012-agu2021.txt (2031B)
1 Below is my recorded talk for the [1]American Geophysical Union 2021 Fall 2 Meeting. Full abstract: 3 4 Title: Process-based modeling of glacial till advection 5 6 Anders Damsgaard(1), Jan A. Piotrowski(1), Ian Madden(2), Jenny Suckale(2), 7 Kenny K. Sørensen(3) 8 9 1: Department of Geoscience, Aarhus University, Denmark 10 2: Department of Geophysics, Stanford University, CA, USA 11 3: Department of Civil and Architectural Engineering, Aarhus University, 12 Denmark 13 14 Glacial flow can reshape the Earth surface through erosion and deposition. 15 Many past and present ice sheets lie on soft beds, and till mobilization 16 and transport is governed by the degree of basal coupling, fluctuations in 17 thermal state, subglacial hydrology, and the mechanics of the basal till 18 itself. Changes in basal topography due to ice movement could theoretically 19 feed back onto ice-flow dynamics. For example, the buildup of sedimentary 20 grounding-zone wedges at the marine termini of ice streams may stabilize 21 their position against local sea-level change. However, modeling of 22 subglacial till advection has previously relied on fluid-like rheologies, 23 which contrasts the now established concensus of Mohr-Coulomb plasticity. 24 25 In our work, we aim to improve the parameterization of till advection by 26 glacial flow. We compare a new continuum model for till against laboratory 27 consolidation and ring-shear experiments. We show how transient dynamics in 28 porosity and strength affect the mechanics under non-steady forcings, such 29 as glacier stick-slip or surge. We couple the till continuum model to an 30 ice-stream model, and demonstrate how till transport varies when ice flows 31 over simple soft-bed basal geometries, and affects ice-stream sensitivity 32 to external forcings. 33 34 Slides and video: 35 36 - slides: gopher://adamsgaard.dk/9/npub/agu2021-damsgaard.pdf 37 - video: https://adamsgaard.dk/video/agu2021-damsgaard.mp4 38 39 References: 40 41 [1] https://www.agu.org/Fall-Meeting 42