Processed bed elevation picks from airborne radar depth sounding across the Evans Ice Stream, Southern Palmer Land (1994/95 season)
The survey collected a total of 11,500 km of data along 22 lines, spaced 12 km apart and oriented perpendicular to the strike of both the Bouguer anomaly field, as derived from land data (McGibbon and Smith, 1991), and the major sub-ice topographical features (Doake et al., 1983). The speed of the a...
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| Format: | Dataset |
| Language: | English |
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UK Polar Data Centre, Natural Environment Research Council, UK Research & Innovation
2020
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| Online Access: | https://dx.doi.org/10.5285/2c261013-9a0e-447d-a5bb-b506610b14ff https://data.bas.ac.uk/full-record.php?id=GB/NERC/BAS/PDC/01347 |
| Summary: | The survey collected a total of 11,500 km of data along 22 lines, spaced 12 km apart and oriented perpendicular to the strike of both the Bouguer anomaly field, as derived from land data (McGibbon and Smith, 1991), and the major sub-ice topographical features (Doake et al., 1983). The speed of the aircraft was set to produce a sample spacing of about 60 m and the data were collected at heights between 1600 and 2000 m above sea level. The gravity signal was recorded using a LaCoste and Romberg air/sea gravimeter, S-83, which has been kindly loaned to BAS by the Hydrographic Office of the Royal Navy. The meter was modified by the ZLS company for use in an aircraft. The equipment was deployed in a BAS De-Havilland Twin Otter aircraft. Differential, dual frequency, carrier phase, GPS measurements of the aircraft's motion were made using Trimble and Ashtech geodetic receivers and antennas. Ice thickness data were obtained using a BAS-built, radio echo sounding system (Corr and Popple, 1994). Ice-bottom returns over most of the survey area were obtained at a sample spacing of approximately 28 m. GPS measurements were tied into base stations in International Terrain Reference Frame network (Dietrich et al., 1998) and gravity measurements to base stations in the IGSN71 net (Jones and Ferris, 1999). We present here the processed bed elevation picks from airborne radar depth sounding collected using the BAS PASIN radar system. Data are provided as XYZ ASCII line data. : Data provided here includes picked ice sheet bed elevation along main line sections of the survey grid. Ice thickness data were obtained using a BAS-built, radio echo sounding system (Corr and Popple, 1994). No data from turns is included. Note that one example of overlapping, or close proximity flight lines exists and contrasting bed elevation data exists on tow line segments. Bed elevation data on L541 was deemed inaccurate and is excluded from gridding Channel description: Basic Channels Name Description Lon Longitude WGS 1984 Lat Latitude WGS 1984 x x projected meters* y y projected meters* Radar surfElev Surface elevation. BEDMAP2 surface used here. bedElev Ice bed elevation, derived by subtracting tice from surfElev tIce Ice thickness. *Projected coordinates (x and y) are in Polar sterographic defined as follows: Latitude of natural origin: -71 Longitude of natural origin: 0 Scale factor at natural origin: 0.994 False easting 0 False northing 2082760.109 Positioning for the Evans ice stream survey uses kinematic differential GPS. Processing was carried out using GPSurvey software. Differential positioning used fixed base stations at each of the operational camps (Jones et al., 2002). Positions are calculated for the phase centre of the aircraft antenna. All positions (Lat, lon and height) are referred to the WGS1984 ellipsoid. |
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