Inverse estimation of source parameters of oceanic radioactivity dispersion models associated with the Fukushima accident

[摘要] With combined use of the ocean–atmosphere simulation models and fieldobservation data, we evaluate the parameters associated with the totalcaesium-137 amounts of the direct release into the ocean and atmosphericdeposition over the western North Pacific caused by the accident ofFukushima Daiichi nuclear power plant (FNPP) that occurred in March 2011.The Green's function approach is adopted for the estimation of twoparameters determining the total emission amounts for the period from 12March to 6 May 2011. It is confirmed that the validity of the estimationdepends on the simulation skill near FNPP. The total amount of the directrelease is estimated as 5.5–5.9 × 10¹⁵ Bq, while that of theatmospheric deposition is estimated as 5.5–9.7 × 10¹⁵ Bq, whichindicates broader range of the estimate than that of the direct releaseowing to uncertainty of the dispersion widely spread over the western NorthPacific.

[学科分类] 地球化学与岩石