adamsgaard.dk

008-commsenv.html (4192B)

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 <p>The majority of glaciers and ice sheets flow on a bed of loose
 and thawed sediments.  These sediments are weakened by pressurized
 glacial meltwater, and their lubrication accelerates the ice movement.
 In formerly-glaciated areas of the world, for example Northern
 Europe, North America, and in the forelands of the Alps, the landscape
 was reshaped and remolded by past ice moving the sediments along
 with its flow.  Sediment movement is also observed under current
 glaciers, both the fast-moving ice streams of the Greenland and
 Antarctic ice sheets, but also smaller glaciers in the mountainous
 areas of Alaska, northern Scandinavia, and elsewhere.  The movement
 of sediment could be important for the progression of glaciations,
 and influence how resilient marine-terminating ice streams are
 against sea-level rise.</p>
 
 <p>Today, the Nature-group journal <a
 href="https://www.nature.com/commsenv/">Communications Earth &amp;
 Environment</a> published my paper on sediment beneath ice.  Together
 with co-authors <a
 href="https://sites.google.com/site/gorenliran/home">Liran Goren</a>,
 University of the Negev (Israel), and <a
 href="https://profiles.stanford.edu/jenny-suckale">Jenny Suckale</a>,
 Stanford University (California, USA), we present a new computer
 model that simulates the coupled mechanical behavior of ice, sediment,
 and meltwater.  We calibrate the model against real materials, and
 provide a way for including sediment transport in ice-flow models.
 We also show that water-pressure variations with the right frequency
 can create create very weak sections inside the bed, and this greatly
 enhances sediment transport.  I designed the freely-available program
 <a href="https://src.adamsgaard.dk/cngf-pf">cngf-pf</a> for the
 simulations.</p>
 
 <h2>Abstract</h2>
 <blockquote>
 <b>Water pressure fluctuations control variability in sediment flux
 and slip dynamics beneath glaciers and ice streams</b>
 <br><br>
 Rapid ice loss is facilitated by sliding over beds consisting of
 reworked sediments and erosional products, commonly referred to as
 till. The dynamic interplay between ice and till reshapes the bed,
 creating landforms preserved from past glaciations. Leveraging the
 imprint left by past glaciations as constraints for projecting
 future deglaciation is hindered by our incomplete understanding of
 evolving basal slip. Here, we develop a continuum model of
 water-saturated, cohesive till to quantify the interplay between
 meltwater percolation and till mobilization that governs changes
 in the depth of basal slip under fast-moving ice. Our model explains
 the puzzling variability of observed slip depths by relating localized
 till deformation to perturbations in pore-water pressure. It
 demonstrates that variable slip depth is an inherent property of
 the ice-meltwater-till system, which could help understand why some
 paleo-landforms like grounding-zone wedges appear to have formed
 quickly relative to current till-transport rates.
 </blockquote>
 
 <h2>Metrics</h2>
 <p>It is a substantial task to prepare a scientific publication.  The
 commit counts below mark the number of revisions done during
 preparation of this paper:</p>
 
 <ul>
         <li>Main article text: 239 commits</li>
         <li>Supplementary information text: 35 commits</li>
         <li>Experiments and figures: 282 commits</li>
         <li>Simulation software: 354 commits</li>
 </ul>
 
 <h2>Links and references:</h2>
 <ul>
 	<li><a href="https://doi.org/10.1038/s43247-020-00074-7">Publication on journal webpage</a> (open access)</li>
 	<li><a href="papers/Damsgaard%20et%20al%202020%20Water%20pressure%20fluctuations%20control%20variability%20in%20sediment%20flux%20and%20slip%20dynamics%20beneath%20glaciers%20and%20ice%20streams.pdf">Article PDF</a> (1.6 MB)</li>
 	<li><a href="papers/Damsgaard%20et%20al%202020%20Water%20pressure%20fluctuations%20control%20variability%20in%20sediment%20flux%20and%20slip%20dynamics%20beneath%20glaciers%20and%20ice%20streams%20SI.pdf">Supplementary information PDF</a> (0.4 MB)</li>
 	<li><a href="https://src.adamsgaard.dk/cngf-pf-exp1">Source code for producing figures</a></li>
 	<li><a href="https://src.adamsgaard.dk/cngf-pf">Simulation software</a></li>
 </ul>