Abstract:
This data set corresponds to the processing of data acquired by the British Antarctic Survey (BAS) airborne Synthetic Aperture Radar (SAR) PASIN2 (Polarimetric Airborne Scientific INstrument, mark 2), designed for deep ice sounding and basal 3D-mapping. The dataset includes the processed calibration data collected over the sea surface near Rothera Research Station during the Antarctic Summers campaigns in 2016/17 FISS (Filchner Ice Shelf System) and 2019/20 BEAMISH (Bed Access, Monitoring and Ice Sheet History) projects, and the processed SAR images as depth profiles in the Recovery Ice Stream near its grounding line, in 2016/17 (FISS). With multiple antennas for transmission and reception at 150-MHz central frequency, and an across-track physical array, PASIN2 resolves the ambiguities for distinguishing between scatterers from port and starboard directions. After processing several 2D SAR images (range and along-track dimensions) with transmitter-receiver pairs, the directional ambiguities are resolved, obtaining the across-track Direction of Arrival (DoA, elevation angle) estimation. Finally, from the 3D geometry of range, along-track and across-track angle, the real depths and across-track distances are estimated, regarding the case of the incorrectly assumed vertical DoA of a single SAR image. The calibration flights assessed and validated the instrument antenna patterns and processing performances. In this dataset, only the simulated and measured antenna patterns, and SAR and DoA images are included. By resolving directional ambiguities and accounting for reflector across-track location, the true ice thickness and bed elevation are obtained, thereby removing the error of the usual assumption of vertical DoA, that greatly influence the output of flow models of ice dynamics.
This work was supported by NERC grant reference NE/L013444/1.
Keywords:
Antarctica, Recovery Ice Stream, aerogeophysics, ice thickness, synthetic aperture radar
Arenas Pingarron, A., Corr, H., Jordan, T., Robinson, C., Nicholls, K., & Smith, A. (2023). Airborne synthetic aperture radar ice-sounding depth profiles from Recovery Ice Stream 2016/17, and calibration data from Rothera 2016/17 and 2019/20 (Version 1.0) [Data set]. NERC EDS UK Polar Data Centre. https://doi.org/10.5285/faac4156-047d-47ba-9e31-1a4f766bfdf8
| Access Constraints: | No restrictions apply. |
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| Use Constraints: | Data supplied under Open Government Licence v3.0 http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/. |
| Creation Date: | 2023-01-18 |
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| Dataset Progress: | Complete |
| Dataset Language: | English |
| ISO Topic Categories: |
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| Parameters: |
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| Personnel: | |
| Name | UK Polar Data Centre |
| Role(s) | Metadata Author |
| Organisation | British Antarctic Survey |
| Name | Alvaro Arenas Pingarron |
| Role(s) | Investigator, Technical Contact |
| Organisation | British Antarctic Survey |
| Name | Hugh Corr |
| Role(s) | Investigator |
| Organisation | British Antarctic Survey |
| Name | Tom Jordan |
| Role(s) | Investigator |
| Organisation | British Antarctic Survey |
| Name | Carl Robinson |
| Role(s) | Investigator |
| Organisation | British Antarctic Survey |
| Name | Keith Nicholls |
| Role(s) | Investigator |
| Organisation | British Antarctic Survey |
| Name | Andrew Smith |
| Role(s) | Investigator |
| Organisation | British Antarctic Survey |
| Parent Dataset: | N/A |
| Reference: | Arenas-Pingarrón, Á., et al.: Polarimetric airborne scientific instrument, mark 2, an ice-sounding airborne synthetic aperture radar for subglacial 3D imagery. IET Radar Sonar Navig. 1-14 (2023). https://doi.org/10.1049/rsn2.12428 Frémand, A. C., Bodart, J. A., Jordan, T. A., Ferraccioli, F., Robinson, C., Corr, H. F. J., Peat, H. J., Bingham, R. G., and Vaughan, D. G.: British Antarctic Survey's aerogeophysical data: releasing 25 years of airborne gravity, magnetic, and radar datasets over Antarctica, Earth Syst. Sci. Data, 14, 3379-3410, https://doi.org/10.5194/essd-14-3379-2022, 2022. |
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| Quality: | The amplitude and relative phase of the antenna patterns in transmission (as an array of 4 antennas) and reception (as 12 single and independent antennas), were assessed with calibration flights above the sea surface. The patterns are assumed as invariant along each session, if the antenna configuration remains. Direction of Arrival (DoA) estimation algorithms were evaluated with calibration flights. The transmitted radar pulses are not calibrated, as parameter drifts are not expected to affect the quality. In the receiver units, during each flight there is a drift in the recording, causing a delay and phase drift in the sampled data, which is corrected when combining the several SAR images to process a single Direction of Arrival (DoA) image. |
