Simulation of the formation and propagation of the thermal bar on Lake Ontario

Computer-based, mathematical models that simulate spatially distributed and time dependent environmental processes are increasingly recognized to provide diagnostic and productive outputs for the assessments of environmental factors. Mathematical models have been utilized since 60\u27s to study the water quality, the circulation structure and the seasonal changes of large water bodies such as the Great Lakes. Analysis of changes in water quality related to seasonal cycles such as the formation and the propagation of the thermal bar requires spatial and temporal models, with high resolution. The overall objective of this study was to integrate geo-referenced site-specific spatial data to a 3D hydrodynamic model (ALGE) and compare the outputs with geo-referenced remotely sensed thermal imagery. The motivation of this work is based on the idea that the spatial data provides a significant advantage of equipping the model with site specific data to manipulate site specific circulation patterns. Further since the input is geo-referenced and site specific, the output can be directly compared to geo-referenced remotely sensed imagery for model validation. Thus, the aspect of integration of spatial data to hydrodynamic models is an obvious and promising approach to study lake-wide hydrodynamic processors and seasonal changes. A specific objective of the study was to examine how different spatial patterns and weather conditions influence the formation and the propagation of the thermal bar temporally and spatially. Several preliminary studies were conducted on square lakes and lakes with false bathymetric profiles, and compared with the results of laboratory studies and field surveys. Since the outputs compared well with the literature, bathymetric data of Lake Ontario was integrated to the 3D hydrodynamic model with real time surface and atmospheric weather data. The formation and the propagation of the thermal bar was simulated for the years 1997, 1998, 1999 and 1997 (winter) through 1998(fall). The model was fine tuned by changing the initial conditions and weather data to obtain a good approximation to the surface temperature derived from satellite imagery using the split and dual window technique. The lake was also subjected to different weather conditions to study its influences on the formation and propagation of the thermal bar. The model outputs from case studies as well as comparisons of the model output with satellite imagery and the NOAA forecasting model are discussed