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| Titel |
A new sub-grid surface mass balance and flux model for continental-scale ice sheet modelling: testing and last glacial cycle |
| VerfasserIn |
K. Le Morzadec, L. Tarasov, M. Morlighem, H. Seroussi |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1991-959X
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| Digitales Dokument |
URL |
| Erschienen |
In: Geoscientific Model Development ; 8, no. 10 ; Nr. 8, no. 10 (2015-10-08), S.3199-3213 |
| Datensatznummer |
250116602
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| Publikation (Nr.) |
 copernicus.org/gmd-8-3199-2015.pdf |
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| Zusammenfassung |
To investigate ice sheet evolution over the timescale of a glacial
cycle, 3-D ice sheet models (ISMs) are typically run at "coarse" grid
resolutions (10–50 km) that do not resolve individual
mountains. This will introduce to-date unquantified errors in sub-grid
(SG) transport, accumulation and ablation for regions of rough
topography. In the past, synthetic hypsometric curves, a statistical
summary of the topography, have been used in ISMs to describe the
variability of these processes. However, there has yet to be detailed
uncertainty analysis of this approach.
We develop a new flow line SG model for embedding in coarse resolution
models.
A 1 km resolution digital elevation model was used to compute the local
hypsometric curve for each coarse grid (CG) cell and to determine local parameters to represent the
hypsometric bins' slopes and widths. The 1-D mass transport for the SG
model is computed with the shallow ice approximation. We test this
model against simulations from the 3-D Ice Sheet System Model
(ISSM) run at 1 km grid resolution. Results show that none of
the alternative parameterizations explored were able to adequately
capture SG surface mass balance and flux processes. Via
glacial cycle ensemble results for North America, we quantify the
impact of SG model coupling in an ISM. We show that SG process
representation and associated parametric uncertainties, related to the
exchange of ice between the SG and CG cells, can have
significant (up to 35 m eustatic sea level equivalent for the North American ice
complex) impact on modelled ice sheet evolution. |
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