Model intercomparison study for atmospheric Cs from the Fukushima Daiichi Nuclear Power Plant Accident using identical input data

Sato, Yosuke*; Takigawa, Masayuki*; Sekiyama, Tsuyoshi*; Kajino, Mizuo*; Terada, Hiroaki   ; Nagai, Haruyasu  ; Kondo, Hiroaki*; Uchida, Junya*; Goto, Daisuke*; Qulo, D.*; Mathieu, A.*; Evangeliou, N.*; Pisso, I.*; Stohl, A.*; Sheng, F.*; Morino, Yu*; von Schoenberg, P.*; Grahn, H.*; Brnnstrm, N.*; Hirao, Shigekazu*; Tsuruta, Haruo*; Yamazawa, Hiromi*; Nakajima, Teruyuki*

An intercomparison of atmospheric dispersion model targeting on the physical process of Cs released from the Fukushima Daiichi Nuclear Power Plant was conducted. Twelve atmospheric models participated in this project. To exclude the uncertainties of the model result due to the emission inventory and meteorological data, all models used the same emission and meteorological data. Concentration of Cs from the national suspended particle matter monitoring network and the deposition density by the aircraft were used for the comparison between results of the model and observation. Our analyses elucidated the figure of merit in space (FMS) of the model ensemble mean was improved from a previous model intercomparson about the accumulated deposition. The model ensemble mean captured approximately 36% of the observed high concentration. The inter-model spread of the capture rate was from 8% to 38%. It was originated from the difference in deposition and diffusion processes among the models.