We demonstrate the transport pathways of Alaskan Stream water in the eastern subarctic Pacific and the eastern Bering Sea from October 1, 1994 to September 12, 2016 with the help of altimetry-based Lagrangian maps. A mesoscale eddy activity in the Alaskan Stream region and the eastern Bering Sea is shown to be relatedwith the wind stress curl in winter. The mesoscale dynamics may determine not only lower-trophic-level organism biomass but also salmon abundance/catch in the study area.

A Lagrangian method is developed to track, document and analyze the origin and history of water masses in ocean features. Simulating synthetic tracers in the altimetry-derived velocity field, we identify and track the mesoscale eddies which have been sampled in the cruises after the Fukushima accident and estimate their risk of being contaminated by radionuclides. The simulated results are shown to be in a good qualitative correspondence with in situ measurements.

Transport of subtropical waters in the Japan Sea is simulated based on altimeter data. Preferred transport pathways across the Subpolar Front are found. The cross-frontal transport is shown to be inhomogeneous with gates and barriers whose locations are determined by a local velocity field. The gates open due to suitable dispositions of mesoscale eddies facilitating propagation of subtropical waters to the north. There are forbidden zones where the northward transport has not been observed.