In this special issue, we present key findings regarding
physical and biogeochemical processes in the Okhotsk–Pacific
system and the mechanisms that determine them (Fig. 2).
Our studies clearly reveal that the Amur River discharge influences
the distributions of materials (Fe and organic matter in
our studies) and that transport of these materials in the surface
layer by the ESC influences the biological systems in the
Sea of Okhotsk. The Amur River discharge also strongly influences a wide area of the northwestern continental shelf and
the materials in the surface sediments on the shelf. Materials
derived from sediments on the continental shelf are subsequently
transported in DSW and OSIW, driven by sea-ice production
and water ventilation, and pass through straits of the
Kuril Islands chain into the intermediate water masses of the
western North Pacific. Our observational studies also revealed
that intensive mixing redistributes the materials in OSIW as
the water passes the Kuril Island chain, and this mixing is
the predominant process determining the chemical properties
of subarctic Pacific water and NPIW. These material transport
and mixing processes explain the enhanced phytoplankton
growth and biogeochemical cycling in the western subarctic
Pacific Ocean (Nishioka et al., 2013). Thus, the Sea of Okhotsk
plays a pivotal role in overturning circulation and biogeochemical
cycling in the North Pacific.