BOTTOM BUOYANCY LAYER IN AN ICE-COVERED LAKE

Field data on temperature and salt content structure in the vicinity o f the bottom boundary in an ice-covered lake are analyzed. A bottom bo undary layer is identified, characterized by rapid increases in both t emperature and salt concentration and having a thickness of similar to 1 dm with respect to temperature and 2-4 cm with respect to salt cont ent. A simple analytical model of the temperature distribution in the near-bottom layer and the associated downslope flow of the heavier wat er is proposed. The model describes satisfactorily the temperature fie ld in the near bottom layer. The corresponding modeled advective veloc ities are near 1 mm s(-1) in early winter and 1 order of magnitude low er in late winter, the latter values agreeing well with observations i n other lakes.