SURFACE WAVE EFFECTS ON THE UPPER OCEAN RESPONSES TO FAST-MOVING STORMS

Abstract

Numerical models generally have problems in the prediction of storm intensities due partially to inadequate simulations of the upper ocean mixing and related upper ocean responses to storms. Although ocean waves have been regarded as essential roles in the upper ocean mixing, their effects are not always explicitly incorporated in model simulations. This study is to examine the surface wave effects on upper ocean responses to fast-moving storms based on both observations and numerical simulations. A one-dimensional depth-dependent ocean turbulence model known as GOTM is modified by incorporating surface gravity wave effects including wave breaking, Langmuir circulation and Coriolis-Stokes force. This newly-modified model is applied to simulate the upper ocean responses to Hurricane Arthur (2014) and Hurricane Felix (1995). The model results demonstrate that the incorporation of wave effects, particularly the wave breaking and Langmuir circulation, improves GOTM simulations. Wave effects improve the simulations of the upper ocean thermal responses by significantly enhancing the upper ocean cooling and deepening the simulated mixed layer depth, which leads to better agreement with observations. Wave effects also significantly improve the simulation of near-inertial current amplitudes especially near the base of the ocean mixed layer. With the incorporation of wave effects, the near-inertial energy is transported more efficiently to deeper layers.