Debris thickness of glaciers in the Everest area (Nepal Himalaya) derived from satellite imagery using a nonlinear energy balance model
Debris thickness is an important characteristic of debris-covered glaciers in the Everest region of the Himalayas. The debris thickness controls the melt rates of the glaciers, which has large implications for hydrologic models, the glaciers' response to climate change, and the development of g...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2014-07-01
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| Series: | The Cryosphere |
| Online Access: | http://www.the-cryosphere.net/8/1317/2014/tc-8-1317-2014.pdf |
| Summary: | Debris thickness is an important characteristic of debris-covered glaciers
in the Everest region of the Himalayas. The debris thickness controls the
melt rates of the glaciers, which has large implications for hydrologic
models, the glaciers' response to climate change, and the development of
glacial lakes. Despite its importance, there is little knowledge of how the
debris thickness varies over these glaciers. This paper uses an energy
balance model in conjunction with Landsat7 Enhanced Thematic Mapper Plus (ETM+) satellite imagery to
derive thermal resistances, which are the debris thickness divided by the
thermal conductivity. Model results are reported in terms of debris
thickness using an effective thermal conductivity derived from field data.
The developed model accounts for the nonlinear temperature gradient in the
debris cover to derive reasonable debris thicknesses. Fieldwork performed on
Imja–Lhotse Shar Glacier in September 2013 was used to compare to the
modeled debris thicknesses. Results indicate that accounting for the
nonlinear temperature gradient is crucial. Furthermore, correcting the
incoming shortwave radiation term for the effects of topography and
resampling to the resolution of the thermal band's pixel is imperative to
deriving reasonable debris thicknesses. Since the topographic correction is
important, the model will improve with the quality of the digital elevation model (DEM). The main
limitation of this work is the poor resolution (60 m) of the satellite's
thermal band. The derived debris thicknesses are reasonable at this
resolution, but trends related to slope and aspect are unable to be modeled
on a finer scale. Nonetheless, the study finds this model derives reasonable
debris thicknesses on this scale and was applied to other debris-covered
glaciers in the Everest region. |
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| ISSN: | 1994-0416 1994-0424 |