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Journal Articles

Deposition and dispersion of radio-cesium released due to the Fukushima Nuclear accident, 2; Sensitivity to aerosol microphysical properties of Cs-bearing microparticles (CsMPs)

Kajino, Mizuo*; Adachi, Koji*; Igarashi, Yasuhito*; Satou, Yukihiko; Sawada, Morihiro*; Sekiyama, Tsuyoshi*; Zaizen, Yuji*; Saya, Akane*; Tsuruta, Haruo*; Moriguchi, Yuichi*

Journal of Geophysical Research; Atmospheres, 126(1), 23 Pages, 2021/01

 Times Cited Count:2 Percentile:89.67(Meteorology & Atmospheric Sciences)

Journal Articles

A Model intercomparison of atmospheric $$^{137}$$Cs concentrations from the Fukushima Daiichi Nuclear Power Plant accident, phase III; Simulation with an identical source term and meteorological field at 1-km resolution

Sato, Yosuke*; Sekiyama, Tsuyoshi*; Fang, S.*; Kajino, Mizuo*; Qu$'e$rel, A.*; Qu$'e$lo, D.*; Kondo, Hiroaki*; Terada, Hiroaki; Kadowaki, Masanao; Takigawa, Masayuki*; et al.

Atmospheric Environment; X (Internet), 7, p.100086_1 - 100086_12, 2020/10

The third model intercomparison project for investigating the atmospheric behavior of $$^{137}$$Cs emitted during the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident (FDNPP-MIP) was conducted. A finer horizontal grid spacing (1 km) was used than in the previous FDNPP-MIP. Nine of the models used in the previous FDNPP-MIP were also used, and all models used identical source terms and meteorological fields. Our analyses indicated that most of the observed high atmospheric $$^{137}$$Cs concentrations were well simulated, and the good performance of some models improved the performance of the multi-model ensemble. The analyses also confirmed that the use of a finer grid resolution resulted in the meteorological field near FDNPP being better reproduced. The good representation of the wind field resulted in the reasonable simulation of the narrow distribution of high deposition amount to the northwest of FDNPP and the reduction of the overestimation over the area to the south of FDNPP. In contrast, the performance of the models in simulating plumes observed over the Nakadori area, the northern part of Gunma, and the Tokyo metropolitan area was slightly worse.

Journal Articles

Intercomparison of numerical atmospheric dispersion prediction models for emergency response to emissions of radionuclides with limited source information in the Fukushima Dai-ichi Nuclear Power Plant accident

Iwasaki, Toshiki*; Sekiyama, Tsuyoshi*; Nakajima, Teruyuki*; Watanabe, Akira*; Suzuki, Yasushi*; Kondo, Hiroaki*; Morino, Yu*; Terada, Hiroaki; Nagai, Haruyasu; Takigawa, Masayuki*; et al.

Atmospheric Environment, 214, p.116830_1 - 116830_11, 2019/10

 Times Cited Count:4 Percentile:31.32(Environmental Sciences)

The utilization of numerical atmospheric dispersion prediction (NDP) models for accidental discharge of radioactive substances was recommended by a working group of the Meteorological Society of Japan. This paper is to validate the recommendation through NDP model intercomparison in the accidental release from the Fukushima Dai-ichi Nuclear Power Plant in 2011. Emission intensity is assumed to be constant during the whole forecast period for the worst-case scenario unless time sequence of emission is available. We expect to utilize forecasts of surface air contaminations for preventions of inhalations of radioactive substances, and column-integrated amounts for mitigation of radiation exposure associated with wet deposition. Although NDP forecasts have ensemble spread, they commonly figure out relative risk in space and time. They are of great benefit to disseminating effective warnings to public without failure. The multi-model ensemble technique may be effective to improve the reliability.

