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| Titel |
Impact of debris cover on glacier ablation and atmosphere–glacier feedbacks in the Karakoram |
| VerfasserIn |
E. Collier, F. Maussion, L. I. Nicholson, T. Mölg, W. W. Immerzeel, A. B. G. Bush |
| 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. 4 ; Nr. 9, no. 4 (2015-08-20), S.1617-1632 |
| Datensatznummer |
250116837
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| Publikation (Nr.) |
 copernicus.org/tc-9-1617-2015.pdf |
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| Zusammenfassung |
| The Karakoram range of the Hindu-Kush Himalaya is characterized by both extensive glaciation
and a widespread prevalence of surficial debris cover on the glaciers. Surface debris exerts
a strong control on glacier surface-energy and mass fluxes and, by modifying surface boundary
conditions, has the potential to alter atmosphere–glacier feedbacks. To date, the influence of
debris on Karakoram glaciers has only been directly assessed by a small number of glaciological
measurements over short periods. Here, we include supraglacial debris in a high-resolution,
interactively coupled atmosphere–glacier modeling system. To investigate glaciological and
meteorological changes that arise due to the presence of debris, we perform two simulations
using the coupled model from 1 May to 1 October 2004: one that treats all glacier surfaces
as debris-free and one that introduces a simplified specification for the debris thickness.
The basin-averaged impact of debris is a reduction in ablation of ~ 14 %, although the
difference exceeds 5 m w.e. on the lowest-altitude glacier tongues. The relatively modest
reduction in basin-mean mass loss results in part from non-negligible sub-debris melt rates under
thicker covers and from compensating increases in melt under thinner debris, and may help to
explain the lack of distinct differences in recent elevation changes between clean and
debris-covered ice. The presence of debris also strongly alters the surface boundary condition
and thus heat exchanges with the atmosphere; near-surface meteorological fields at lower
elevations and their vertical gradients; and the atmospheric boundary layer development.
These findings are relevant for glacio-hydrological studies on debris-covered glaciers and
contribute towards an improved understanding of glacier behavior in the Karakoram. |
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