Thermal Regime of Ice-Covered Lakes

Definition

Thermal regime of ice-covered lakes considers the heat fluxes to and from a water body without direct contact with the atmosphere, the temperature distribution over the depth, and how it changes during the ice-covered period.

In the autumn after the surface water is cooled to 4°C and the water has turned over, the warmest water in a lake is that of the highest density. The surface water is colder than the bottom water. If there is a very cold period shortly after turnover, a wind-sheltered lake may freeze-over when the water not far from the surface and downward is still 4°C. In another year, the turnover may be followed by an extended windy period with air temperatures fluctuating around 0°C, resulting in a reduction of the lake water temperature down to considerable depths. The initial temperature profile after freeze-over is quite different for the two situations.

Once a lake has a stable ice cover, the lake water is more or less insulated from the atmosphere. The heat...