DEVELOPMENT OF A PREDICTION SYSTEM FOR RADIONUCLIDE DISPERSION IN FUKUSHIMA COAST

Abstract

 A downscaling oceanic dispersal modeling system has been developed. The system consists of double nested ROMS embedded in the MOVE assimilative reanalysis product and oceanic radionuclides dispersion model SEA-GEARN-FDM. The developed submesoscale eddy-resolving model is applied to reanalyses of the Fukushima accident occurred in March 2011. Model validations with satellite and in-situ data agreed well. The finest resolution model performed well between three models with different grid resolutions, suggesting that submesoscale eddies and associated vertical flows in the upper layer are substantial to three-dimensional behavior of the radionuclide. A diagnostic vertical ¹³⁷Cs flux analysis demonstrates that ageostrophic secondary circulations induced by submesoscale eddies promote seasonaly-varying subduction of the ¹³⁷Cs enhanced in spring, namely, immediately after the accident.