Factors Influencing Model Skill for Hindcasting Shallow Water Currents during Hurricane Andrew

Abstract

Hurricane Andrew made landfall in the Gulf of Mexico after crossing directly over several moored current meter arrays deployed on the Louisiana?Texas shelf. The resulting three-dimensional current, temperature, and salinity time series are used in a quantitative analysis of the factors affecting the hindcast skill of ocean circulation models. This paper describes parameters for quantifying a model?s skill at matching both maximum currents and time series at specific locations and depths. It then briefly discusses the following factors with respect to currents hindcast with the Princeton Ocean Model: 1) model domain size; 2) horizontal resolution, including the bathymetry and coastline; 3) vertical resolution (i.e., number of model levels); 4) the surface drag formulation;5) the bottom drag coefficient; 6) turbulent mixing parameters and sources of turbulence; and 7) the initial temperature field. Model performance is found to be most dependent on parameters within the turbulent energy closure scheme and the initial temperature and salinity distributions. The best overall model performance is gained by adjusting one of the closure scheme coefficients (B1) that decreases turbulence dissipation (and increases mixing where a density gradient exists). Results incorporating wave breaking and a depth-dependent initial temperature field, however, are also reasonable, and differences between the model skill parameters are insufficient to determine which approach is preferable.