Dispersion behavior of Fukushima-derived Cs over the North Pacific with emphasis on its sensitivity to vertical velocity and diffusion.

This study simulated the dispersion of Cs in the North Pacific using a Lagrangian particle model, incorporating basin-wide atmospheric deposition and direct release from the Fukushima accident. Three experiments examined the impact of vertical diffusion and velocity on dispersion behavior. EXP01 and EXP02 assumed zero vertical velocity with different vertical diffusion coefficients (1 × 10 and 2 × 10 m/s, respectively), while EXP03 used a 3-day average vertical velocity and the same diffusion coefficient as EXP01.