In-situquantification of ice rheology and direct measurement of the Raymond Effect at Summit, Greenland using a phase-sensitive radar

Gillet-Chaulet, Fabien, Hindmarsh, Richard C. A., Corr, Hugh F. J., King, Edward C. and Jenkins, Adrian (2011) In-situquantification of ice rheology and direct measurement of the Raymond Effect at Summit, Greenland using a phase-sensitive radar. Geophysical Research Letters, 38 (24). L24503. ISSN 0094-8276

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Official URL: https://doi.org/10.1029/2011GL049843

Abstract

[1] The Glen exponent ncharacterizes the stress‐dependence of ice deformation, directly influencing the rate at which ice masses respond to external forcing. The slow deformation in large ice‐sheets makes laboratory rheometry at representative strain‐rates difficult. We develop a new technique to estimaten in‐situ, deploying a phase‐sensitive radar to measure vertical strain rates of around 10−4 yr−1within the top 1000 m of ice across ice divides at Summit and NEEM, Greenland. A fluid‐dynamical feature, the Raymond Effect, predicts strong vertical strain‐rate variation across divides over distances of a few ice‐thicknesses. We achieve sufficient resolution to show this pattern, enabling us to estimaten= 4.5 by inverting our observations with flow modelling. This is higher than values previously used but consistent with other indirect measurements, implying laboratory measurements do not explore the full range of ice rheology and the consequent possibility of a greater sensitivity and responsiveness in ice‐sheet dynamics.

Item Type: Article
Uncontrolled Keywords: Ice divides, Ice sheet modelling, Ice sheets, Rheology
Subjects: F700 Ocean Sciences
F800 Physical and Terrestrial Geographical and Environmental Sciences
Department: Faculties > Engineering and Environment > Geography and Environmental Sciences
Depositing User: Elena Carlaw
Date Deposited: 27 Apr 2021 13:49
Last Modified: 31 May 2021 14:39
URI: http://nrl.northumbria.ac.uk/id/eprint/46026

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