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Exploring explanations of subglacial bedform sizes using statistical models

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posted on 20.07.2016 by John Hillier, I.A. Kougioumtzoglou, C.R. Stokes, Mike J. Smith, C.D. Clark, M. Spagnolo
Sediments beneath modern ice sheets exert a key control on their flow, but are largely inaccessible except through geophysics or boreholes. In contrast, palaeo-ice sheet beds are accessible, and typically characterised by numerous bedforms. However, the interaction between bedforms and ice flow is poorly constrained and it is not clear how bedform sizes might reflect ice flow conditions. To better understand this link we present a first exploration of a variety of statistical models to explain the size distribution of some common subglacial bedforms (i.e., drumlins, ribbed moraine, MSGL). By considering a range of models, constructed to reflect key aspects of the physical processes, it is possible to infer that the size distributions are most effectively explained when the dynamics of ice-water-sediment interaction associated with bedform growth is fundamentally random. A ‘stochastic instability’ (SI) model, which integrates random bedform growth and shrinking through time with exponential growth, is preferred and is consistent with other observations of palaeo bedforms and geophysical surveys of active ice sheets. Furthermore, we give a proof-of concept demonstration that our statistical approach can bridge the gap between geomorphological observations and physical models, directly linking measurable size frequency parameters to properties of ice sheet flow (e.g., ice velocity). Moreover, statistically developing existing models as proposed allows quantitative predictions to be made about sizes, making the models testable; a first illustration of this is given for a hypothesised repeat geophysical survey of bedforms under active ice. Thus, we further demonstrate the potential of size-frequency distributions of subglacial bedforms to assist the elucidation of subglacial processes and better constrain ice sheet models.

History

School

  • Social Sciences

Department

  • Geography and Environment

Published in

PLoS One

Citation

HILLIER, J.K. ... et al, 2016. Exploring explanations of subglacial bedform sizes using statistical models. PLoS One, http://dx.doi.org/10.1371/journal.pone.0159489

Publisher

Public Library of Science

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VoR (Version of Record)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution 4.0 International (CC BY 4.0) licence. Full details of this licence are available at: http://creativecommons.org/licenses/ by/4.0/

Acceptance date

07/07/2016

Publication date

2016

Notes

This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

ISSN

1932-6203

Language

en

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