Numerical Modeling of Coastal Storms for Ice-Free and Ice-Covered Lake Erie

Lake Erie is the shallowest among the Great Lakes. Because of its shallow depth and because predominant wind direction in the area is along the lake's longitudinal axis, eastern and western Lake Erie experience significant storm surge that are usually followed by seiches. The lake warms in summer and quickly freezes over in winter when it often develops extensive surface ice. The surface ice, in turn, can modify wind setup and waves and even hinder wave propagation in areas where the surface ice is densely concentrated. In the following, a coupled numerical model for storm surge and wave is utilized for the simulation of Lake Erie coastal storms under ice-free and ice-covered lake conditions. Six extreme events, affecting both eastern and western Lake Erie, are selected for presentation here. A high resolution mesh is developed using the National Oceanic and Atmospheric Administration (NOAA) bathymetric data. The wind and pressure fields are developed for the selected storms based on the Climate Forecast System Reanalysis hindcast data and are used in the model as the primary forcing mechanism for the extreme events. For winter storms, the model is provided with temporally and spatially varying ice fields developed based on the NOAA Ice Atlas. Quantitative comparisons of spatial and temporal variations of simulated and measured storm surge and wave fields are presented. Furthermore, for the winter storms, the effect of ice cover on storm surge is assessed by comparing the model results for storm surge with actual ice-covered condition and the hypothetical ice-free condition.