N: 66.15 S: -66.15 E: 180 W: -180
Description
Provides L1B high resolution (HR) short time critical (STC; 36-hour latency) altimetry data from the Poseidon-4 SAR altimeter on the Sentinel-6A Michael Freilich spacecraft which include the geolocated, fully SAR processed and calibrated multi-looked HR Ku-band waveforms. The S6A STC product is analogous to the Jason-3 IGDR product.
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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 |
|---|---|---|---|---|---|---|---|
| /data_20/ku/tm_cor2 | The COR2 (altitude rate estimation) value, copied from ISP. The altimeter estimates one COR2 value per radar cycle. It is used in combination with the H0 to compute the CAI and FAI instructions. NOTE: T0 = 1/altimeter_clock_ku. The COR2 closest in time is used. | T0/16/64 | int | -2147483647 | N/A | 1 | N/A |
| /data_20/ku/tm_h0 | The H0 (initial altitude instruction) value, copied from ISP. The altimeter provides one H0 value per radar cycle. It is used in combination with the COR2 to compute the CAI and FAI instructions. NOTE: T0 = 1/altimeter_clock_ku. The closest H0 in time is used. | T0/64 | int | -2147483647 | N/A | 1 | N/A |
| /data_20/ku/tm_source_sequence_counter | This is the instrument record counter, copied from ISP. | 1 | short | -32767 | N/A | 1 | N/A |
| /data_20/ku/tracker_range_calibrated | This is the 1-way distance from the satellite's center of mass to the middle of the range window (sample ns/2 from 0). It includes the following range calibrations: (a) range_corr_internal_delay_cal, (b) range_corr_internal_delay_diff, (c) range_corr_external_group_delay, (d) range_corr_com. Note: the actual altimeter clock (variable 'altimeter_clock_ku') has been used to compute the altimeter range | m | int | -2147483647 | N/A | 0.0001 | 1300000 |
| /data_20/ku/tracker_range_calibrated_diode | This is the 1-way distance from the satellite's center of mass to the middle of the range window as given by the DIODE+DEM (sample ns/2 from 0). It includes the following range calibrations: (a) range_corr_internal_delay_cal, (b) range_corr_internal_delay_diff, (c) range_corr_external_group_delay, (d) range_corr_com. Note: the actual altimeter clock (variable 'altimeter_clock_ku') has been used to compute the altimeter range | m | int | -2147483647 | N/A | 0.0001 | 1300000 |
| /data_20/ku/variable_digital_gain | Variable component of the gain produced by the digital processing unit. The variable gain closest in time is used. | dB | short | -32767 | N/A | 0.01 | N/A |
| /data_20/ku/velocity_vector | velocity vector at the center of mass in ITRF. The 3 components are given according to the 'space_3d' dimension: [1] x, [2] y, [3] z | m/s | int | -2147483647 | N/A | 0.0001 | N/A |
| /global/ku/antenna_gain | Maximum antenna gain from on-ground characterization. | dB | int | -2147483647 | N/A | 1.0E-6 | N/A |
| /global/ku/burst_phase_array_cor | Burst phase correction applied to the SAR Ku waveforms. It is obtained by averaging the burst phase along a configurable time window to reduce noise. The closest burst phase correction in time is used. | rad | int | -2147483647 | N/A | 1.0E-6 | N/A |
| /global/ku/burst_power_array_cor | Burst power correction applied to the SAR Ku waveforms. It is obtained by averaging the burst power along a configurable time window to reduce noise. The closest burst power in time is used. | dB | int | -2147483647 | N/A | 1.0E-6 | N/A |
| /global/ku/cal2_correction | CAL2 to be applied to the science data. It is obtained by normalizing and inverting the average CAL2 waveform. The closest CAL2 in time is used. | 1 | double | N/A | N/A | 1 | N/A |
| /global/ku/g_scaling | Ratio of losses between the RA transmission/reception and calibration paths from on-ground characterization | dB | int | -2147483647 | N/A | 1.0E-6 | N/A |
| /global/ku/hr_processing_configuration_flags | remove_doppler_ambiguities (0 - not removed, 1 - removed), azimuth_weighing_applied (0 - not applied, 1 - applied), antenna_weighting_applied (0 - not applied, 1 - applied), surface_weighting_applied (0 - not applied, 1 - applied), avoid_zeros_in_multilooking (0 - not avoided, 1 - avoided), exact_azimuth_processing (0 - approximate method, 1 - exact method) | N/A | byte | -1 | 0 to 63 | 1 | N/A |
| /global/ku/processing_configuration_flags | uso_correction_activated (0 - deactivated, 1 - activated), cal1_correction_activated (0 - deactivated, 1 - activated), cal1_power_correction_max (0 - total power, 1 - maximum power), cal2_correction_activated (0 - deactivated, 1 - activated), cal1_delay_correction_max (0 - cog , 1 - max power) | N/A | byte | -1 | 0 to 31 | 1 | N/A |
| /global/ku/range_cor_external_group_delay | The absolute 1-way group delay contribution for parts outside the calibration loop | m | int | -2147483647 | N/A | 0.0001 | N/A |
| /global/ku/range_oversampling_factor | The instrument samples the waveforms with a 395 MHz clock, providing a nominal_sampling = c / 395e6 / 2 = ~0.379m (with c=speed of light). In addition, the ground processor can apply an oversampling factor, providing a waveform_sampling = nominal_sampling / range_oversampling_factor. Note that the altimeter range resolution is fixed and given by the chirp bandwidth of 320 MHz: c / 320e6 / 2 = ~0.468m | 1 | byte | -128 | N/A | 1 | N/A |
| /global/ku/residual_fixed_digital_gain_raw | This variable accounts for any potential residual gain to be applied to the HR RAW waveform. | dB | int | -2147483647 | N/A | 1.0E-6 | N/A |
| /global/ku/residual_fixed_digital_gain_rmc | This variable accounts for any potential residual gain to be applied to the HR RMC waveform. | dB | int | -2147483647 | N/A | 1.0E-6 | N/A |
| looks | Counter to index the looks within a stack (from 0 to 447) | 1 | short | N/A | N/A | 1 | N/A |
| pulses | Counter to index the pulses within a burst (from 0 to 63) | 1 | byte | N/A | N/A | 1 | N/A |
| samples | Counter to index the waveform samples (from 0 to 255) | 1 | short | N/A | N/A | 1 | N/A |
| samples_ov | Counter to index the waveform samples after oversampling (from 0 to 511) | 1 | short | N/A | N/A | 1 | N/A |
| space_3d | Counter to index the cartesean coordinates (from 1 to 3) | 1 | byte | N/A | N/A | 1 | N/A |