TY - JOUR

T1 - Optimising ice flow law parameters using borehole deformation measurements and numerical modelling

AU - Chandler, David M.

AU - Hubbard, Bryn

AU - Hubbard, Alun L.

AU - Murray, Tavi

AU - Rippin, David

N1 - Chandler, D. M., Hubbard, B., Hubbard, A., Murray, T., Rippin, D. (2008). Optimising ice flow law parameters using borehole deformation measurements and numerical modelling. Geophysical Research Letters, 35(L12502).

PY - 2008/6/28

Y1 - 2008/6/28

N2 - Internal ice strain rates have been measured along two boreholes drilled through Glacier de Tsanfleuron, Switzerland. Differences between these measurements and the output from a 3D numerical model of glacier motion have been minimized by a scheme that optimizes three rheological parameters in the constitutive equation for ice creep: the stress exponent n, the rate factor A, and a Lower Zone (basal ice) enhancement factor ELZ. Results suggest that a linear rheology dominated by diffusion creep (n = 1) is more appropriate for modelling ice flow in this relatively thin (generally <80 m thick) glacier than the conventional n = 3, and that ELZ is ∼2. For n = 1, the predicted ice crystal size and value of ELZ are both consistent with measurements made on ice cores recovered from the glacier, providing independent support for the optimization technique and the linear creep model.

AB - Internal ice strain rates have been measured along two boreholes drilled through Glacier de Tsanfleuron, Switzerland. Differences between these measurements and the output from a 3D numerical model of glacier motion have been minimized by a scheme that optimizes three rheological parameters in the constitutive equation for ice creep: the stress exponent n, the rate factor A, and a Lower Zone (basal ice) enhancement factor ELZ. Results suggest that a linear rheology dominated by diffusion creep (n = 1) is more appropriate for modelling ice flow in this relatively thin (generally <80 m thick) glacier than the conventional n = 3, and that ELZ is ∼2. For n = 1, the predicted ice crystal size and value of ELZ are both consistent with measurements made on ice cores recovered from the glacier, providing independent support for the optimization technique and the linear creep model.

UR - http://www.scopus.com/inward/record.url?scp=50849133596&partnerID=8YFLogxK

UR - http://hdl.handle.net/2160/6063

U2 - 10.1029/2008GL033801

DO - 10.1029/2008GL033801

M3 - Article

SN - 1944-8007

VL - 35

JO - Geophysical Research Letters

JF - Geophysical Research Letters

IS - 12

M1 - L12502

ER -