Lake Erie Thermocline Model Results: Comparison with 1967–1982 Data and Relation to Anoxic Occurrences

A one-dimensional thermocline model is presented which is used to estimate daily vertical temperature distributions, thermal layer thicknesses, thermal interface depths, and vertical diffusion. Comparison of computed temperature with observed vertical profile data (1967–1982) for the three basins shows good agreement. The median relative error between observed and computed mean temperature for the central basin hypolimnion is approximately 5 percent. These computed temperature profiles are used to derive statistical distributions which can be useful for designing sampling frequencies in the Great Lakes Surveillance Program. In particular, analyses are presented on the frequency of occurrence of certain thermal structures particularly favorable for the development of anoxia. It is found that, for a hypolimnion thickness of less than 4-m depth and a turbulent diffusivity less than 1 cm 2/s, there is a high likelihood of anoxia development in the central basin of Lake Erie.