Author(s): Matti Lepparanta
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Abstract: The ice and snow cover plays a crucial ro le in the physics and ecology o f freezing lakes. It forms a stationary, thin so lid sheet mod ifying the transfer of momentum, heat, light and matter between the atmosphere and the lake water body. When the temperature is at the melt ing point, liquid water inclusions may form in the ice and snow layers due to internal melt ing by so lar radiat ion and then have a major influence on the further melt ing or refreezing. The internal melt ing of the ice sheet lowers the strength of the ice and provides informat ion for predict ing the loss of bear ing capacity, the breakage of the ice cover, and consequent ice drift and loads on shoreline structures. Also the liquid water pockets inside the ice and snow are potential habitats for algae. In this paper a two-phase thermodynamic lake ice model is employed for simulat ions of the evo lution of ice thickness and internal structure of ice in the melt ing season. The model is based on the heat conduction and phase changes, which are allowed at boundaries and inside the snow and ice. The model pred icts the temperature and liquid water profiles of ice and snow layers as well as the thickness of ice and snow, and for the snow also the density profile. The model is used here for simulations o f the melt ing season for illustrat ive ideal cases and fo r real cases in Lake Vanajavesi, southern Finland with field data for comparisons. The simulations come out well and are sensit ive to the assumed albedo and light attenuation coefficient.
Year: 2010