Simulating the thermal behavior in Lake Ontario using EFDC

The thermal behavior of Lake Ontario (spring warming, thermal bar formation, and summer stratification) is simulated using the three-dimensional thermo-hydrodynamic model, Environmental Fluid Dynamics Code (EFDC). The model is forced with hourly meteorological data from weather stations around the lake and flow data from Niagara and St. Lawrence Rivers. The simulation is performed from April to July 2011 on a curvilinear grid, with cells approximately 2 × 2 km2 and bathymetry interpolated onto the grid. We implement model improvements by (a) updating the evaporation algorithm to ensure accurate simulation of evaporation rates and latent heat fluxes and (b) specifying appropriate solar radiation attenuation coefficients to ensure sufficient absorption of incoming solar radiation by the water column. The study also calibrated horizontal and vertical mixing coefficients. Results show that the model accurately simulated the overall surface temperature profiles with RMSEs between 1 and 2 °C and the vertical temperature profiles during the lake mixed phase with RMSEs < 0.5 °C. Overall, the modified EFDC model successfully replicated thermal bar evolution.