This database provides access to internal layers digitised from airborne radio-echo sounding (RES) surveys conducted across the Antarctic Ice Sheet by a consortium of the UK Scott Polar Research Institute, US National Science Foundation and the Technical University of Denmark between 1974 and 1979. The internal layers at the time of surveying were only recorded onto film. In 2004 the original film records were scanned into a digital database, and from 2004-2006 'digitised' internal layers were retrieved from the new electronic records. The database contains digitised internal layers from the original analogue records, as well as 3-dimensional visualisations of the internal layers overlaid over Antarctic subglacial topography (BEDMAP).
The RES surveys conducted by this SPRI-NSF-TUD consortium took in approximately 400,000 km of flight track across both the West and East Antarctic Ice Sheets. Covering ~70% of the ice sheet overall. The surveys were driven principally by a desire to measure ice thickness, but also captured numerous internal layers existing through most of the depth profile across large swathes of the ice sheet.
Compilation of the database was sponsored by the NERC Centre for Polar Observation and Modelling, and the data is hosted by NERC/British Antarctic Survey.
Antarctic ice-sheet, RES, ice thickness, ice-sheet, radio-echo sounding
|Dataset Progress:||In Work|
|ISO Topic Categories:||
|Role(s)||Technical Contact, Investigator|
|Organisation||British Antarctic Survey|
|Organisation||British Antarctic Survey|
|Lineage:||In 2004, as part of a NERC Centre for Polar Observation and Modelling (CPOM) initiative led by Professor Martin Siegert, then based in the Bristol Glaciology Centre, photographic copies of the raw 35 mm film records were scanned, and each scan was reformatted to form a single electronic copy of a RES transect (i.e. a ''jpeg' or 'tiff' file). Each transect was loaded into an image analysis package (i.e. ERDAS ImagineTM) in which internal layers were traced. The traced layers, in addition to the ice surface and bed, were then digitised at each navigational control point. The resulting dataset was then standardised with respect to the ice surface, such that the data relate to depths below the surface of the ice sheet. A CPOM follow-up to this work, conducted between 2005 and 2006 by Dr. Robert Bingham, then also based at the Bristol Glaciology Centre, was concerned with emplacing these data into a 3-D environment. This website provides a repository for both the 2-D traced internal layers and their visualisations within a 3-D environment.|
|Detailed Location||West Antarctic Ice Sheet|
|Detailed Location||East Antarctic Ice Sheet|
|Data Collection:||RES data were collected using a 60 MHz system with a 250 ns pulse length. Navigation proceeded through the use of an inertial aircraft system, and although not as accurate as that which can be achieved using modern GPS, navigational accuracy was typically attained to within 1 km, an acceptable resolution for most ice-sheet modelling applications. Because the survey programme preceded the 'digital age', data recording was analogue only. Data were recorded onto 35 mm photographic film as 'Z-scope' 'radargrams', in which single RES pulses are stacked next to one another in a time-dependent manner, and navigational tick-marks added to these records enabled tying-in of the records with geographical waypoints. These data represent pseudo-cross-sections of the ice sheet from which internal layers can be viewed, traced and extracted. Nevertheless, prior to 2004, the analogue records pertaining to internal layers remained largely unused in glaciological applications: this was primarily because the data were not in digital form thus it was difficult and time-consuming to extract information relevant to modelling.|
|Distribution Media||Online Internet (HTTP)|
|Data Storage:||Data are available in Excel Spreadsheets, and 3D Z-Scopes which must be viewed using IVS FledermausTM or IVS iView3DTM freeware|
|Access Constraints:||No restrictions apply.|
|Use Constraints:||Data released under Open Government Licence V3.0 : http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/|