Geoscience Reference
In-Depth Information
Fig. 9.3 Snow on lake ice is
the main present problem in
thermodynamic ice models.
The photograph shows strange
spaghetti-like surface structure
formed during a snowstorm on
an open lake, Lake Suolij ä rvi in
Tuulos, Finland. Photograph
by Mr. Vesa Kaloinen, Tuulos,
printed with permission
timing of the snowfall is critical (Fig. 9.3 ). Also the ice break-up date depends on the
structure and thickness of the ice and snow and needs a physically realistic model, with
stratigraphy, to explore its variability. The main weakness in the present thermodynamic
lake ice models is indeed in the accounting for snow properties and processes. Another
question is the ice melting, which takes place at both boundaries and in the interior, the
partitioning depending on the ice structure and solar radiation.
The modelling problem for lake ice thickness can be approached with semi-analytic or
numerical methods. Semi-analytic methods are based on the degree-days and provide the
melting cycle from which simple
relations between winter climate and ice season characteristics can be derived. Numerical
models are designed to include the full ice physics in the analysis. In these models the
stratigraphy of ice, snow physics and atmospheric forcing can be treated in a realistic way,
first order approximation of the freezing
ice growth
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