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| Titel |
Freezing of lakes on the Swiss Plateau 1865-2100: combining long-term observations with modelling |
| VerfasserIn |
Matthias Huss, Harrie-Jan Hendricks Franssen, Felix Keller, Martin Funk, Martin Hoelzle |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250125935
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| Publikation (Nr.) |
 EGU/EGU2016-5593.pdf |
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| Zusammenfassung |
| The frequency of lake freeze-up on the Swiss plateau is a sensitive indicator of changes in
central European winter climate. Whereas smaller and more shallow lakes are reported to
completely freeze in more than 50% of the winters, large and deep lakes like Bodensee and
Zurichsee only froze one to very few times during the 20th century. The ice cover lasted
between some days and up to three months. The periodic freezing of lakes on the Swiss
plateau exerts considerable public attraction and is, in some cases, even an economic
factor.
In this study, we rely on an exceptional data set presented by Hendricks-Franssen and
Scherrer (2008) providing complete series of freeze-up events for a dozen lakes on the Swiss
plateau since 1901 based on direct observations. A new physically-based 1-D model for the
energy balance and the thermodynamics of lake ice is presented and validated against the
long-term observations. The model is driven with measured meteorological data as well as
with results of 10 regional climate models. We apply the model to compute continuous series
of freeze-up events between 1865 and 2100 for 14 Swiss lakes. In addition, the model
calculates the time evolution of the ice thickness and the corresponding bearing
capacity.
We discuss the potential of the model for simulating lake freeze-up events over the last
century in connection with the direct observations and simplified approaches for estimating
lake ice formation. Changes in freezing frequency are analysed over a period of more
than 200 years extending from the beginning of the instrumental record into the
future. Until 2050, freezing is still possible even for medium-sized lakes in extreme
winters. Towards the end of the 21st century, however, lakes on the Swiss plateau are
unlikely to freeze during winter with the exception of rare events on small lakes. For
an additional study site located at higher elevation in the Alps the model predicts
annual freezing until 2100 but with strongly reduced duration and ice thickness. |
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