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| Titel |
Probabilistic parameterisation of the surface mass balance–elevation feedback in regional climate model simulations of the Greenland ice sheet |
| VerfasserIn |
T. L. Edwards, X. Fettweis, O. Gagliardini, F. Gillet-Chaulet, H. Goelzer, J. M. Gregory, M. Hoffman, P. Huybrechts, A. J. Payne, M. Perego, S. Price, A. Quiquet, C. Ritz |
| 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 ; 8, no. 1 ; Nr. 8, no. 1 (2014-01-30), S.181-194 |
| Datensatznummer |
250116015
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| Publikation (Nr.) |
 copernicus.org/tc-8-181-2014.pdf |
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| Zusammenfassung |
We present a new parameterisation that relates surface mass balance (SMB: the
sum of surface accumulation and surface ablation) to changes in surface
elevation of the Greenland ice sheet (GrIS) for the MAR (Modèle Atmosphérique
Régional: Fettweis, 2007) regional climate
model. The motivation is to dynamically adjust SMB as the GrIS evolves,
allowing us to force ice sheet models with SMB simulated by MAR while
incorporating the SMB–elevation feedback, without the substantial technical
challenges of coupling ice sheet and climate models. This also allows us to
assess the effect of elevation feedback uncertainty on the GrIS contribution
to sea level, using multiple global climate and ice sheet models, without the
need for additional, expensive MAR simulations.
We estimate this relationship separately below and above the equilibrium line
altitude (ELA, separating negative and positive SMB) and for regions north
and south of 77° N, from a set of MAR simulations in which we alter
the ice sheet surface elevation. These give four "SMB lapse rates",
gradients that relate SMB changes to elevation changes. We assess
uncertainties within a Bayesian framework, estimating probability
distributions for each gradient from which we present best estimates and
credibility intervals (CI) that bound 95% of the probability. Below the
ELA our gradient estimates are mostly positive, because SMB usually increases
with elevation: 0.56 (95% CI: −0.22 to 1.33) kg m−3 a−1 for
the north, and 1.91 (1.03 to 2.61) kg m−3 a−1 for the south.
Above the ELA, the gradients are much smaller in magnitude: 0.09 (−0.03 to
0.23) kg m−3 a−1 in the north, and 0.07 (−0.07 to
0.59) kg m−3 a−1 in the south, because SMB can either increase
or decrease in response to increased elevation.
Our statistically founded approach allows us to make probabilistic
assessments for the effect of elevation feedback uncertainty on sea level
projections (Edwards et al., 2014). |
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