Airborne radio-echo sounding of the English Coast, western Palmer Land, Antarctic Peninsula (2016/17 season)
This dataset includes ~3,000 line km of radio-echo sounding data along the English Coast of western Palmer Land in the Antarctic Peninsula. Data was acquired by the British Antarctic Survey Polarimetric-radar Airborne Science Instrument (PASIN2) ice sounding radar system in the austral summer of 201...
| Main Authors: | , |
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| Format: | Dataset |
| Language: | English |
| Published: |
UK Polar Data Centre, Natural Environment Research Council, UK Research & Innovation
2020
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| Subjects: | |
| Online Access: | https://dx.doi.org/10.5285/e07d62bf-d58c-4187-a019-59be998939cc https://data.bas.ac.uk/full-record.php?id=GB/NERC/BAS/PDC/01339 |
| Summary: | This dataset includes ~3,000 line km of radio-echo sounding data along the English Coast of western Palmer Land in the Antarctic Peninsula. Data was acquired by the British Antarctic Survey Polarimetric-radar Airborne Science Instrument (PASIN2) ice sounding radar system in the austral summer of 2016/2017. Radar lines collected at ~3-5 km line spacing transect a number of outlet glacier flows, close to the grounding line, where continental ice begins to float. Data were funded by a BAS National Capability grant. : The British Antarctic Survey Polarimetric-radar Airborne Science Instrument (PASIN2) ice sounding radar system operates at a frequency of 150 MHz, using a pulse-coded waveform at an effective acquisition rate of 312.5 Hz and a bandwidth of 13 MHz. Radio-echo sounding data were collected at an average flying velocity of 55 m s-1. Along-track processing of the data results in an output data rate of 5 Hz, which produces an average spacing between radar traces of 11 m. Range compressed data were processed using unfocused SAR. The ice/bed reflector was determined in PROMAX software, where the first-break picker tool was used to automatically determine the onset of the bed reflector. These picks were then manually assessed and corrected where necessary. An electromagnetic wave propagation speed in ice of 0.168 m ns-1 and a constant firn correction of 10 m were used for topographic correction. Ice thickness was calculated by subtracting surface elevation measurements (derived from radar/laser altimeters for aircraft terrain clearance) from bed reflector depth picks. Data description: The data is composed of three folders: - 4microseconds: Contains data designed to image the bed. Pulse length of 4 microseconds - 1microsecond: Contains data designed to enhance imaging of internal layers Pulse length of 1 microsecond Data for 4us and 1us are composed of both SEGY and TXT files. Column desciption of txt file: 1.traceNum, this is the SEGY trace number 2. PriNum, radar shot number 3. Time, in format YYYYMMDD T hhmmss.ddd 4. dateNum, in a convenient Matlab format 5. radSeg, radar file segment (20 second length) Name descriptions for segy are based on the original archive file names, so: fXXy_TxP1234_Rx1234_L4_ns1536_skip25_DBS5Hz fXXy_TxP1234_RxB_L1_C_ns1536_skip25_DBS5Hz fXX = flight number y = radar radar start/restart value i.e. a=1 continuous run, b=1 restart, 2=second restart etc. this is more a through back to old incarnations of pasin that used tapes and spinning disk that sometime caused the system to stop/freeze due write errors etc. we still include as it is useful for calibration flights are flights with varied setups. TxP1234=is which antennas did the transmitting [P=port, S=starboard, B=belly plus antenna numbers] Rx1234= is which antennas did the receiving [P=port, S=starboard, B=belly, plus antenna numbers, no number represents combining of antenna array] Lx=Length of transmit chirp i.e. 1us or 4us C=combined (if used) this is an addition from the raw data naming convention. ns1536=number of samples per trace during processing. (pri =64us, fs=24MHz) skip25=basically the decimation value when processing DBS5Hz=final presented data frequency i.e. 5Hz Navigation information is not held in the segy file header and can be derived from the bed pick files using traceNum or PriNum as a key to link the two datasets - Bed picks: Contains bed picks data. Channel description: 1.traceNum, this is the SEGY trace number 2. Lon, Longitude 3. Lat, Latitude 4. Time, in format YYYYMMDD T hhmmss.ddd 5. dateNum, in a convenient Matlab format 6. PriNum, radar shot number 7. Eht, height of aircraft above WGS84 ellipsoid (m) 8. terrainClear, height of aircraft above the terrain (m) 9. surfElev, height of ice surface above above WGS84 ellipsoid (m) 10. surfSource, source of elevation measurements 0 = lidar, 1 = interpolated lidar for gaps ~ 55 m, 2 = from ice sounding radar 11. bedElev, height of ice bed above above WGS84 ellipsoid (m). Derived from surface minus ice thickness 12. iceThick, ice thickness (m) 168 metres/microsecond was used and 10 metres added for firn. 13. surfPickEff, the ice surface sample for the onset of the surface return 14. botPickLoc, the sample location for the onset of the bed return 15. sampOffset, the fiducal or zero radar range-sample : Sample collection: British Antarctic Survey Polarimetric-radar Airborne Science Instrument (PASIN2) ice sounding radar system Processing: PROMAX |
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