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| Titel |
Response of ice cover on shallow lakes of the North Slope of Alaska to contemporary climate conditions (1950-2011): radar remote-sensing and numerical modeling data analysis |
| VerfasserIn |
C. M. Surdu, C. R. Duguay, L. C. Brown, D. Fernández Prieto |
| 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 ; 8, no. 1 ; Nr. 8, no. 1 (2014-01-30), S.167-180 |
| Datensatznummer |
250116014
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| Publikation (Nr.) |
 copernicus.org/tc-8-167-2014.pdf |
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| Zusammenfassung |
| Air temperature and winter precipitation changes over the last five decades
have impacted the timing, duration, and thickness of the ice cover on Arctic
lakes as shown by recent studies. In the case of shallow tundra lakes, many
of which are less than 3 m deep, warmer climate conditions could result in
thinner ice covers and consequently, in a smaller fraction of lakes freezing
to their bed in winter. However, these changes have not yet been
comprehensively documented. The analysis of a 20 yr time series of European
remote sensing satellite ERS-1/2 synthetic aperture radar (SAR) data and a
numerical lake ice model were employed to determine the response of ice cover
(thickness, freezing to the bed, and phenology) on shallow lakes of the North
Slope of Alaska (NSA) to climate conditions over the last six decades. Given
the large area covered by these lakes, changes in the regional climate and
weather are related to regime shifts in the ice cover of the lakes. Analysis
of available SAR data from 1991 to 2011, from a sub-region of the NSA near
Barrow, shows a reduction in the fraction of lakes that freeze to the bed in
late winter. This finding is in good agreement with the decrease in ice
thickness simulated with the Canadian Lake Ice Model (CLIMo), a lower
fraction of lakes frozen to the bed corresponding to a thinner ice cover.
Observed changes of the ice cover show a trend toward increasing floating ice
fractions from 1991 to 2011, with the greatest change occurring in April,
when the grounded ice fraction declined by 22% (α = 0.01). Model
results indicate a trend toward thinner ice covers by 18–22 cm (no-snow and
53% snow depth scenarios, α = 0.01) during the 1991–2011 period
and by 21–38 cm (α = 0.001) from 1950 to 2011. The longer trend
analysis (1950–2011) also shows a decrease in the ice cover duration by
~24 days consequent to later freeze-up dates by 5.9 days (α
= 0.1) and earlier break-up dates by 17.7–18.6 days (α
= 0.001). |
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