Some Aspects of Great Lakes Physics of Importance to Biological and Chemical Processes

Abstract

This is a discussion of some aspects of the physical behavior of the Great Lakes written for scientists with backgrounds in disciplines other than physics. The basic physical characteristics of Great Lakes basins are summarized. These characteristics are determined by the facts that (i) the basins are closed, (ii) the basins are large enough so that the Coriolis force is an important component of their dynamics, (iii) the principal source of mechanical energy is the wind, and (iv) the basins are vertically stratified in summer. Discussion of large-scale horizontal motions includes both currents and diffusion. The advection–diffusion equation is used as a framework for a discussion which includes a summary of the basic problem confronting hydrodynamic modellers, the parameterization of turbulence phenomena in terms of mean flow variables. Vertical transfer processes are considered, notably the measurement of vertical fluxes of heat and momentum and the computation of eddy diffusion coefficients, the prediction of thermal structure in terms of net surface wind stresses and heat fluxes, and the interactions of waves, currents, and turbulence in the thermocline. The dynamical structure of the coastal zone is outlined, and the review concludes with recommendations for future work on the understanding of vertical turbulent transports, the climatology of Great Lakes coastal zones, and an operational approach to verifying and improving numerical models of lake circulation.