Influence of Okhotsk Sea intermediate Water on the Oyashio and North Pacific intermediate Water

[1] The volume transport between the Okhotsk Sea and western subarctic North Pacific is estimated on the basis of direct current measurements made by a lowered acoustic Doppler current profiler (LADCP) and hydrographic data taken in August and September 1999 near the Kuril Islands. The estimated southwestward Oyashio transport was 11–12 Sv (=106 m3/s) in the density range of 26.7–27.4 σθ. The net transport of the Okhotsk Sea water (OSW) was 3.4 Sv, of which 1.3 Sv was coming out through the Kruzenshterna Strait and 2.1 Sv was coming out through the Bussol' Strait. A bidirectional flow was observed in the Bussol' Strait: inflow in the northern part of the strait and outflow in the southern part; 0.6 Sv of OSW recirculated along the western subarctic gyre. The remaining 2.8 Sv of OSW could contribute to the formation of North Pacific Intermediate Water as a cross-Subarctic Front transport along the coast (1.4 Sv) and across the offshore SAF (1.4 Sv). The production rate of the Dense Shelf Water (DSW) through sea ice formation was estimated to be at least 1.1 Sv. When the intermediate OSW is formed through the mixing between cold and fresh DSW and warm and salty waters from the Pacific and Japan Sea, 16.8 TW (=1012 W) of heat, 0.007 Sv of freshwater, and 2.3 × 105 kg/s of salt are exchanged. The net flux of oxygen and anthropogenic CO2 (ex-CO2) from the Okhotsk Sea into the Pacific in 26.7–27.4 σθ is estimated to be 10.5 and 2.1 Tmol/yr (0.025 GtC/yr), respectively. The ex-CO2 transported by OSW accounts for about 10% of the accumulation of ex-CO2 in the subarctic and subtropical Pacific.