Skip to Content

Under-ice stratification and convection in a large dimictic lake

We monitored under ice temperature, dissolved oxygen, and conductivity conditions over winter into early spring in the winters of 2015, 2016 and 2017 in Lake Simcoe, a large dimictic ice-covered lake. In early winter, there is significant warming of the lower half of the water column, resulting in an inverse thermal stratification. In late winter as the ice became more transparent, the increase in light causes cold surface waters below 4 degrees to warm up, driving deep convection underneath the ice. Thorpe scale calculations and mixing efficiency estimates suggest that differences in ice coverage and stratification critically influences the the intensity of convection and mixing rates. I will also briefly explain the implications of winter dynamics on dissolved oxygen and salt concentrations, which are two pressing issues in Lake Simcoe.