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| Titel |
Large surface radiative forcing from topographic blowing snow residuals measured in the High Arctic at Eureka |
| VerfasserIn |
G. Lesins, L. Bourdages, T. J. Duck, J. R. Drummond, E. W. Eloranta, V. P. Walden |
| 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 ; 9, no. 6 ; Nr. 9, no. 6 (2009-03-16), S.1847-1862 |
| Datensatznummer |
250007079
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| Publikation (Nr.) |
 copernicus.org/acp-9-1847-2009.pdf |
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| Zusammenfassung |
| Ice crystals, also known as diamond dust, are suspended in the boundary
layer air under clear sky conditions during most of the Arctic winter in
Northern Canada. Occasionally ice crystal events can produce significantly
thick layers with optical depths in excess of 2.0 even in the absence of
liquid water clouds. Four case studies of high optical depth ice crystal
events at Eureka in the Nunavut Territory of Canada during the winter of
2006/07 are presented. They show that the measured ice crystal surface
infrared downward radiative forcing ranged from 8 to 36 W m−2 in the
wavelength band from 5.6 to 20 μm for 532 nm optical depths ranging
from 0.2 to 1.7. MODIS infrared and visible images and the operational
radiosonde wind profile were used to show that these high optical depth
events were caused by surface snow being blown off 600 to 800 m high
mountain ridges about 20 to 30 km North-West of Eureka and advected by the
winds towards Eureka as they settled towards the ground within the highly
stable boundary layer. This work presents the first study that demonstrates
the important role that surrounding topography plays in determining the
occurrence of high optical depth ice crystal events from residual blowing
snow that becomes a source of boundary layer ice crystals distinct from the
classical diamond dust phenomenon. |
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