Salinity Exchange through the Quasi-Stationary Jet from the Subtropical to the Subpolar Pacific Ocean

Abstract:

It is known that a quasi-stationary jet-like current [referred to as J1 in Isoguchi et al. (2006)] flows along the northern part of the Kuroshio/Oyashio mixed water region in the western Pacific Ocean. Observations (Isoguchi et al. 2006, Wagawa et al. 2014) have shown that the jet transports saline water in the subtropical Pacific Ocean to the subpolar region. To investigate how the subtropical water is transported through the quasi-stationary jet, numerical particle were tracked using a high resolution ocean reanalysis dataset, the Japan Coastal Ocean Predictability Experiment (JCOPE2). Particle released from the region near the quasi-stationary jet (152-158°E, 42-45°N) are tracked for one year from 15th day of every month and every year (1993-2013) with daily velocity of the JCOPE2 reanalysis at 30 m depth. Backward particle tracking shows that the particles near the jet come from wide southward area, which suggests that eddies are important in the transport process of the saline subtropical water. The number of particles that go back to the region south of 36°N within one year varies greatly in time, from 0.002% to 20% of the total particles. Forward particle tracking shows that the part of particles flows northeastward, which indicates the western subpolar gyre, while part of the particles are trapped in another jet-like current [referred to as J2 in Isoguchi et al. (2006)].