Island Barrier Effects on Sea State as Revealed by a Numerical Wave Model and DMSP Satellite Data

Abstract

Island barrier effects on the state of the sea in the lee of islands have been studied by means of a numerical wave prediction model and by examination of data from sensors of the Defense Meteorological Satellite Program (DMSP), the Synchronous Meteorological Satellite (SMS), and the Earth Resources Technology Satellite (ERTS). Visual indications of calm areas in the lee of the Lesser Antilles, evidenced by a marked reduction in the satellite-observed sunglint at selected sun angles, are verified by the results from the numerical wave model; other lee reflective patterns correspond to areas of changed sea state. These results indicate that a reduction in the swell height, alteration of the period, and reorientation of the swell direction, in many instances lol)g distances to the island's lee, are responsible for the satellite-observed reflective patterns noted. The additional phenomena of bow waves and wind-induced oceanographic eddies are also examined, and some evidence of their occurrence and detection is presented.