Numerical Modelling of the Effects of the Gulf Stream on the Wave Characteristics

Abstract

The influence of the Gulf Stream on the wind wave characteristics is investigated. Wave–current interaction inside the current field can result in significant inhomogeneities of the wave field that change the wave spectrum and wave statistics. This study relies on regional realistic simulations using high resolution in time, space and in the spectral space that allow to solve small scale features of the order of 5 km. Wave model simulations are performed with and without ocean currents to understand the impact of the Gulf Stream. Modelled wave spectra are examined along the main axis of the Gulf Stream, and also along a transect that crosses the current. The behavior of significant wave height (Hs), the current speed, as well as the mean wave propagation and the current direction are analyzed at the selected transect locations. It is shown that inside the current the spectral wave energy grows if the wave and the current are aligned and opposed which result in a very peaked and elongated spectrum. The Gulf Stream causes a widening of the spectrum angular distribution. The results indicate that the Hs increases with the current velocity once the waves are inside the Gulf Stream. Most of the time, waves travelled in opposite direction to the current that flows from the SW to the NE, which could explain why inside the Gulf Stream waves are high. The validation of the numerical simulations is performed for Hs using different wave buoy data available in the study region for the winter period of 2019. In addition, one-dimensional wave spectra measured by an NDBC (National Data Buoy Center) wave buoy are compared with the WAM (Wave Advanced Modeling) modelled 1d spectra showing a good correlation. Accounting for ocean currents improves the quality of the simulated results, which is more realistic than only considering waves.