N: 66.15 S: -66.15 E: 180 W: -180
Description
The Jason-1 Geophysical Data Records (GDR) Geodetic Mission contain full accuracy altimeter data, with a high precision orbit, provided approximately 35 days after data collection. The data are sorted into cycles that are approximately 11 days long and contain 280 pass files. 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 GDR contain all relevant corrections needed to calculate the sea surface height.
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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 Sort descending | Description | Units | Data Type | Fill Value | Valid Range | Scale Factor | Offset |
|---|---|---|---|---|---|---|---|
| agc_ku | AGC is corrected for instrumental errors due to the imperfections of the on-board attenuators | dB | short | 32767 | N/A | 0.01 | N/A |
| agc_numval_c | number of valid points used to compute C band AGC | count | byte | 127 | 0 to 20 | 1 | N/A |
| alt_state_flag_band_seq | altimeter state flag: Ku/C band sequencing | N/A | byte | 127 | N/A | 1 | N/A |
| alt_state_flag_c_band | altimeter state flag: C bandwidth used | N/A | byte | 127 | N/A | 1 | N/A |
| alt_state_flag_oper | Side A = nominal; Side B = redondancy | N/A | byte | 127 | N/A | 1 | N/A |
| atmos_corr_sig0_c | atmospheric attenuation correction on C band backscatter coefficient | dB | short | 32767 | N/A | 0.01 | N/A |
| 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 | N/A |
| ice_flag | See Jason-1 User Handbook | N/A | byte | 127 | N/A | 1 | N/A |
| ice_qual_flag_20hz_ku | ice retracking quality flag | N/A | byte | 127 | N/A | 1 | N/A |
| ice_sig0_20hz_ku | AGC instrumental errors correction and internal calibration correction (internal_corr_sig0_ku) included | dB | short | 32767 | N/A | 0.01 | N/A |
| 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 | N/A |
| 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 | N/A |
| lon_20hz | East longitude relative to Greenwich meridian. See Jason-1 User Handbook | degrees_east | int | 2147483647 | N/A | 1.0E-6 | N/A |
| 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 | 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 |
| 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_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_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 |
| 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_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 |
| 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_swh_c | quality flag for 1 Hz altimeter data: C band SWH | 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_swh_ku | quality flag for 1 Hz instrumental correction: Ku band SWH | 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 |
| 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 |
| rain_flag | See Jason-1 User Handbook | N/A | byte | 127 | 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_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 |
| 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 |
| 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_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 |
| 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_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_ku | number of valid points used to compute Ku significant waveheight | count | short | 127 | 0 to 20 | 1 | 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_ku | Map of valid points used to compute the 1-Hz Ku-band significant waveheight | N/A | short | 127 | N/A | 1 | N/A |
| tb_187_smoothed | Brightness temperatures are along-track averaged | K | short | 32767 | N/A | 0.01 | N/A |