Circulation and properties of deepwater in the Japan Sea inferred from distribution of multiple tracers

Aramaki, Takafumi*; Otosaka, Shigeyoshi  ; Takahata, Naoto*; Isoda, Yutaka*; Kuma, Kenshi*; Senju, Tomoharu*

Deep part of the Japan Sea ( 2000m depth) consists of seawater with uniform salinity and temperature. This structure complicated us to understand the transport processes of the deepwater circulation in the sea. By the Japan Sea Expeditions carried out by JAEA from 1997 to 2002, the authors measured isotopic ratio of radiocarbon in seawater as a tracer of seawater movement. As a result, it has been inferred that the deep water is formed in the plural regions of the sea and that the northwestern region is primary region of deep water formation. In the present study, we obtained data of tritium concentration and isotopic ratio of helium as additional indicators, and discussed the detailed deepwater circulation to describe another origin of the deep water.