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Description

The Sensory Geophysical Data Record (SGDR) files contain full accuracy altimeter data, with a high precision orbit (accuracy ~1.5 cm). The instruments on Jason-1 make direct observations of the following quantities: altimeter range, significant wave height, ocean radar backscatter cross-section (a measure of wind speed), ionospheric electron content (derived by a simple formula), tropospheric water content, mean sea surface, and position relative to the GPS satellite constellation. The SGDR contain all relevant corrections needed to calculate the sea surface height. It also contains the 20Hz waveforms that are required for retracking. The SGDR is an expert level product, if you do not require the waveforms then the GDR/GPN or GPR will be more suited for your needs.

Product Summary

Platforms
JASON-1
Instruments
TRSR ,
DORIS ,
JASON-1 Microwave Radiometer ,
POSEIDON-2
Spatial Extent

N: 66.15 S: -66.15 E: 180 W: -180

Location
GLOBAL
Coordinate System
CARTESIAN
Granule Spatial Representation
CARTESIAN
Temporal Extent
2002-01-14 to 2012-03-03
Data Partner
Physical Oceanography Distributed Active Archive Center, Jet Propulsion Laboratory, NASA (NASA/JPL/PODAAC)
Concept ID
C1940472420-POCLOUD
Data State
COMPLETE
Number of Files/Granules
92126
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

JASON-1. (2015). Jason-1 SGDR version E NetCDF [Data set]. NASA Physical Oceanography Distributed Active Archive Center. https://doi.org/10.5067/J1GPS-NC00E Date Accessed: 2026-05-13

Documents

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Variables

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.

