National Water Research Institute, Canada Centre for Inland Waters
867 Lakeshore Rd., Burlington, Ontario, Canada, L7R 4A6

*Corresponding author: william.schertzer@ec.gc.ca

Summary

   A review of key hydrodynamical processes in Lake Erie is presented along with trends, variability, and possible changes. Primary focus is on knowledge gained from past physical limnological observations, modelling, and current state of knowledge on possible changes in currents and circulation which may result from climate warming. The circulation of Lake Erie is shown to be complex, largely because of physiography. Specialized observation programs during stratified and unstratified periods have been successful in identifying large-scale circulation patterns including the occurrence of clockwise and anti-clockwise gyres. Research has also documented inter-basin exchange of water and materials, current oscillations, flushing and diffusion time scales, upwelling, surface waves, and turbulence. Modelling has been particularly useful in helping to simulate the 2- and 3-dimensional flow fields and there have been improvements leading to first generation forecast capability for this lake. Knowledge of the complexities of water movements is found to be important for understanding ecological problems (e.g. fish-kills, hypolimnetic anoxia, etc.). Further improvements in instrumentation such as the acoustic doppler current profiler have shown promise in measurement of flows in the upper reaches of the water column. Recommendations for increased spatial and temporal observation of key meteorological components are presented. More research is required to allow projection of possible changes in Lake Erie hydrodynamical processes which may result from changes in climatic forcing. It is suggested that radical changes in thermal structure (e.g. dimictic to monomictic states) will exert a profound influence on winter circulation and mixing. Further, weaker wind forcing expected from climate change in combination with increased bottom friction due to the presence of mussels may lead to a reduction in the strength of lake circulation and mixing which could have consequences on the biology and chemistry of lake Erie.