Atmospheric modeling of Cs plumes from the Fukushima Daiichi Nuclear Power Plant; Evaluation of the model intercomparison data of the Science Council of Japan

Kitayama, Kyo*; Morino, Yu*; Takigawa, Masayuki*; Nakajima, Teruyuki*; Hayami, Hiroshi*; Nagai, Haruyasu  ; Terada, Hiroaki   ; Saito, Kazuo*; Shimbori, Toshiki*; Kajino, Mizuo*; Sekiyama, Tsuyoshi*; Dider, D.*; Mathieu, A.*; Qulo, D.*; Ohara, Toshimasa*; Tsuruta, Haruo*; Oura, Yasuji*; Ebihara, Mitsuru*; Moriguchi, Yuichi*; Shibata, Tokushi*

We compared seven atmospheric transport model results for Cs released during the Fukushima Daiichi Nuclear Power Plant accident. All the results had been submitted for a model intercomparison project of the Science Council of Japan in 2014. We assessed model performance by comparing model results with observed hourly atmospheric concentrations of Cs, focusing on nine plumes over the Tohoku and Kanto regions. The results showed that model performance for Cs concentrations was highly variable among models and plumes. We also assessed model performance for accumulated Cs deposition. Simulated areas of high deposition were consistent with the plume pathways, though the models that best simulated Cs concentrations were different from those that best simulated deposition. The ensemble mean of all models consistently reproduced Cs concentrations and deposition well, suggesting that use of a multimodel ensemble results in more effective and consistent model performance.