Bingham et al 2010 (1 &2) Flashcards
What does this paper research>
Focusing on the West Antarctic Ice Sheet, we review progress to date in achieving this goal, and the use of radar and seismic imaging to assess:
(1) subglacial bed morphology and roughness;
(2) subglacial bed reflectivity; and
(3) subglacial sediment properties.
What future challenges in glacial geomorphology does the paper identify?
(1) embracing numerical modelling as a framework for testing hypotheses of glacial landform and landscape development;
(2) identifying analogues beneath modern ice sheets for landscapes and landforms observed across deglaciated terrains;
(3) repeat-surveying dynamic subglacial landforms to assess scales of formation and evolution; and
(4) applying glacial geomorphological expertise more fully to extraterrestrial cryospheres.
What is glacial geomorphology defined as?
The landforms, sediments and landscapes created and/ or modified by glaciation, and the study of these features and their formative processes.
How has remote sensing and numerical modelling enabled glacial geomorphologists increasingly to engage with elucidating glaciation over far larger spatial and temporal timescales than was previously possible>
Remote sensing, especially from space, has allowed glacial landscapes clearly to be observed over far greater spatial scales than before.
Numerical modelling has enabled hypothesis-testing over the correspondingly larger timescales required to understand the development and evolution of these spatially vast landscapes.
The development of a suite of ‘Earth observation’ satellites, such as SPOT5 and ASTER, has enabled us, for the first time, to do what?
To image landscapes effectively at up to continental scales (eg, Clark, 1997; Smith et al., 2005).
Illustrating the profound effect that remote sensing has had on scales of analysis means that…
Satellites have clearly imaged large-scale landforms (eg, megascale glacial lineations; Clark, 1993) that previously went unrecognized because they appear too fragmented on the smaller scales of aerial photographs of field investigation.
Perhaps more than any other factor, such imagery has strengthened our appre- ciation that…
large parts of the Earth’s terrestrial landscape have fundamentally been shaped by the growth and decay of major ice sheets; and the consequent ability to synthesize previously disparate observations of landforms and local- scale models, and upscale to continental-scale models of (de)glaciation, has fuelled a shift away from the more traditional smaller-scale ‘alpine glaciation’ studies towards those with a larger-scale ‘ice-sheet-glaciation’ emphasis.
A particularly dynamic growth area of glacial geomorphology now concerns the identification of…
‘Palaeo-ice streams’ across deglaciated terrain.
exposed subglacial landforms and sediments impart vital clues concerning what has controlled the flow, and changes in flow, of former ice streams and glaciers. Understanding these controls is vital, as satellite-derived ice- velocity observations have demonstrated that arterial fast-flowing ice streams account for the vast majority of overall ice flux in modern ice sheets
How much does the West Antarctic Ice Sheet (WAIS) hold in sea level rise equivalent?
3.3 m of sea-level rise (Bamber et al., 2009)
What has motivated research into the fundamental controls on ice- stream behaviour in West Antarctica since the early 1970s?
Satellite observations of its highly dynamic behaviour, comprising dramatic thinning and ice-acceleration in some parts.
The WAIS is drained predominantly by three catchments…
The Ross catchment drains ice westwards across the Siple Coast to the Ross Ice Shelf via a series of ice streams.
The Ronne catchment feeds ice to the Filchner-Ronne Ice Shelf.
Ice flow from the Amundsen catchment is unprotected by a large ice shelf,
and is routed predominantly via Pine Island and Thwaites Glaciers.
A key question for the geomorphologist, therefore, is: what parameters extracted by radar across modern ice sheets are useful in helping to interpret formerly glaciated landscapes? To date, the answer may be divided into two categories
(1) subglacial topography itself, specifically addressed by ana- lysing bed roughness along radar survey tracks; and (2) radar-derived bed-compositional proper- ties, a proxy for which is the strength of the radar-returned power, or bed reflectivity.
Bed roughness can be defined qualitatively as
The vertical variation of an ice-sheet bed with horizontal distance.
