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| Titel |
Soot on Snow experiment: bidirectional reflectance factor measurements of contaminated snow |
| VerfasserIn |
J. I. Peltoniemi, M. Gritsevich, T. Hakala, P. Dagsson-Waldhauserová, O. Arnalds, K. Anttila, H.-R. Hannula, N. Kivekäs, H. Lihavainen, O. Meinander, J. Svensson, A. Virkkula, G. de Leeuw |
| 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 (2015-12-11), S.2323-2337 |
| Datensatznummer |
250116883
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| Publikation (Nr.) |
 copernicus.org/tc-9-2323-2015.pdf |
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| Zusammenfassung |
In order to quantify the effects of absorbing contaminants on snow, a series
of spectral reflectance measurements were conducted. Chimney soot, volcanic
sand, and glaciogenic silt were deposited on a natural snow surface in a
controlled way as a part of the Soot on Snow (SoS) campaign. The
bidirectional reflectance factors of these soiled surfaces and untouched snow
were measured using the Finnish Geodetic Institute's Field
Goniospectropolariradiometer, FIGIFIGO.
A remarkable feature is the fact that the absorbing contaminants on snow
enhanced the metamorphism of snow under strong sunlight in our experiments.
Immediately after deposition, the contaminated snow surface appeared darker
than the natural snow in all viewing directions, but the absorbing particles
sank deep into the snow in minutes. The nadir measurement remained the
darkest, but at larger zenith angles, the surface of the contaminated snow
changed back to almost as white as clean snow. Thus, for a ground observer
the darkening caused by impurities can be completely invisible,
overestimating the albedo, but a nadir-observing satellite sees the darkest
points, underestimating the albedo. Through a reciprocity argument, we
predict that at noon, the albedo perturbation should be lower than in the
morning or afternoon. When sunlight stimulates sinking more than melting, the
albedo should be higher in the afternoon than in the morning, and vice versa
when melting dominates. However, differences in the hydrophobic properties,
porosity, clumping, or size of the impurities may cause different results
than observed in these measurements. |
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