Measurements of Sea-State Variations Across Oceanic Fronts Using Laser Profilometry

Abstract

As part of the Grand Banks Experiment in May 1979, airborne laser profilometer measurements of the ocean wave field were made across a large cold-water extrusion situated over the Newfoundland Ridge. The feature is actually an extension of the Labrador Current which is bordered on the west side by the Gulf Stream and on the east side by the North Atlantic Current. Star-shaped flight patterns were flown over the fronts on each side of the cold-water feature. A graphic technique was applied to the apparent wavenumber spectra in order to determine the changes in wave energy, wavelength and direction of propagation of the dominant wind-wave and swell components as they move across the fronts. At the western front, the sea state increased abruptly and the results indicate that wave-current interactions were the most important mechanism for wave modification although boundary-layer effects were present and increased wave breaking was observed. At the eastern front, changes in the swell are compared to theoretical predictions and are in very close agreement.