Skip to main content

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: 2026-05-10

Documents

SHOWING 1 OF 1

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
rad_land_frac_238 radiometer 23.8 GHz antenna gain weighted land fraction in main beam % short 32767 N/A 0.01 N/A
rad_land_frac_340 radiometer 34.0 GHz antenna gain weighted land fraction in main beam % short 32767 N/A 0.01 N/A
rad_liquid_water Should not be used over land. kg/m^2 short 32767 N/A 0.01 N/A
rad_rain_flag See Jason-1 User Handbook. The radiometer rain flag indicates where the radiometer wet troposphere path delay (rad_wet_tropo_corr) is invalid due to rain contamination N/A byte 127 N/A 1 N/A
rad_sea_ice_flag See Jason-1 User Handbook. The radiometer sea ice flag indicates where the radiometer wet troposphere path delay (rad_wet_tropo_corr) is invalid due to sea ice contamination N/A byte 127 N/A 1 N/A
rad_state_flag_oper Side A nominal; Side B redundancy N/A byte 127 N/A 1 N/A
rad_surf_type The radiometer surface type flag is applicable to the radiometer wet troposphere path delays provided by rad_wet_tropo_corr. A value of 0 indicates that open ocean processing is used to compute the path delay, 1 indicates coastal processing is used, and 2 indicates the path delay is invalid due to land N/A byte 127 N/A 1 N/A
rad_water_vapor Should not be used over land. kg/m^2 short 32767 N/A 0.1 N/A
rad_wet_tropo_corr 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 m short 32767 N/A 0.0001 N/A
rain_flag See Jason-1 User Handbook N/A byte 127 N/A 1 N/A
range_20hz_c All instrumental corrections included, i.e. 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. range_20hz_c updated to account for reference plane and internal path delay m float 1.0E+30 N/A 1 N/A
range_20hz_ku All instrumental corrections included, i.e. 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. range_20hz updated to account for reference plane and internal path delay m float 1.0E+30 N/A 1 N/A
range_c All instrumental corrections included, i.e. 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. range_c updated to account for reference plane and internal path delay m float 1.0E+30 N/A 1 N/A
range_ku All instrumental corrections included, i.e. 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. range updated to account for reference plane and internal path delay m float 1.0E+30 N/A 1 N/A
range_numval_c number of valid points for C band range count byte 127 0 to 20 1 N/A
range_numval_ku number of valid points for Ku band range count byte 127 0 to 20 1 N/A
range_rms_c 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 N/A
range_rms_ku 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 m short 32767 N/A 0.0001 N/A
range_used_20hz_c Map of valid points used to compute the 1-Hz C-band altimeter range N/A short 127 N/A 1 N/A
range_used_20hz_ku Map of valid points used to compute the 1-Hz Ku-band altimeter range N/A short 127 N/A 1 N/A
scaling_factor_20hz_c This scaling factor represents the backscatter coefficient for a C-band waveform amplitude equal to 1. It is a raw value accounting for AGC 20Hz correction and internal calibration correction. All other correction are not applied (ie atmospheric attenuation, modeled instrumental errors correction and system bias) dB int 2147483647 N/A 0.01 N/A
scaling_factor_20hz_ku This scaling factor represents the backscatter coefficient for a Ku-band waveform amplitude equal to 1. It is a raw value accounting for AGC 20Hz correction and internal calibration correction. All other correction are not applied (ie atmospheric attenuation, modeled instrumental errors correction and system bias) dB int 2147483647 N/A 0.01 N/A
sea_state_bias_c Computed using wind speed from sigma0 using updated atmospheric attenuation values. 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 Jason-1 User Handbook m short 32767 N/A 0.0001 N/A
sea_state_bias_ku Computed using wind speed from sigma0 using updated atmospheric attenuation values. 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 Jason-1 User Handbook m short 32767 N/A 0.0001 N/A
sig0_20hz_c All instrumental corrections included, excepted the system bias, i.e. AGC instrumental errors correction, internal calibration correction (internal_corr_sig0_c), modeled instrumental errors correction (modeled_instr_corr_sig0_c) and atmospheric attenuation (atmos_corr_sig0_c) dB short 32767 N/A 0.01 N/A
