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| Titel |
The effects of additional black carbon on the albedo of Arctic sea ice: variation with sea ice type and snow cover |
| VerfasserIn |
A. A. Marks, M. D. King |
| 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 ; 7, no. 4 ; Nr. 7, no. 4 (2013-07-30), S.1193-1204 |
| Datensatznummer |
250017995
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| Publikation (Nr.) |
 copernicus.org/tc-7-1193-2013.pdf |
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| Zusammenfassung |
| The response of the albedo of bare sea ice and snow-covered sea ice to the addition of black carbon is calculated.
Visible light absorption and light-scattering cross-sections are derived for a typical first-year and multi-year sea ice
with both "dry" and "wet" snow types. The cross-sections are derived using data from a 1970s field study that
recorded both reflectivity and light penetration in Arctic sea ice and snow overlying sea ice. The variation of
absorption cross-section over the visible wavelengths suggests black carbon is the dominating light-absorbing
impurity. The response of first-year and multi-year sea ice albedo to increasing black carbon, from 1 to 1024 ng g−1,
in a top 5 cm layer of a 155 cm-thick sea ice was calculated using a radiative-transfer model. The albedo of the
first-year sea ice is more sensitive to additional loadings of black carbon than the multi-year sea ice. An addition
of 8 ng g−1 of black carbon causes a decrease to 98.7% of the original albedo for first-year sea
ice compared to a decrease to 99.7% for the albedo of multi-year sea ice, at a wavelength of 500 nm. The
albedo of sea ice is surprisingly unresponsive to additional black carbon up to 100 ng g−1 . Snow layers
on sea ice may mitigate the effects of black carbon in sea ice. Wet and dry snow layers of 0.5, 1, 2, 5 and 10 cm
depth were added onto the sea ice surface. The albedo of the snow surface was calculated whilst the black carbon
in the underlying sea ice was increased. A layer of snow 0.5 cm thick greatly diminishes the effect of black carbon
in sea ice on the surface albedo. The albedo of a 2–5 cm snow layer (less than the e-folding depth of snow)
is still influenced by the underlying sea ice, but the effect of additional black carbon in the sea ice is masked. |
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