Simulation of atmospheric radiocesium (¹³⁷Cs) from Fukushima nuclear accident using FLEXPART-WRF driven by ERA5 reanalysis data

This study investigates short-range atmospheric transport of radiocesium (137Cs) after Fukushima nuclear accident using the Weather Research and Forecasting (WRF) model and the Lagrangian particle dispersion FLEXPART-WRF model. The most up-to-date ERA5 reanalysis dataset is used as initial and boundary condition for the WRF model for every hour. Four experiments were carried out to examine the sensitivity of simulation results to micro-physics parameterizations in the WRF model with two configured domains of 5 km and 1 km horizontal resolution. Compared with observation at Futaba and Naraha station, all experiments reproduce reasonably the variation of 137Cs concentration from 11/03 to 26/03/2011. Statistical verification as shown in Taylor diagrams highlights noticeable sensitivity of simulation results to different micro-physics choices. Three configurations of the WRF model are also recommended for further study based on their better performance among all.