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| Titel |
Quantitative and qualitative constraints on hind-casting the formation of multiyear lake-ice covers at Lake El'gygytgyn |
| VerfasserIn |
M. Nolan |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 9, no. 3 ; Nr. 9, no. 3 (2013-06-19), S.1253-1269 |
| Datensatznummer |
250018065
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| Publikation (Nr.) |
 copernicus.org/cp-9-1253-2013.pdf |
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| Zusammenfassung |
| Analysis of the 3.6 Ma, 318 m long sediment core from Lake El'gygytgyn
suggests that the lake was covered by ice for millennia at a time for much
of its history and therefore this paper uses a suite of existing, simple, empirical
degree-day models of lake-ice growth and decay to place quantitative
constraints on air temperatures needed to maintain a permanent ice cover on
the lake. We also provide an overview of the modern climatological and
physical processes that relate to lake-ice growth and decay as a basis for
evaluating past climate and environmental conditions. Our modeling results
indicate that modern annual mean air temperature would only have to be
reduced by 3.3 °C ± 0.9 °C to initiate a
multiyear ice cover and a temperature reduction of at least 5.5 °C ± 1.0 °C
is likely needed to completely eliminate direct air–water
exchange of oxygen, conditions that have been inferred at Lake El'gygytgyn
from the analysis of sediment cores. Once formed, a temperature reduction of
only 1–3 °C relative to modern may be all that is required to
maintain multiyear ice. We also found that formation of multiyear ice
covers requires that positive degree days are reduced by about half the
modern mean, from about +608 to +322. A multiyear ice cover can persist
even with summer temperatures sufficient for a two-month long thawing
period, including a month above +4 °C. Thus, it is likely that
many summer biological processes and some lake-water warming and mixing may
still occur beneath multiyear ice-covers even if air–water exchange of
oxygen is severely restricted. |
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