state delays of the radar pulse. This element should not be used over land. See SWOT Nadir Altimeter User Handbook m short 32767 N/A 0.0001
/data_01/c/sig0_cor_atm Based either on the radiometer (if available) or atmospheric model (otherwise). The flag sig0_cor_atm_source indicates whether the atmospheric model has been used dB short 32767 N/A 0.01
/data_01/c/sig0_cor_ocean_net_instr Sum of AGC instrumental errors correction, internal calibration correction (sig0_cor_calibration) and modeled instrumental errors correction (sig0_cor_ocean_model_instr) - system bias not included dB short 32767 N/A 0.01
/data_01/c/sig0_cor_ocean_net_instr_qual Threshold control of sig0_cor_ocean_net_instr N/A byte 127 N/A 1
/data_01/c/sig0_ocean All instrumental corrections included, excepted the system bias, i.e. AGC instrumental errors correction, internal calibration correction (sig0_cor_calibration), modeled instrumental errors correction (sig0_cor_ocean_model_instr) and atmospheric attenuation (sig0_cor_atm) dB short 32767 N/A 0.01
/data_01/c/sig0_ocean_compression_qual quality flag for 1 Hz altimeter data: C band backscatter coefficient N/A byte 127 N/A 1
/data_01/c/sig0_ocean_numval number of valid points used to compute C band backscatter coefficient count byte 127 0 to 20 1
/data_01/c/sig0_ocean_rms Compression of C band high rate elements is preceded by a detection of outliers. Only valid high-rate values are used to compute this element dB short 32767 N/A 0.01
/data_01/c/swh_cor_ocean_net_instr Sum of modeled instrumental errors correction (swh_cor_ocean_model_instr) and system bias m short 32767 N/A 0.001
/data_01/c/swh_cor_ocean_net_instr_qual Threshold control of swh_cor_ocean_net_instr N/A byte 127 N/A 1
/data_01/c/swh_ocean All instrumental corrections included, i.e. modeled instrumental errors correction (swh_cor_ocean_model_instr) and system bias m short 32767 N/A 0.001
/data_01/c/swh_ocean_compression_qual quality flag for 1 Hz altimeter data: C band SWH N/A byte 127 N/A 1
/data_01/c/swh_ocean_numval number of valid points used to compute C band significant waveheight count byte 127 0 to 20 1
/data_01/c/swh_ocean_rms Compression of C band high rate elements is preceded by a detection of outliers. Only valid high-rate values are used to compute this element m short 32767 N/A 0.001
/data_01/dac Sum of the high frequency fluctuations correction and of the low frequency inverted barometer correction (inv_bar_cor). See SWOT Nadir Altimeter User Handbook m short 32767 N/A 0.0001
/data_01/depth_or_elevation ocean depth/land elevation m int 2147483647 N/A 1
/data_01/distance_to_coast distance to the coast m int 2147483647 N/A 1
/data_01/geoid Computed from the geoid model with a correction to refer the value to the mean tide system i.e. includes the permanent tide (zero frequency). See SWOT Nadir Altimeter User Handbook m int 2147483647 N/A 0.0001
/data_01/ice_flag See SWOT Nadir Altimeter User Handbook N/A byte 127 N/A 1
/data_01/index_first_20hz_measurement Record counter of the first 20 Hz elementary measurement used to derive the 1 Hz measurement. The total number of 20 Hz measurements associated to 1 Hz time is given by numtotal_20hz_measurement N/A int 2147483647 N/A 1
/data_01/internal_tide_hret See SWOT Nadir Altimeter User Handbook m short 32767 N/A 0.0001
/data_01/internal_tide_hret_interp_qual 0 = 4 points over ocean; 1 = less than 4 points N/A byte 127 N/A 1
/data_01/inv_bar_cor Computed at the altimeter time-tag from the interpolation of 2 meteorological fields that surround the altimeter time-tag. See SWOT Nadir Altimeter User Handbook m short 32767 N/A 0.0001
/data_01/ku/agc AGC is corrected for instrumental errors due to the imperfections of the on-board attenuators dB short 32767 N/A 0.01
/data_01/ku/agc_numval number of valid points used to compute Ku band AGC count byte 127 0 to 20 1
/data_01/ku/agc_rms Compression of Ku band high rate elements is preceded by a detection of outliers. Only valid high-rate values are used to compute this element dB short 32767 N/A 0.01
/data_01/ku/alt_state_band_status_flag altimeter state flag: Ku band status N/A byte 127 N/A 1
/data_01/ku/iono_cor_alt An ionospheric correction must be added (negative value) to the instrument range to correct this range measurement for ionospheric range delays of the radar pulse. See SWOT Nadir Altimeter User Handbook m short 32767 N/A 0.0001
/data_01/ku/iono_cor_alt_adaptive An ionospheric correction must be added (negative value) to the instrument range to correct this range measurement for ionospheric range delays of the radar pulse. See SWOT Nadir Altimeter User Handbook m short 32767 N/A 0.0001
/data_01/ku/iono_cor_alt_filtered An ionospheric correction must be added (negative value) to the instrument range to correct this range measurement for ionospheric range delays of the radar pulse. See SWOT Nadir Altimeter User Handbook m short 32767 N/A 0.0001
/data_01/ku/iono_cor_alt_filtered_adaptive An ionospheric correction must be added (negative value) to the instrument range to correct this range measurement for ionospheric range delays of the radar pulse. See SWOT Nadir Altimeter User Handbook m short 32767 N/A 0.0001
/data_01/ku/iono_cor_alt_filtered_adaptive_qual filtered altimeter ionospheric correction quality flag (adaptive retracking) N/A byte 127 N/A 1
/data_01/ku/iono_cor_alt_filtered_mle3 An ionospheric correction must be added (negative value) to the instrument range to correct this range measurement for ionospheric range delays of the radar pulse. See SWOT Nadir Altimeter User Handbook m short 32767 N/A 0.0001
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