Daniel Shapero Research Scientist/Engineer - Senior shapero@apl.washington.edu Phone 206-543-1348 |
Education
B.S. Applied Mathematics, McGill University (Montreal, QC, Canada), 2010
Ph.D. Applied Mathematics, University of Washington - Seattle, 2017
Publications |
2000-present and while at APL-UW |
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Ocean-induced melt volume directly paces ice loss from Pine Island Glacier Joughin, I., D. Shapero, P. Dutrieux, and B. Smith, "Ocean-induced melt volume directly paces ice loss from Pine Island Glacier," Sci. Adv., 7, doi:10.1126/sciadv.abi5738, 2021. |
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22 Oct 2021 ![]() |
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The spatial distribution of ocean-induced melting beneath buttressing ice shelves is often cited as an important factor controlling Antarctica’s sea-level contribution. Using numerical simulations, we investigate the relative sensitivity of grounded-ice loss to the spatial distribution and overall volume of ice-shelf melt over two centuries. Contrary to earlier work, we find only minor sensitivity to melt distribution (<6%), with a linear dependence of ice loss on the total melt. Thus, less complex models that need not reproduce the detailed melt distribution may simplify the projection of future sea level. The linear sensitivity suggests a contribution of up to 5.1 cm from Pine Island Glacier over the next two centuries given anticipated levels of ocean warming, provided its ice shelf does not collapse because of other causes. |
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icepack: A new glacier flow modeling package in Python, version 1.0 Shapero, D.R., J.A. Badgeley, A.O. Hoffman, and I.R. Joughin, "icepack: A new glacier flow modeling package in Python, version 1.0," Geosci. Model Dev., 14, 4593-4616, doi:10.5194/gmd-14-4593-2021, 2021. |
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26 Jul 2021 ![]() |
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We introduce a new software package called 'icepack' for modeling the flow of glaciers and ice sheets. The icepack package is built on the finite element modeling library Firedrake, which uses the Unified Form Language (UFL), a domain-specific language embedded into Python for describing weak forms of partial differential equations. The diagnostic models in icepack are formulated through action principles that are specified in UFL. The components of each action functional can be substituted for different forms of the user's choosing, which makes it easy to experiment with the model physics. The action functional itself can be used to define a solver convergence criterion that is independent of the mesh and requires little tuning on the part of the user. The icepack package includes the 2D shallow ice and shallow stream models. We have also defined a 3D hybrid model based on spectral semi-discretization of the BlatterPattyn equations. Finally, icepack includes a GaussNewton solver for inverse problems that runs substantially faster than the BroydenFletcherGoldfarbShanno (BFGS) method often used in the glaciological literature. The overall design philosophy of icepack is to be as usable as possible for a wide a swath of the glaciological community, including both experts and novices in computational science. |
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Ice-shelf retreat drives recent Pine Island Glacier speedup Joughin, I., D. Shapero, B. Smith, P. Dutrieux, and M. Barham, "Ice-shelf retreat drives recent Pine Island Glacier speedup," Sci. Adv., 7, doi:10.1126/sciadv.abg3080, 2021. |
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11 Jun 2021 ![]() |
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Speedup of Pine Island Glacier over the past several decades has made it Antarctica's largest contributor to sea-level rise. The past speedup is largely due to grounding-line retreat in response to ocean-induced thinning that reduced ice-shelf buttressing. While speeds remained fairly steady from 2009 to late 2017, our Copernicus Sentinel 1A/B-derived velocity data show a >12% speedup over the past 3 years, coincident with a 19-km retreat of the ice shelf. We use an ice-flow model to simulate this loss, finding that accelerated calving can explain the recent speedup, independent of the grounding-line, melt-driven processes responsible for past speedups. If the ice shelf’s rapid retreat continues, it could further destabilize the glacier far sooner than would be expected due to surface- or ocean-melting processes. |
In The News
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Edge of Pine Island Glacier’s ice shelf is ripping apart, causing key Antarctic glacier to gain speed UW News, Hannah Hickey For decades, the ice shelf helping to hold back one of the fastest-moving glaciers in Antarctica has gradually thinned. Analysis of satellite images reveals a more dramatic process in recent years: From 2017 to 2020, large icebergs at the ice shelf’s edge broke off, and the glacier sped up. |
11 Jun 2021
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