Name Description Units Data Type Fill Value Valid Range Scale Factor Offset
meas_ind Set to be compliant with the CF-1.1 convention count byte N/A N/A 1 N/A
modeled_instr_corr_range_c C band modeled instrumental correction on altimeter range m short 32767 N/A 0.0001 N/A
modeled_instr_corr_range_ku Ku band modeled instrumental correction on altimeter range m short 32767 N/A 0.0001 N/A
modeled_instr_corr_sig0_c C band modeled instrumental correction on backscatter coefficient dB short 32767 N/A 0.01 N/A
modeled_instr_corr_sig0_ku Ku band modeled instrumental correction on backscatter coefficient dB short 32767 N/A 0.01 N/A
modeled_instr_corr_swh_c C band modeled instrumental correction on significant waveheight m short 32767 N/A 0.001 N/A
modeled_instr_corr_swh_ku Ku band modeled instrumental correction on significant waveheight m short 32767 N/A 0.001 N/A
model_dry_tropo_corr Computed at the altimeter time-tag from the interpolation of 2 meteorological fields that surround the altimeter time-tag. A dry tropospheric correction must be added (negative value) to the instrument range to correct this range measurement for dry tropospheric range delays of the radar pulse. See Jason-1 User Handbook m short 32767 N/A 0.0001 N/A
model_dry_tropo_corr_era Courtesy of ECMWF as provider of met data for the atmospheric corrections. Computed at the altimeter time-tag from the interpolation of 2 ERA meteorological fields that surround the altimeter time-tag. A dry tropospheric correction must be added (negative value) to the instrument range to correct this range measurement for dry tropospheric range delays of the radar pulse. See Jason-1 User Handbook m short 32767 N/A 0.0001 N/A
model_wet_tropo_corr Computed at the altimeter time-tag from the interpolation of 2 meteorological fields that surround the altimeter time-tag. A wet tropospheric correction must be added (negative value) to the instrument range to correct this range measurement for wet tropospheric range delays of the radar pulse. See Jason-1 User Handbook m short 32767 N/A 0.0001 N/A
model_wet_tropo_corr_era Courtesy of ECMWF as provider of met data for the atmospheric corrections. Computed at the altimeter time-tag from the interpolation of 2 ERA meteorological fields that surround the altimeter time-tag. A wet tropospheric correction must be added (negative value) to the instrument range to correct this range measurement for wet tropospheric range delays of the radar pulse. See Jason-1 User Handbook m short 32767 N/A 0.0001 N/A
mqe_20hz_c Mean Quadratic Error between the waveforms samples and the corresponding model samples built from the ocean retracking outputs count short 32767 N/A 0.0001 N/A
mqe_20hz_ku Mean Quadratic Error between the waveforms samples and the corresponding model samples built from the ocean retracking outputs count short 32767 N/A 0.0001 N/A
net_instr_corr_range_c Sum of distance antenna-COG (cog_corr), USO drift correction (uso_corr), internal path correction (internal_path_delay_corr_c), Doppler correction (doppler_corr_c), modeled instrumental errors correction (modeled_instr_corr_range_c) and system bias. Updated to account for reference plane and internal path delay m int 2147483647 N/A 0.0001 N/A
net_instr_corr_range_ku Sum of distance antenna-COG (cog_corr), USO drift correction (uso_corr), internal path correction (internal_path_delay_corr_ku), Doppler correction (doppler_corr_ku), modeled instrumental errors correction (modeled_instr_corr_range_ku) and system bias. Updated to account for reference plane and internal path delay m int 2147483647 N/A 0.0001 N/A
net_instr_corr_sig0_c Sum of AGC instrumental errors correction, internal calibration correction (internal_corr_sig0_c) and modeled instrumental errors correction (modeled_instr_corr_sig0_c) - system bias not included dB short 32767 N/A 0.01 N/A
net_instr_corr_sig0_ku Sum of AGC instrumental errors correction, internal calibration correction (internal_corr_sig0_ku) and modeled instrumental errors correction (modeled_instr_corr_sig0_ku) - system bias not included dB short 32767 N/A 0.01 N/A
net_instr_corr_swh_c Sum of modeled instrumental errors correction (modeled_instr_corr_swh_c) and system bias m short 32767 N/A 0.001 N/A
net_instr_corr_swh_ku Sum of modeled instrumental errors correction (modeled_instr_corr_swh_ku) and system bias m short 32767 N/A 0.001 N/A
number_of_iterations_c 20 Hz number of iterations of the ocean retracking in C band count byte 127 N/A 1 N/A
number_of_iterations_ku 20 Hz number of iterations of the ocean retracking in Ku band count byte 127 N/A 1 N/A
ocean_tide_equil This value has already been added to the two geocentric ocean tide height values recorded in the product (ocean_tide_sol1 and ocean_tide_sol2). The permanent tide (zero frequency) is not included in this parameter because it is included in the geoid and mean sea surface (geoid, mean_sea_surface). See Jason-1 User Handbook m short 32767 N/A 0.0001 N/A
