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t007-commsenv.html (3644B)
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1 <p>The majority of glaciers and ice sheets flow on a bed of loose
2 and thawed sediments. These sediments are weakened by pressurized
3 glacial meltwater, and their lubrication accelerates the ice movement.
4 In formerly-glaciated areas of the world, for example Northern
5 Europe, North America, and in the forelands of the Alps, the landscape
6 is reshaped and remolded by past ice moving the sediments along
7 with its flow. The sediment movement is also observed under current
8 glaciers, both the fast-moving ice streams of the Greenland and
9 Antarctic ice sheets, as well as smaller glaciers in the mountainous
10 areas of Alaska, northern Sweden, and elsewhere. The movement of
11 sediment could be important for the past progression of glaciations,
12 and how resilient marine-terminating ice streams are against sea-level
13 rise.</p>
14
15 <p>Today, the Nature-group journal <a
16 href="https://www.nature.com/commsenv/">Communications Earth &
17 Environment</a> published my paper on sediment beneath ice. Together
18 with co-authors Liran Goren, University of the Negev (Israel), and
19 Jenny Suckale, Stanford University (California, USA), we present a
20 new computer model that simulates the coupled mechanical behavior
21 of ice, sediment, and meltwater. We calibrate the model against
22 real materials, and provide a way forward for including sediment
23 transport in ice-flow models. We also show that water-pressure
24 variations with the right frequency can create create very weak
25 sections inside the bed, and this greatly enhances sediment transport.
26 I designed the freely-available program <a
27 href="https://src.adamsgaard.dk/cngf-pf">cngf-pf</a> for the
28 simulations.</p>
29
30 <h2>Abstract</h2>
31 <blockquote>
32 <b>Water pressure fluctuations control variability in sediment flux
33 and slip dynamics beneath glaciers and ice streams</b>
34 <br><br>
35 Rapid ice loss is facilitated by sliding over beds consisting of
36 reworked sediments and erosional products, commonly referred to as
37 till. The dynamic interplay between ice and till reshapes the bed,
38 creating landforms preserved from past glaciations. Leveraging the
39 imprint left by past glaciations as constraints for projecting
40 future deglaciation is hindered by our incomplete understanding of
41 evolving basal slip. Here, we develop a continuum model of
42 water-saturated, cohesive till to quantify the interplay between
43 meltwater percolation and till mobilization that governs changes
44 in the depth of basal slip under fast-moving ice. Our model explains
45 the puzzling variability of observed slip depths by relating localized
46 till deformation to perturbations in pore-water pressure. It
47 demonstrates that variable slip depth is an inherent property of
48 the ice-meltwater-till system, which could help understand why some
49 paleo-landforms like grounding-zone wedges appear to have formed
50 quickly relative to current till-transport rates.
51 </blockquote>
52
53 <h2>Metrics</h2>
54 <p>It is a substantial task to prepare a scientific publication. The
55 commit counts below mark the number of revisions done during
56 preparation of this paper:</p>
57
58 <ul>
59 <li>Main article text: 239 commits</li>
60 <li>Supplementary information text: 35 commits</li>
61 <li>Experiments and figures: 282 commits</li>
62 <li>Simulation software: 354 commits</li>
63 </ul>
64
65 <h2>Links and references:</h2>
66 <ul>
67 <li><a href="">Publication on journal webpage</a></li>
68 <li><a href="">Article PDF</a> (?? MB)</li>
69 <li><a href="">Supplementary information PDF</a> (?? MB)</li>
70 <li><a href="https://src.adamsgaard.dk/cngf-pf-exp1">Source code for producing figures</a></li>
71 <li><a href="https://src.adamsgaard.dk/cngf-pf">Simulation software</a></li>
72 </ul>