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| Titel |
Diurnal variations in the UV albedo of arctic snow |
| VerfasserIn |
O. Meinander, A. Kontu, K. Lakkala, A. Heikkilä, L. Ylianttila, M. Toikka |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 8, no. 21 ; Nr. 8, no. 21 (2008-11-14), S.6551-6563 |
| Datensatznummer |
250006447
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| Publikation (Nr.) |
 copernicus.org/acp-8-6551-2008.pdf |
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| Zusammenfassung |
| The relevance of snow for climate studies is based on its physical
properties, such as high surface reflectivity. Surface ultraviolet (UV)
albedo is an essential parameter for various applications based on radiative
transfer modeling. Here, new continuous measurements of the local UV albedo
of natural Arctic snow were made at Sodankylä (67°22'N, 26°39'E,
179 m a.s.l.) during the spring of 2007. The data were logged at 1-min
intervals. The accumulation of snow was up to 68 cm. The surface layer
thickness varied from 0.5 to 35 cm with the snow grain size between 0.2 and
2.5 mm. The midday erythemally weighted UV albedo ranged from 0.6 to 0.8 in
the accumulation period, and from 0.5 to 0.7 during melting. During the snow
melt period, under cases of an almost clear sky and variable cloudiness, an
unexpected diurnal decrease of 0.05 in albedo soon after midday, and
recovery thereafter, was detected. This diurnal decrease in albedo was found
to be asymmetric with respect to solar midday, thus indicating a change in
the properties of the snow. Independent UV albedo results with two different
types of instruments confirm these findings. The measured temperature of the
snow surface was below 0°C on the following mornings. Hence, the
reversible diurnal change, evident for ~1–2 h, could be explained
by the daily metamorphosis of the surface of the snowpack, in which the
temperature of the surface increases, melting some of the snow to liquid
water, after which the surface freezes again. |
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