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.

Effects of lake size, water clarity, and climatic variability on mixing depths in Canadian Shield lakes

“…Boyce (1974) summarized the types of motions that occur in lakes, along with the scales where each becomes significant. Out of the eight classes of motion that depend on horizontal scale, six are significant only at length scales of 10 km and larger (i.e.…”

Applying phosphorus loading models to embayments1

“…4. The resulting diffusion coefficient of about 5 X lo5 cm2 * s-l is generally of the order of horizontal diffusion coefficients for this scale of motion (Boyce 1974). An application of Eq.…”

Observations of small‐scale spatial patterns in phytoplankton populations1

“…Although this eddy was composed of water quite different from that of Coote's Paradise, we would expect it to be mixed rapidly into the surrounding water mass so that the phytoplankton populations within the eddy would be dispersed before significant competitive interactions could take place. The magnitude of horizontal diffusivity in the surface waters of the Great Lakes and of the oceans appear to be comparable (Boyce 1974;Ontario Min. Environ.…”

“…Horizontal patchiness is harder to explain, and many limnologists have assumed that the surface mixed layer of lakes and oceans was homogeneous ( Hutchinson 1961). Indeed the horizontal eddy diffusivity ( KH) exceeds the vertical eddy diffusivity ( KZ) by at least an order of magnitude (Boyce 1974); horizontal patchiness, however, appears to be the rule rather than the exception.…”