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Description

The Sensory Geophysical Data Record (SGDR) files from the Geodetic Mission contain full accuracy altimeter data, with a high precision orbit. 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 will be more suited for your needs.

Product Summary

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

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

Geographic Region
GLOBAL
Coordinate System
CARTESIAN
Granule Spatial Representation
CARTESIAN
Temporal Extent
2012-05-07 to 2013-06-21
Data Partner
Physical Oceanography Distributed Active Archive Center, Jet Propulsion Laboratory, NASA (NASA/JPL/PODAAC)
Concept ID
C2491731831-POCLOUD
Data State
COMPLETE
Number of Files/Granules
10030
Processing Level
2
Published
Updated
Science Keywords
Significant Wave Height ,
Sea Surface 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 Geodetic [Data set]. NASA Physical Oceanography Distributed Active Archive Center. https://doi.org/10.5067/J1GPS-NCG0E 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
agc_c AGC is corrected for instrumental errors due to the imperfections of the on-board attenuators dB short 32767 N/A 0.01
agc_ku AGC is corrected for instrumental errors due to the imperfections of the on-board attenuators dB short 32767 N/A 0.01
agc_numval_c number of valid points used to compute C band AGC count byte 127 0 to 20 1
agc_numval_ku number of valid points used to compute Ku band AGC count byte 127 0 to 20 1
agc_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
agc_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
alt Altitude of satellite above the reference ellipsoid. m float 1.0E+30 N/A 1
alt_20hz Altitude of satellite above reference ellipsoid m float 1.0E+30 N/A 1
alt_echo_type The altimeter echo type is determined by testing the rms of the high rate range measurements against a threshold as well as the number of valid high rate range measurements against a minimum value N/A byte 127 N/A 1
alt_state_flag_band_seq altimeter state flag: Ku/C band sequencing N/A byte 127 N/A 1
alt_state_flag_c_band altimeter state flag: C bandwidth used N/A byte 127 N/A 1
alt_state_flag_c_band_status altimeter state flag: C band status N/A byte 127 N/A 1
alt_state_flag_ku_band_status altimeter state flag: Ku band status N/A byte 127 N/A 1
alt_state_flag_oper Side A = nominal; Side B = redondancy N/A byte 127 N/A 1
atmos_corr_sig0_c atmospheric attenuation correction on C band backscatter coefficient dB short 32767 N/A 0.01
atmos_corr_sig0_ku atmospheric attenuation correction on Ku band backscatter coefficient dB short 32767 N/A 0.01
bathymetry ocean depth/land elevation m int 2147483647 N/A 1
cog_corr Distance antenna-COG correction on altimeter range m short 32767 N/A 0.0001
doppler_corr_c C band Doppler correction on altimeter range m short 32767 N/A 0.0001
doppler_corr_ku Ku band Doppler correction on altimeter range m short 32767 N/A 0.0001
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 Jason-1 User Handbook m int 2147483647 N/A 0.0001
hf_fluctuations_corr Provided as a correction to the inverted barometer correction (inv_bar_corr) m short 32767 N/A 0.0001
hf_fluctuations_corr_era Provided as a correction to the inverted barometer correction from ERA_Interim products (inv_bar_corr_era) m short 32767 N/A 0.0001
ice_flag See Jason-1 User Handbook N/A byte 127 N/A 1
ice_qual_flag_20hz_ku ice retracking quality flag N/A byte 127 N/A 1
ice_range_20hz_c Distance antenna-COG (cog_corr), USO drift correction (uso_corr) and internal path correction (internal_path_delay_corr_c) included m float 1.0E+30 N/A 1
ice_range_20hz_ku Distance antenna-COG (cog_corr), USO drift correction (uso_corr) and internal path correction (internal_path_delay_corr_ku) included m float 1.0E+30 N/A 1
ice_sig0_20hz_c AGC instrumental errors correction and internal calibration correction (internal_corr_sig0_c) included dB short 32767 N/A 0.01
ice_sig0_20hz_ku AGC instrumental errors correction and internal calibration correction (internal_corr_sig0_ku) included dB short 32767 N/A 0.01
internal_corr_sig0_c C band internal calibration correction on backscatter coefficient dB short 32767 N/A 0.01
internal_corr_sig0_ku Ku band internal calibration correction on backscatter coefficient dB short 32767 N/A 0.01
internal_path_delay_corr_c Internal calibration correction on the C-band altimeter range, updated to account for reference plane and internal path delay m int 2147483647 N/A 0.0001
internal_path_delay_corr_ku Internal calibration correction on the Ku-band altimeter range, updated to account for reference plane and internal path delay m int 2147483647 N/A 0.0001
interp_flag_ocean_tide_sol1 0 = valid interpolation; 1 = failure of interpolation i.e. ocean_tide_sol1 set to default value N/A byte 127 N/A 1
interp_flag_ocean_tide_sol2 0 = valid interpolation; 1 = failure of interpolation i.e. ocean_tide_sol2 set to default value N/A byte 127 N/A 1
interp_flag_tb Possible values are: 0 interpolation without gap between JMR data, 1 interpolation with gap between JMR data, 2 extrapolation of JMR data, 3 failure of extrapolation and interpolation N/A byte 127 N/A 1
inv_bar_corr Computed at the altimeter time-tag from the interpolation of 2 meteorological fields that surround the altimeter time-tag. See Jason-1 User Handbook m short 32767 N/A 0.0001
inv_bar_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 meteorological fields that surround the altimeter time-tag. See Jason-1 User Handbook m short 32767 N/A 0.0001
iono_corr_alt_ku 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 Jason-1 User Handbook m short 32767 N/A 0.0001
iono_corr_gim_ku 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 Jason-1 User Handbook m short 32767 N/A 0.0001
lat Positive latitude is North latitude, negative latitude is South latitude. See Jason-1 User Handbook. degrees_north int N/A N/A 1.0E-6
lat_20hz Positive latitude is North latitude, negative latitude is South latitude. See Jason-1 User Handbook degrees_north int 2147483647 N/A 1.0E-6
load_tide_sol1 This value has already been added to the corresponding ocean tide height value recorded in the product (ocean_tide_sol1). See Jason-1 User Handbook m short 32767 N/A 0.0001
load_tide_sol2 This value has already been added to the corresponding ocean tide height value recorded in the product (ocean_tide_sol2). See Jason-1 User Handbook m short 32767 N/A 0.0001
lon East longitude relative to Greenwich meridian. See Jason-1 User Handbook. degrees_east int N/A N/A 1.0E-6
lon_20hz East longitude relative to Greenwich meridian. See Jason-1 User Handbook degrees_east int 2147483647 N/A 1.0E-6
mean_sea_surface The mean sea surface height is referenced to a 20 years mean. See Jason-1 User Handbook. m int 2147483647 N/A 0.0001
mean_sea_surface_err See Jason-1 User Handbook m int 2147483647 N/A 0.0001
mean_topography The mean dynamic topography is referenced to a 20 years mean. See Jason-1 User Handbook. m int 2147483647 N/A 0.0001
mean_topography_err See Jason-1 User Handbook m int 2147483647 N/A 0.0001
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