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| Titel |
Committed retreat of Smith, Pope, and Kohler Glaciers over the next 30 years inferred by transient model calibration |
| VerfasserIn |
D. N. Goldberg, P. Heimbach, I. Joughin, B. Smith |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1994-0416
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| Digitales Dokument |
URL |
| Erschienen |
In: The Cryosphere ; 9, no. 6 ; Nr. 9, no. 6 (2015-12-21), S.2429-2446 |
| Datensatznummer |
250116890
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| Publikation (Nr.) |
 copernicus.org/tc-9-2429-2015.pdf |
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| Zusammenfassung |
| A glacial flow model of Smith, Pope and Kohler Glaciers is
calibrated by means of control methods against time varying, annually resolved
observations of ice height and velocities, covering the period 2002 to 2011.
The inversion – termed "transient calibration" – produces an optimal set
of time-mean, spatially varying parameters together with a time-evolving
state that accounts for the transient nature of observations and the model
dynamics. Serving as an optimal initial condition, the estimated state for
2011 is used, with no additional forcing, for predicting grounded ice volume
loss and grounding line retreat over the ensuing 30 years. The transiently
calibrated model predicts a near-steady loss of grounded ice volume of
approximately 21 km3 a−1 over this period, as well as loss of
33 km2 a−1 grounded area. We contrast this prediction with one
obtained following a commonly used "snapshot" or steady-state inversion,
which does not consider time dependence and assumes all observations to be
contemporaneous. Transient calibration is shown to achieve a better fit with
observations of thinning and grounding line retreat histories, and yields a
quantitatively different projection with respect to ice volume loss and
ungrounding. Sensitivity studies suggest large near-future levels of
unforced, i.e., committed sea level contribution from these ice streams under
reasonable assumptions regarding uncertainties of the unknown parameters. |
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