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| Lineage: | The raw data was collected by the airborne Synthetic Aperture Radar (SAR) PASIN2. It is 150-MHz coherent pulsed radar, transmitting chirped pulses with linear frequency sweep, with 13 MHz bandwidth and effective pulse repetition frequency 125 Hz. On board of a De Havilland DHC-6 Twin Otter aircraft, in ice-sounding flights the nominal speed is 60 m/s, and the terrain clearance (height above closest surface) is 300 m. PASIN2 has 12 antenna elements: 8 underwing folded-dipoles switching between transmit (TX) and receive (RX) modes, and 4 printed-dipoles being RX-only attached to the fuselage belly. The data processing is performed off-line, consisting of: 1) channel calibration; 2) 2D SAR imaging, based on pulse-compression for range dimension, and back-projection for along-track dimension; 3) Direction of Arrival estimation (DoA) of the remaining across-track angle, based on the non-linear MUSIC (Multiple Signal Classification) algorithm, by using several SAR images from different transmitters or receivers; and 4) 3D-mapping from the three dimensions of range, along-track and across-track angle, by correcting the real depths and across-track distances, regarding the case of incorrectly assumed vertical DoA of a single SAR image. In this dataset are included: the SAR and DoA images from nominal surveying flights above the Recovery Glacier; and calibration data and the measured antenna patterns, from calibration flights above the sea surface near Rothera Research Station. | |
| Temporal Coverage: | |
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| Start Date | 2019-12-31 |
| End Date | 2019-12-31 |
| Start Date | 2016-12-21 |
| End Date | 2017-01-23 |
| Spatial Coverage: | |
| Latitude | |
| Southernmost | -81.2999 |
| Northernmost | -80.7694 |
| Longitude | |
| Westernmost | -37.3489 |
| Easternmost | -36.5203 |
| Altitude | |
| Min Altitude | 392.2291 m |
| Max Altitude | 846.4242 m |
| Depth | |
| Min Depth | -180.0 m |
| Max Depth | 2995.2 m |
| Latitude | |
| Southernmost | -68.248 |
| Northernmost | -67.816 |
| Longitude | |
| Westernmost | -67.74 |
| Easternmost | -67.418 |
| Altitude | |
| Min Altitude | 758 m |
| Max Altitude | 1535 m |
| Depth | |
| Min Depth | N/A |
| Max Depth | N/A |
| Data Resolution: | |
| Latitude Resolution | N/A |
| Longitude Resolution | N/A |
| Horizontal Resolution Range | 1 meter - < 30 meters |
| Vertical Resolution | 6.48 m |
| Vertical Resolution Range | 1 meter - < 10 meters |
| Temporal Resolution | 16 ms |
| Temporal Resolution Range | < 1 second |
| Location: | |
| Location | Antarctica |
| Detailed Location | Filchner Ice Shelf, Recovery Glacier |
| Location | Antarctica |
| Detailed Location | Adelaide Island, Rothera Research Station |
| Sensor(s): |
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| Data Collection: | PASIN2 (Polarimetric Airborne Scientific INstrument, mark 2) radar; Matlab R2020b software. The parameter files used for processing, and a script for generating the plots with antenna patterns, are in the open repository https://github.com/antarctica/calibration-processing-parameters-PASIN2.git. |
| Distribution: | |
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| Distribution Media | Online Internet (HTTP) |
| Distribution Size | 682 MB |
| Distribution Format | netCDF |
| Fees | N/A |
| Distribution Media | Online Internet (HTTP) |
| Distribution Size | 286 kB |
| Distribution Format | ASCII |
| Fees | N/A |
| Distribution Media | Online Internet (HTTP) |
| Distribution Size | 2.1 MB |
| Distribution Format | TIFF |
| Fees | N/A |
| Data Storage: | Data structure and directory trees in: * Antenna_patterns/Readme.txt * BEAMISH_1920/Readme_BEAMISH_1920_content.txt * FISS_1617/Readme_FISS_1617_content.txt Open formats: * image files ('.tif'), with plots of the calibration results; * netCDF files ('.nc'), with processed data and calibration data; * text files ('.txt'), with log-diary files. SAR images (folders FISS_1617/Model_DiffractionRefraction(DR) and FISS_1617/Model_ PureRefraction(PR)): * Depth profiles: netCDF files, with extension '.nc', and keyword 'SAR' in the file name. The complex-domain SAR image is stored with its real and imaginary parts, respectively in the two-dimensional (joint depth and along-track) variables "SARimageReal" and "SARimageImag". The depth is in the variable "radialDepthGrid", and the along-track indexin the variable "profile". * Log-diary files: text files. * The corresponding processing-parameter file are in the public repository https://github.com/antarctica/calibration-processing-parameters-PASIN2/tree/main/FISS_1617, as Matlab text file with extension '.m'. DoA images (folders FISS_1617/Model_DiffractionRefraction(DR) and FISS_1617/Model_ PureRefraction(PR)): * Depth profiles: netCDF files, with extension '.nc', and keyword 'DoA' in the file name. The DoA image is represented by the 3-dimensional variable "directionOfArrival", being the third dimension the number of estimated directions (1 or 2) at each of the two-dimensional coordinates of joint depth and along-track. For 1 estimated direction, the keyword of the file name is '1DoA', and for 2 directions '2DoA'. The depth is in the variable "radialDepthGrid", and the along-track indexin the variable "profile". * Log-diary files: text files. * The corresponding processing-parameter file are in the public repository https://github.com/antarctica/calibration-processing-parameters-PASIN2/tree/main/FISS_1617, as Matlab text file with extension '.m'. Season calibration data (folders FISS_1617/SeasonCalibration and BEAMISH_1920/SeasonCalibration): * netCDF files, with extension '.nc', and keywords 'calConstantAPD' or 'calVaryingRollPitchAP' in the file name. Flight calibration data (folder FISS_1617/FlightCalibration): * netCDF files, with extension '.nc', and keyword 'calibration_PulsePhase' in the file name. Antenna patterns (folder Antenna_patterns): * Simulated antenna patterns, in text files ('.txt') with names 'PortPattern.txt' and 'StarboardPattern.txt'; * Images ('.tif') with plots representing the calibration data. * The script to generate plots with the antenna patterns is in the public repository https://github.com/antarctica/calibration-processing-parameters-PASIN2/tree/main/Antenna_patterns, as a Matlab script with extension '.m'. |