Hindcast Validation of Shallow Water Wave Processes in the Great Lakes using Unstructured Spectral Models

The modeling of waves in shallow environments is challenging because of irregular coastlines and bathymetry, as well as complicated meteorological forcing. This paper focuses on studying wave growth, propagation and dissipation on flexible unstructured meshes developed for all five of the Great Lakes. These efforts are aimed at the development of a coupled operational wave-surge model built from WAVEWATCH III and FVCOM. In order to analyse the requirements for this model, we ran the 3rd-generation spectral wave model WAVEWATCH III 4.18 on a series of 2D unstructured meshes. The meteorological input forcing fields are 1km/4km/12km WRF wind provided by the National Weather Service Forecast Office in Detroit. The 12km wind forcing is comparable to the current operational NAM wind. Upcoming NAM systems will feature a resolution of 4km. The convection-resolving 1km resolution provides further detail for sensitivity testing. Average coastal mesh resolutions of ~2000m ("low res"), ~200m ("high res") and ~100m ("extra-high res") were tested. We conducted tests for 5 short-term (storm length) test cases and 3 long-term (seasonal) test cases. Comparison of Ardhuin 2010 physics package and Filipot-Ardhuin 2012 physics package will be discussed. Time series, spatial plots and statistical analysis are provided. In addition to this wave physics analysis, we also applied the widely-used ADCIRC+SWAN to evaluate the numerical performance in the context of wave-circulation coupled modeling.