AN ANALYSIS OF OCEAN SWELLS “YORIMAWARI-NAMI” BASED ON THE SWELL INDEX

Abstract

 In this study, we propose a Swell Index (SI) to define the ocean swells quantitatively in the wave field. SI can be widely applied to decompose the measured wave spectra into windsea and swell components. Based on an analysis of wave fields in the Toyama bay, we show that the SI can clearly separate the swell energy from total one and the use of SI successfully explains the characteristic wave fields in the bay. We also examine wave ray pattern which is significantly modulated by the bottom-induced refraction. We conclude that SI is a useful metric to quantify the swells for practical purposes because of their simplicity and robustness.