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Simulating the evolution of the Antarctic ice sheet using the SIA

Simulating the evolution of the Antarctic ice sheet using the SIA. Pierre Dutrieux Sue Cook Ward van Pelt. The Shallow Ice Approximation (SIA). Thickness evolution:. Diffusivity:. “Shallow” ice sheet: L>>H Non-sliding ice flow diffuses the shape of the ice sheet. Numerical properties.

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Simulating the evolution of the Antarctic ice sheet using the SIA

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  1. Simulating the evolution of the Antarctic ice sheet using the SIA Pierre Dutrieux Sue Cook Ward van Pelt

  2. The Shallow Ice Approximation (SIA) Thickness evolution: Diffusivity: “Shallow” ice sheet: L>>H Non-sliding ice flow diffuses the shape of the ice sheet

  3. Numerical properties • Explicit scheme • Advantage: H determined by quantities known at the previous time-step • Time-step determined by stability criterion: • Staggered grid (Mahaffy, 1976)

  4. Scheme testingHalfar solution vs. model • Halfar solution: • Flat bed, zero mass balance, no calving • Radially symmetric shape

  5. Data • Present day input data for Antarctica: • Ice thickness • Bed topography • Precipitation http://websrv.cs.umt.edu/isis/index.phpPresent_Day_Antarctica (SeaRISE)

  6. Model resultsAntarctic experiment • 1000-yr simulation • Mass is conserved to within 500 m3

  7. Model resultsSmoothing the input data • Adjusted sampling of input data to remove some artifacts

  8. Model resultsSmoothing the input data Sub-sampled Smoothed Difference

  9. Model resultsImplement calving • Add calving • Criterion 1: • Criterion 2: No calving within initial grounding line

  10. Model resultsImplement calving

  11. Discussion • The SIA is a good description of shallow ice sheet evolution given improved mass balance data • Shortcomings: • No ice shelf formation • No sliding • No ice streams (To list a few!)

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