CPOM Staff based at UCL
Tom Newman
| email: tn |
tel: 0207.679.4406 |
| fax: 0207.679.7883 |
Tom obtained a 1st class M.Sci. with Honours in Earth and Space Science from University College London in 2006. He was awarded the Matthews Prize for Excellence in Geophysics.
His research project is entitled: "Application of synthetic aperture techniques to radar echo soundings of the Pine Island Glacier"
The Pine Island Bay sector of West Antarctica exhibits the largest negative mass balance of the whole of Antarctica. Satellite and airborne altimetry confirm that (PIB) is thinning at a rate of 10cm yr -1 in the interior; increasing to 3-4m yr -1 at the coast. In addition the Pine Island Glacier has accelerated by 38% since 1975; with most of the speed up taking place over the last decade. The arborescent tributary structure of the glacier indicates a complex interconnectivity of ice flow from the coast to the deep interior. This structure allows perturbations initiating at the coast to affect the entire drainage basin more rapidly than if ice flow were more uniform This is especially pertinent as recent data has shown that the northen Pine Island subglacial basin is vulnerable to collapse; which if occurred; could result in a global sea level rise of over 24cm.
The project will make use of data collected during the 2004/05 austral summer season; during which a collaborative US/UK field campaign performed a systematic airborne geophysical survey of the entire Amundsen Sea embayment. The modified De Havilland Twin Otter aircraft which performed the survey were equipped with state of the art geophysics equipment including: Dual-frequency carrier-phase GPS for navigation, Radar altimeter for surface mapping, Wing tipped magnetometers, Gravity meters and a recently developed ice-sounding radar system (PASIN). The PASIN system sounds the whole of the ice sheet thickness utilising two different pulse characteristics: A 0.1-usec pulse optimised for imaging the near surface layering and a 4-usec 10-MHz chirp: to successfully obtain bed-echoes through ice more than 4200m thick. In general the cold and clean Antarctic ice behaves as a low loss dielectric over a wide range of radar frequencies. However within the ice mass there are wide spread internal reflecting horizons; caused principally by variations in ice chemistry. Data obtained from ice cores have revealed that these distinct layers are primarily the result of acid fallout from large volcanoes or large scale variations in global climate. The interpretation of these isochronous surfaces allows for an understanding of glacial flow dynamics throughout the whole ice depth. Features such as crevasses on both the underside and surface may be observed where the flow regime of the glacier changes, such as in proximity to the grounding line.
The research project will be divided into two main sections:
- The development of signal processing software which will use interferometric techniques to resolve layers from within the ice sheet and remove unwanted signal associated with the surface crevasse and other features.
- The interpretation of the processed radar echo soundings over the whole Pine Island Glacier catchment area, with particular attention being paid to the data collected during the five flights over the main trunk and tributaries; which were flown at a constant 150m terrain clearance to optimise the quality of the radar data.
The further development of the processing software and the careful glaciological interpretation of the migrated profiles are critical to gaining a greater understand of the dynamics of Pine Island and the other glaciers of the Amundsen sea embayment.