Wentao Liu, Applied Mathematics, University of Waterloo
Three Dimensional Hydrodynamic Modeling of Lake Erie
In this thesis we investigate physical processes in Lake Erie from two perspectives: climate change impacts on thermal structure and dissolved oxygen (DO) and small-scale eddy dynamics generated by the internal Kelvin wave propagation. A 3D hydrodynamic and ecological coupled model ELCOM-CAEDYM, validated by field data collected in 2008, is used to investigate the responses of thermal structure and DO to possible changes in air temperature and wind speed. We present an original method to define spatially and temporally varying regions for the epilimnion, thermocline, and hypolimnion. Four metrics are selected to quantify the thermal structure responses: mean epilimnion temperature, mean hypolimnion temperature, onset and breakdown of stratification, and thermocline depth. In DO studies we conclude that three factors related to lake hydrodynamics have strong influences on the hypolimnetic hypoxia: water temperature, stratification duration, and hypolimnion thickness. The present results show the potential for complicated and interactive effects of climate forcing on important biogeochemical processes in Lake Erie as well as other large mid-latitude lakes. Taking advantage of high performance computing, the generation of eddies when a baroclinic Kelvin wave propagates past a peninsula is studied using the MITgcm. With the finer resolution we explore more small-scale processes that cannot be resolved in the course resolution. The eddy dynamics are studied in detail in both the idealized lake and Lake Erie. This work presents a first attempt at simulating small-scale hydrodynamic processes in large lakes and contributes to our understanding of how energy is moved from large scales to smaller scales.