Bottom buoyancy layer in an ice-covered lake

Abstract

Field data on temperature and salt content structure in the vicinity of the bottom boundary in an ice-covered lake are analyzed. A bottom boundary layer is identified, characterized by rapid increases in both temperature and salt concentration and having a thickness of ~1 dm with respect to temperature and 2-4 cm with respect to salt content. A simple analytical model of the temperature distribution in the near-bottom layer and the associated downslope flow of the heavier water is proposed. The model describes satisfactorily the temperature field in the near bottom layer. The corresponding modeled advective velocities are near 1 mm s-1 in early winter and 1 order of magnitude lower in late winter, the latter values agreeing well with observations in other lakes.