title: Optimum interpolation analysis of basin-scale ¹³⁷Cs transport in surface seawater in the North Pacific Ocean.
abstract: ¹³⁷Cs is one of the conservative tracers applied to the study of oceanic circulation processes on decadal time scales. To investigate the spatial distribution and the temporal variation of ¹³⁷Cs concentrations in surface seawater in the North Pacific Ocean after 1957, a technique for optimum interpolation (OI) was applied to understand the behaviour of ¹³⁷Cs that revealed the basin-scale circulation of Cs ¹³⁷Cs in surface seawater in the North Pacific Ocean: ¹³⁷Cs deposited in the western North Pacific Ocean from global fallout (late 1950s and early 1960s) and from local fallout (transported from the Bikini and Enewetak Atolls during the late 1950s) was further transported eastward with the Kuroshio and North Pacific Currents within several years of deposition and was accumulated in the eastern North Pacific Ocean until 1967. Subsequently, ¹³⁷Cs concentrations in the eastern North Pacific Ocean decreased due to southward transport. Less radioactively contaminated seawater was also transported northward, upstream of the North Equatorial Current in the western North Pacific Ocean in the 1970s, indicating seawater re-circulation in the North Pacific Gyre.
authors.affiliation: Atmospheric Research Department, Asia Center For Air Pollution Research, Niigata, Japan. inomata@acap.asia
authors.forename: Y
authors.initials: Y
authors.lastname: Inomata
authors.forename: M
authors.initials: M
authors.lastname: Aoyama
authors.forename: D
authors.initials: D
authors.lastname: Tsumune
authors.forename: T
authors.initials: T
authors.lastname: Motoi
authors.forename: H
authors.initials: H
authors.lastname: Nakano
mesh_terms: D002588:Cesium Radioisotopes / Q000032:analysis*; D008956:Models, Chemical; D010140:Pacific Ocean; D011834:Radiation Monitoring / Q000379:methods*; D011847:Radioactive Fallout / Q000032:analysis* / Q000706:statistics & numerical data; D012623:Seawater / Q000737:chemistry*; D014872:Water Movements; D014875:Water Pollutants, Radioactive / Q000032:analysis*
chemical_list: D002588:Cesium Radioisotopes; D011847:Radioactive Fallout; D014875:Water Pollutants, Radioactive