Author(s): Matti Lepparanta; Georgiy Kirillin; Elisa Lindgren
Linked Author(s): Matti Leppäranta, Georgiy Kirillin
Keywords: No keywords
Abstract: Melting of lake ice is driven primarily by solar radiation. Complications arise from large variability of optical properties of ice in the melting season. To gain more understanding of the melting process, field experiments have been performed in Finnish lakes from the boreal zone to Arctic tundra. In particular, an extensive research program was carried through in Lake Kilpisjarvi in the tundra zone in 2013–2014. The surface area of the lake is 37.1 km2, and the maximum depth is 57 m. The heat budget in the melting season was dominated by the radiation balance, and turbulent heat fluxes were small except that occasionally sensible heat flux was large. The strong solar radiation leads to internal melting, and under the ice water warms up resulting in convective mixing. The fractions of surface melting, internal melting and bottom melting depend on weather and structure. Radiation transfer through the ice was measured using photo-synthetically active radiation (PAR) irradiance sensors. The data obtained was also used as the reference of mathematical model development. In this model ice and liquid water can coexist in a grid cell when the temperature is at the melting point. The model is able to predict melting and deterioration of lake ice but the solar radiation sub-model needs further work. The output provides ice thickness and porosity, which tell of evolution of ice strength in the melting season.
Year: 2018