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| Titel |
A comparison of glacier melt on debris-covered glaciers in the northern and southern Caucasus |
| VerfasserIn |
A. Lambrecht, C. Mayer, W. Hagg, V. Popovnin, A. Rezepkin, N. Lomidze, D. Svanadze |
| 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. 3 ; Nr. 5, no. 3 (2011-07-04), S.525-538 |
| Datensatznummer |
250002586
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| Publikation (Nr.) |
 copernicus.org/tc-5-525-2011.pdf |
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| Zusammenfassung |
| The glacier coverage in the Caucasus Mountains underwent considerable
changes during the last decades. In some regions, the observed reduction in
glacier area is comparable to those in the European Alps and the extent of
supra-glacial debris increased on many glaciers. Only a few glaciers in the
Caucasus are monitored on a regular basis, while for most areas no
continuous field measurements are available. In this study, regional
differences of the conditions for glacier melt with a special focus on
debris covered glacier tongues in the well-studied Adyl-su basin on the
northern slope of the Caucasus Mountains (Russia) is compared with the
Zopkhito basin which has similar characteristics but is located on the
southern slope in Georgia. The paper focuses on the effect of supra-glacial
debris cover on glacier summer melt. There are systematic differences in the
distribution and increase of the debris cover on the glaciers of the two
basins. In the Adyl-su basin an extensive debris cover on the glacier
tongues is common, however, only those glacier tongues that are positioned
at the lowest elevations in the Zopkhito basin show a considerable extent of
supra-glacial debris. The observed increase in debris cover is considerably
stronger in the north. Field experiments show that thermal resistance of the
debris cover in both basins is somewhat higher than in other glaciated
regions of the world, but there is also a significant difference between the
two regions. A simple ablation model accounting for the effect of debris
cover on ice melt shows that melt rates are considerably higher in the
northern basin despite a wider debris distribution. This difference between
the two regions can be attributed to different meteorological conditions
which are characterised by more frequent cloud cover and precipitation in
the south. Furthermore ablation is strongly influenced by the occurrence of
supra-glacial debris cover in both basins, reducing the total amount of melt
on the studied glaciers by about 25 %. This effect mitigates glacier
retreat in the lower sectors of the ablation zones considerably. The
sensitivity to moderate changes in the debris cover, however, is rather
small which implies only gradual changes of the melt regime due to debris
cover dynamics during the near future. |
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