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| Titel |
Debris-covered glacier energy balance model for Imja–Lhotse Shar Glacier in the Everest region of Nepal |
| VerfasserIn |
D. R. Rounce, D. J. Quincey, D. C. McKinney |
| 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. 6 ; Nr. 9, no. 6 (2015-12-07), S.2295-2310 |
| Datensatznummer |
250116881
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| Publikation (Nr.) |
 copernicus.org/tc-9-2295-2015.pdf |
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| Zusammenfassung |
| Debris thickness plays an important role in regulating ablation rates on
debris-covered glaciers as well as controlling the likely size and location
of supraglacial lakes. Despite its importance, lack of knowledge about
debris properties and associated energy fluxes prevents the robust inclusion
of the effects of a debris layer into most glacier surface energy balance
models. This study combines fieldwork with a debris-covered glacier energy
balance model to estimate debris temperatures and ablation rates on
Imja–Lhotse Shar Glacier located in the Everest region of Nepal. The debris
properties that significantly influence the energy balance model are the
thermal conductivity, albedo, and surface roughness. Fieldwork was conducted
to measure thermal conductivity and a method was developed using Structure
from Motion to estimate surface roughness. Debris temperatures measured
during the 2014 melt season were used to calibrate and validate a
debris-covered glacier energy balance model by optimizing the albedo,
thermal conductivity, and surface roughness at 10 debris-covered sites.
Furthermore, three methods for estimating the latent heat flux were
investigated. Model calibration and validation found the three methods had
similar performance; however, comparison of modeled and measured ablation
rates revealed that assuming the latent heat flux is zero may overestimate
ablation. Results also suggest that where debris moisture is unknown,
measurements of the relative humidity or precipitation may be used to
estimate wet debris periods, i.e., when the latent heat flux is non-zero.
The effect of temporal resolution on the model was also assessed and results
showed that both 6 h data and daily average data slightly underestimate
debris temperatures and ablation rates; thus these should only be used to
estimate rough ablation rates when no other data are available. |
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