Simulation of Water Circulations and Chloride Transports in Lake Superior for Summer 1973

Abstract

The mean water circulations of Lake Superior during June-September, 1973, is obtained by hydrodynamical modeling. The time interval covers most of the stratification period during which the temperature data have been adequately collected and analysed. The computed results show reasonable agreement with observed current meter readings. In particular, the generally counterclockwise circulation and some features of the Keweenaw current are obtained in the results. A computed map showing the frequent upwelling and downwelling zones is also given. These zones are often referred to in the description of the physical, chemical and biological regimes of the lake. The computed currents provide adequate description of the advective transports during the period. By parameterizing the turbulent diffusion in an advection-diffusion model, it is shown that the formulation proposed in previous studies appears to be also applicable for simulating the chloride transport in Lake Superior. Based on these studies, the mixing times of conservative materials have been estimated to be about 2 to 3 years for Lake Superior, depending on the location of the source.