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The Cryosphere An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/tc-2018-64
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
13 Apr 2018
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal The Cryosphere (TC).
Impacts of topographic shading on direct solar radiation for valley glaciers in complex topography
Matthew H. Olson and Summer B. Rupper Department of Geography, University of Utah, Salt Lake City, 84112, USA
Abstract. Topographic shading, including both shaded relief and cast shadowing, plays a fundamental role in determining direct solar radiation on glacier ice. However, this parameter has been oversimplified or incorrectly incorporated in surface energy balance models in some past studies. Here we develop a topographic solar radiation model to examine the variability in irradiance throughout the glacier melt season due to topographic shading and combined slope and aspect. We apply the model to multiple glaciers in High Mountain Asia (HMA), and test the sensitivity of shading to valley-aspect and latitude. Our results show that topographic shading significantly alters the potential direct clear-sky solar radiation received at the surface for valley glaciers in HMA, particularly for north- and south-facing glaciers. Additionally, we find that shading can be extremely impactful in the ablation zone. Cast shadowing is the dominant mechanism in determining total shading for valley glaciers in parts of HMA, especially at lower elevations. Although shading has some predictable characteristics, it is overall extremely variable between glacial valleys. Our results suggest that topographic shading is not only an important factor contributing to surface energy balance, but could also influence glacier response and mass balance estimates throughout HMA.
Citation: Olson, M. H. and Rupper, S. B.: Impacts of topographic shading on direct solar radiation for valley glaciers in complex topography, The Cryosphere Discuss., https://doi.org/10.5194/tc-2018-64, in review, 2018.
Matthew H. Olson and Summer B. Rupper
Matthew H. Olson and Summer B. Rupper
Matthew H. Olson and Summer B. Rupper

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Short summary
Topographic shading can significantly alter the solar radiation arriving on the surface of glaciers in complex terrain. We determine the change in irradiance due to shading for multiple glaciers in the Himalaya, and compare these results to the affect of slope and aspect. We found that shadows cast from surrounding terrain are important, particularly at lower elevations, and must be incorporated when modeling. We also found that north- and south-facing glaciers are more sensitive to shading.
Topographic shading can significantly alter the solar radiation arriving on the surface of...
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