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| Titel |
A preliminary assessment of glacier melt-model parameter sensitivity and transferability in a dry subarctic environment |
| VerfasserIn |
A. H. MacDougall, B. A. Wheler, G. E. Flowers |
| 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 ; 5, no. 4 ; Nr. 5, no. 4 (2011-11-16), S.1011-1028 |
| Datensatznummer |
250002756
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| Publikation (Nr.) |
 copernicus.org/tc-5-1011-2011.pdf |
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| Zusammenfassung |
| Efforts to project the long-term melt of mountain glaciers and ice-caps
require that melt models developed and calibrated for well studied locations
be transferable over large regions. Here we assess the sensitivity and
transferability of parameters within several commonly used melt models for
two proximal sites in a dry subarctic environment of northwestern Canada. The
models range in complexity from a classical degree-day model to a simplified
energy-balance model. Parameter sensitivity is first evaluated by tuning the
melt models to the output of an energy balance model forced with idealized
inputs. This exercise allows us to explore parameter sensitivity both to
glacier geometric attributes and surface characteristics, as well as to
meteorological conditions. We then investigate the effect of model tuning
with different statistics, including a weighted coefficient of determination
(wR2), the Nash-Sutcliffe efficiency criterion (E), mean absolute error
(MAE) and root mean squared error (RMSE). Finally we examine model parameter
transferability between two neighbouring glaciers over two melt seasons using
mass balance data collected in the St. Elias Mountains of the southwest
Yukon. The temperature-index model parameters appear generally sensitive to
glacier aspect, mean surface elevation, albedo, wind speed, mean annual
temperature and temperature lapse rate. The simplified energy balance model
parameters are sensitive primarily to snow albedo. Model tuning with E, MAE
and RMSE produces similar, or in some cases identical, parameter values. In
twelve tests of spatial and/or temporal parameter transferability, the
results with the lowest RMSE values with respect to ablation stake
measurements were achieved twice with a classical temperature-index
(degree-day) model, three times with a temperature-index model in which the
melt parameter is a function of potential radiation, and seven times with a
simplified energy-balance model. A full energy-balance model produced better
results than the other models in nine of twelve cases, though the tuning of
this model differs from that of the others. |
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