ocean_tide_non_equil This parameter is computed as a correction to the parameter ocean_tide_equil. This value can be added to ocean_tide_equil (or ocean_tide_sol1, ocean_tide_sol2) so that the resulting value models the total non equilibrium ocean tide height. See Jason-1 User Handbook m short 32767 N/A 0.0001 N/A
ocean_tide_sol1 Solution 1 corresponds to GOT4.10 model. Includes the corresponding loading tide (load_tide_sol1) and equilibrium long-period ocean tide height (ocean_tide_equil). The permanent tide (zero frequency) is not included in this parameter because it is included in the geoid and mean sea surface (geoid, mean_sea_surface). See Jason-1 User Handbook m int 2147483647 N/A 0.0001 N/A
ocean_tide_sol2 Solution 2 corresponds to FES2014 model. Includes the corresponding loading tide (load_tide_sol2) and equilibrium long-period ocean tide height (ocean_tide_equil). The permanent tide (zero frequency) is not included in this parameter because it is included in the geoid and mean sea surface (geoid, mean_sea_surface). See Jason-1 User Handbook m int 2147483647 N/A 0.0001 N/A
off_nadir_angle_wf_ku square of the off nadir angle computed from Ku waveforms degrees^2 short 32767 N/A 0.0001 N/A
orb_alt_rate The reference surface for the orbital altitude rate is the combined mean_sea_surface/geoid surface. It is used to compute the Doppler correction on the altimeter range (doppler_corr_ku, doppler_corr_c) m/s short 32767 N/A 0.01 N/A
orb_state_flag_rest 0 characterizes a mission operations orbit that is computed during a maneuver period, 1 stands for an adjusted mission operations orbit, 2 stands for an extrapolated mission operations orbit, 3 stands for an adjusted (preliminary/precise) orbit, 4 indicates that the (preliminary/precise) orbit is estimated during a maneuver period, 5 indicates that the (preliminary/precise) orbit is interpolated over a tracking data gap, 6 means that the (preliminary/precise) orbit is extrapolated for a duration less than 1 day, 7 means that the (preliminary/precise) orbit is extrapolated for a duration that ranges from 1 day to 2 days, 8 means that the (preliminary/precise) orbit is extrapolated for a duration larger than 2 days, or that the orbit is extrapolated just after a maneuver, 9 stands for the DORIS DIODE navigator orbit. The nominal value is 3 N/A byte 127 N/A 1 N/A
peakiness_20hz_c 20 Hz peakiness on C band waveforms count short 32767 N/A 0.001 N/A
peakiness_20hz_ku 20 Hz peakiness on Ku band waveforms count short 32767 N/A 0.001 N/A
pole_tide See Jason-1 User Handbook m short 32767 N/A 0.0001 N/A
qual_alt_1hz_off_nadir_angle_wf_ku quality flag for 1 Hz altimeter data: off nadir angle from Ku band N/A byte 127 N/A 1 N/A
qual_alt_1hz_range_c quality flag for 1 Hz altimeter data: C band range N/A byte 127 N/A 1 N/A
qual_alt_1hz_range_ku quality flag for 1 Hz altimeter data: Ku band range N/A byte 127 N/A 1 N/A
qual_alt_1hz_sig0_c quality flag for 1 Hz altimeter data: C band backscatter coefficient N/A byte 127 N/A 1 N/A
qual_alt_1hz_sig0_ku quality flag for 1 Hz altimeter data: Ku band backscatter coefficient N/A byte 127 N/A 1 N/A
qual_alt_1hz_swh_c quality flag for 1 Hz altimeter data: C band SWH N/A byte 127 N/A 1 N/A
qual_alt_1hz_swh_ku quality flag for 1 Hz altimeter data: Ku band SWH N/A byte 127 N/A 1 N/A
qual_inst_corr_1hz_range_c quality flag for 1 Hz instrumental correction: C band range N/A byte 127 N/A 1 N/A
qual_inst_corr_1hz_range_ku quality flag for 1 Hz instrumental correction: Ku band range N/A byte 127 N/A 1 N/A
qual_inst_corr_1hz_sig0_c quality flag for 1 Hz instrumental correction: C band backscatter coefficient N/A byte 127 N/A 1 N/A
qual_inst_corr_1hz_sig0_ku quality flag for 1 Hz instrumental correction: Ku band backscatter coefficient N/A byte 127 N/A 1 N/A
qual_inst_corr_1hz_swh_c quality flag for 1 Hz instrumental correction: C band SWH N/A byte 127 N/A 1 N/A
qual_inst_corr_1hz_swh_ku quality flag for 1 Hz instrumental correction: Ku band SWH N/A byte 127 N/A 1 N/A
qual_rad_1hz_tb187 quality flag for 1 Hz radiometer data: 18.7 GHz brightness temperature N/A byte 127 N/A 1 N/A
qual_rad_1hz_tb238 quality flag for 1 Hz radiometer data: 23.8 GHz brightness temperature N/A byte 127 N/A 1 N/A
qual_rad_1hz_tb340 quality flag for 1 Hz radiometer data: 34.0 GHz brightness temperature N/A byte 127 N/A 1 N/A
rad_averaging_flag radiometer along-track averaging flag N/A byte 127 N/A 1 N/A
rad_distance_to_land Shortest distance between nadir sub-satellite point and land m int 2147483647 N/A 1 N/A
rad_land_frac_187 radiometer 18.7 GHz antenna gain weighted land fraction in main beam % short 32767 N/A 0.01 N/A
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