sig0_20hz_ku All instrumental corrections included, excepted the system bias, i.e. AGC instrumental errors correction, internal calibration correction (internal_corr_sig0_ku), modeled instrumental errors correction (modeled_instr_corr_sig0_ku) and atmospheric attenuation (atmos_corr_sig0_ku) dB short 32767 N/A 0.01 N/A
sig0_c All instrumental corrections included, excepted the system bias, i.e. AGC instrumental errors correction, internal calibration correction (internal_corr_sig0_c), modeled instrumental errors correction (modeled_instr_corr_sig0_c) and atmospheric attenuation (atmos_corr_sig0_c) dB short 32767 N/A 0.01 N/A
sig0_ku All instrumental corrections included, excepted the system bias, i.e. AGC instrumental errors correction, internal calibration correction (internal_corr_sig0_ku), modeled instrumental errors correction (modeled_instr_corr_sig0_ku) and atmospheric attenuation (atmos_corr_sig0_ku) dB short 32767 N/A 0.01 N/A
sig0_numval_c number of valid points used to compute C backscatter coefficient count byte 127 0 to 20 1 N/A
sig0_numval_ku number of valid points used to compute Ku backscatter coefficient count byte 127 0 to 20 1 N/A
sig0_rms_c 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 N/A
sig0_rms_ku 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 N/A
sig0_used_20hz_c Map of valid points used to compute the 1-Hz C-band backscatter coefficient N/A byte 127 N/A 1 N/A
sig0_used_20hz_ku Map of valid points used to compute the 1-Hz Ku-band backscatter coefficient N/A byte 127 N/A 1 N/A
solid_earth_tide Calculated using Cartwright and Tayler tables and consisting of the second and third degree constituents. The permanent tide (zero frequency) is not included. See Jason-1 User Handbook m short 32767 N/A 0.0001 N/A
ssha = altitude of satellite (alt) - Ku band corrected altimeter range (range_ku) - altimeter ionospheric correction on Ku band (iono_corr_alt_ku) - model dry tropospheric correction (model_dry_tropo_corr) - radiometer wet tropospheric correction (rad_wet_tropo_corr) - sea state bias correction in Ku band (sea_state_bias_ku) - solid earth tide height (solid_earth_tide) - geocentric ocean tide height solution 1 (ocean_tide_sol1) - geocentric pole tide height (pole_tide) - inverted barometer height correction (inv_bar_corr) - high frequency fluctuations of the sea surface topography (hf_fluctuations_corr for I/GDR off line products only) - mean sea surface (mean_sea_surface). Set to default if the altimeter surface type (surface_type) is set to 1, 2, or 3 (lake_enclosed_sea, ice, or land) m short 32767 N/A 0.001 N/A
surface_type Computed using a DTM2000 file: 0 = open oceans or semi-enclosed seas; 1 = enclosed seas or lakes; 2 = continental ice; 3 = land. See Jason-1 User Handbook N/A byte 127 N/A 1 N/A
surface_type_globcover Computed from a mask built with MODIS and GlobCover data, 0 = Open ocean; 1 = Land; 2 = Continental waters; 3 = Aquatic vegetation; 4 = Continental ice and snow; 5 = Floating ice; 6 = Salted basin. See Jason-1 User Handbook N/A byte 127 N/A 1 N/A
swh_20hz_c All instrumental corrections included, i.e. modeled instrumental errors correction (modeled_instr_corr_swh_c) and system bias m short 32767 N/A 0.001 N/A
swh_20hz_ku All instrumental corrections included, i.e. modeled instrumental errors correction (modeled_instr_corr_swh_ku) and system bias m short 32767 N/A 0.001 N/A
swh_c All instrumental corrections included, i.e. modeled instrumental errors correction (modeled_instr_corr_swh_c) and system bias m short 32767 N/A 0.001 N/A
swh_ku All instrumental corrections included, i.e. modeled instrumental errors correction (modeled_instr_corr_swh_ku) and system bias m short 32767 N/A 0.001 N/A
swh_numval_c number of valid points used to compute C significant waveheight count short 127 0 to 20 1 N/A
swh_numval_ku number of valid points used to compute Ku significant waveheight count short 127 0 to 20 1 N/A
swh_rms_c 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 N/A
swh_rms_ku 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 m short 32767 N/A 0.001 N/A
swh_used_20hz_c Map of valid points used to compute the 1-Hz C-band significant waveheight N/A short 127 N/A 1 N/A
swh_used_20hz_ku Map of valid points used to compute the 1-Hz Ku-band significant waveheight N/A short 127 N/A 1 N/A
ta_187 18.7 GHz antenna temperature K short 32767 N/A 0.01 N/A
ta_238 23.8 GHz antenna temperature K short 32767 N/A 0.01 N/A
You're viewing 150 of 171