Large ensemble modeling of the last deglacial retreat of the West Antarctic Ice Sheet: comparison of simple and advanced statistical techniques
A 3-D hybrid ice-sheet model is applied to the last deglacial retreat of the West Antarctic Ice Sheet over the last ∼ 20 000 yr. A large ensemble of 625 model runs is used to calibrate the model to modern and geologic data, including reconstructed grounding lines, relative sea-level records, eleva...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-05-01
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| Series: | Geoscientific Model Development |
| Online Access: | http://www.geosci-model-dev.net/9/1697/2016/gmd-9-1697-2016.pdf |
| Summary: | A 3-D hybrid ice-sheet model is applied to the last deglacial retreat of the
West Antarctic Ice Sheet over the last ∼ 20 000 yr. A large ensemble
of 625 model runs is used to calibrate the model to modern and geologic data,
including reconstructed grounding lines, relative sea-level records,
elevation–age data and uplift rates, with an aggregate score computed for
each run that measures overall model–data misfit. Two types of statistical
methods are used to analyze the large-ensemble results: simple averaging
weighted by the aggregate score, and more advanced Bayesian techniques
involving Gaussian process-based emulation and calibration, and Markov chain
Monte Carlo. The analyses provide sea-level-rise envelopes with well-defined
parametric uncertainty bounds, but the simple averaging method only provides
robust results with full-factorial parameter sampling in the large ensemble.
Results for best-fit parameter ranges and envelopes of equivalent sea-level
rise with the simple averaging method agree well with the more advanced
techniques. Best-fit parameter ranges confirm earlier values expected from
prior model tuning, including large basal sliding coefficients on modern
ocean beds. |
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| ISSN: | 1991-959X 1991-9603 |