TRANSPORT PROCESSES AROUND THE IZU-CHAIN ISLANDS INVESTIGATED WITH A LAGRANGIAN PARTICLE TRACKING MODEL

Abstract

 This study investigated mass transport and dispersion around Izu-chain islands off the Japan mainland using 3-D Lagrangian particle tracking simulations modeled in a high-resolution reginal ocean modeling system (ROMS). The Kuroshio, eddies and tides largely influence physical processes in the study area. Details of transport processes involving the Kuroshio, eddies and tides have not been understood well. However, these processes are important for understanding oceanic environments and ecosystems in the North Pacific Ocean. The vorticity is enhanced by the tidal forcing in the whole study area. The tidal forcing enhances the horizontal diffusion of particles within a two-days scale. By contrast, in the longer time scale than two days, the dispersion of particles is suppressed by the tidal forcing, because large scale motions are suppressed by tides. The frequency spectrum of the particle velocity shows semi-diurnal peaks and high frequency (low frequency) is enhanced (decreased) by the tidal forcing. The tidal forcing promotes high frequency and sub-mesoscale eddies and suppresses low frequency and large scale motions.