Optimum interpolation analysis of basin-scale 137Cs transport in surface seawater in the North Pacific Ocean

A basin-scale analysis reveals that cesium-137 (¹³⁷Cs) from nuclear tests at Bikini and Enewetak Atolls, along with global fallout, was transported eastward by the Kuroshio and North Pacific Currents, accumulating in the eastern North Pacific until 1967 before declining due to southward transport. The study used optimum interpolation (OI) analysis to map ¹³⁷Cs distribution and temporal changes in surface seawater from 1957 onward, uncovering complex circulation patterns, including northward transport of less contaminated water in the western Pacific during the 1970s, indicative of recirculation within the North Pacific Gyre. This work provides critical insights into oceanic tracer dynamics on decadal scales.

Inomata, Y., Aoyama, M., Tsumune, D., Motoi, T., & Nakano, H. (2012). Optimum interpolation analysis of basin-scale 137Cs transport in surface seawater in the North Pacific Ocean. Journal of Environmental Monitoring, 14(12), 3146. https://doi.org/10.1039/c2em30707c