Quantifying bed roughness beneath contemporary and palaeo-ice streams

Bed roughness is an important control on ice-stream location and dynamics. The majority of previous bed roughness studies have been based on data derived from radio-echo sounding (RES) transects across Antarctica and Greenland. However, the wide spacing of RES transects means that the links between...

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Bibliographic Details
Published in:Journal of glaciology 2018-10, Vol.64 (247), p.822-834
Main Authors: FALCINI, FRANCESCA A.M., RIPPIN, DAVID M., KRABBENDAM, MAARTEN, SELBY, KATHERINE A.
Format: Article
Language:English
Subjects:
Bathymeters
Bathymetry
Bed roughness
Bedrock
Copyright
Data
Dynamics
Echo sounding
Echoes
Fast Fourier transformations
Flow velocity
Fourier transforms
Geology
geomorphology
Ice
Ice streams
Landforms
Measurement methods
Orientation
Radar
radio-echo sounding
remote sensing
Rivers
Sediments
Streams
Studies
Terrain models
Topography
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Summary:Bed roughness is an important control on ice-stream location and dynamics. The majority of previous bed roughness studies have been based on data derived from radio-echo sounding (RES) transects across Antarctica and Greenland. However, the wide spacing of RES transects means that the links between roughness and flow are poorly constrained. Here, we use Digital Terrain Model/bathymetry data from a well-preserved palaeo-ice stream to investigate basal controls on the behaviour of contemporary ice streams. Artificial transects were set up across the Minch Palaeo-Ice Stream (NW Scotland) to mimic RES flight lines over Institute and Möller Ice Streams (Antarctica). We then explored how different data-resolution, transect orientation and spacing, and different methods, impact roughness measurements. Our results show that fast palaeo-ice flow can occur over a rough, hard bed, not just a smooth, soft bed, as previous work has suggested. Smooth areas of the bed occur over both bedrock and sediment covered regions. Similar trends in bed roughness values were found using Fast Fourier Transform analysis and standard deviation methods. Smoothing of bed roughness results can hide important details. We propose that the typical spacing of RES transects is too wide to capture different landform assemblages and that transect orientation influences bed roughness measurements in both contemporary and palaeo-ice-stream setting.
ISSN:0022-1430
1727-5652
DOI:10.1017/jog.2018.71