Journal Articles

Model intercomparison of atmospheric $$^{137}$$Cs from the Fukushima Daiichi Nuclear Power Plant accident; Simulations based on identical input data

Sato, Yosuke*; Takigawa, Masayuki*; Sekiyama, Tsuyoshi*; Kajino, Mizuo*; Terada, Hiroaki; Nagai, Haruyasu; Kondo, Hiroaki*; Uchida, Junya*; Goto, Daisuke*; Qu$'e$lo, D.*; et al.

Journal of Geophysical Research; Atmospheres, 123(20), p.11748 - 11765, 2018/10

 Times Cited Count:18 Percentile:75.7(Meteorology & Atmospheric Sciences)

A model intercomparison of the atmospheric dispersion of $$^{137}$$Cs emitted following the Fukushima Daiichi Nuclear Power Plant accident was conducted by 12 models to understand the behavior of $$^{137}$$Cs in the atmosphere. The same meteorological data, horizontal grid resolution, and an emission inventory were applied to all the models to focus on the model variability originating from the processes included in each model. The multi-model ensemble captured 40% of the observed $$^{137}$$Cs events, and the figure-of-merit in space for the total deposition of $$^{137}$$Cs exceeded 80. Our analyses indicated that the meteorological data were most critical for reproducing the $$^{137}$$Cs events. The results also revealed that the differences among the models were originated from the deposition and diffusion processes when the meteorological field was simulated well. However, the models with strong diffusion tended to overestimate the $$^{137}$$Cs concentrations.

Journal Articles

Atmospheric modeling of $$^{137}$$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*; et al.

Journal of Geophysical Research; Atmospheres, 123(14), p.7754 - 7770, 2018/07

 Times Cited Count:16 Percentile:75.7(Meteorology & Atmospheric Sciences)

We compared seven atmospheric transport model results for $$^{137}$$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 $$^{137}$$Cs, focusing on nine plumes over the Tohoku and Kanto regions. The results showed that model performance for $$^{137}$$Cs concentrations was highly variable among models and plumes. We also assessed model performance for accumulated $$^{137}$$Cs deposition. Simulated areas of high deposition were consistent with the plume pathways, though the models that best simulated $$^{137}$$Cs concentrations were different from those that best simulated deposition. The ensemble mean of all models consistently reproduced $$^{137}$$Cs concentrations and deposition well, suggesting that use of a multimodel ensemble results in more effective and consistent model performance.

Journal Articles

Resonant photoemission spectroscopy study of impurity-induced melting in Cr- and Ru-doped Nd$$_{1/2}$$A$$_{1/2}$$MnO$$_{3}$$ (A=Ca,Sr)

Kang, J.-S.*; Kim, J. H.*; Sekiyama, Akira*; Kasai, Shuichi*; Suga, Shigemasa*; Han, S. W.*; Kim, K. H.*; Choi, E. J.*; Kimura, Tsuyoshi*; Muro, Takayuki*; et al.

Physical Review B, 68(1), p.012410_1 - 012410_4, 2003/07

A2003-0329.pdf:0.49MB

 Times Cited Count:20 Percentile:68.34(Materials Science, Multidisciplinary)

no abstracts in English

Oral presentation

International comparison of atmospheric dispersion simulations of radioactive materials

Takigawa, Masayuki*; Nagai, Haruyasu; Morino, Yu*; Sekiyama, Tsuyoshi*; Hayami, Hiroshi*; Tanaka, Taichu*; Nakajima, Teruyoshi*; Shibata, Tokushi*

no journal, , 

no abstracts in English

Oral presentation

Intercomparison of atmospheric advection and diffusion prediction by numerical models

Iwasaki, Toshiki*; Nakajima, Teruyuki*; Watanabe, Akira*; Suzuki, Yasushi*; Kondo, Hiroaki*; Morino, Yu*; Terada, Hiroaki; Nagai, Haruyasu; Takigawa, Masayuki*; Sekiyama, Tsuyoshi*

no journal, , 

no abstracts in English

Oral presentation

Environmental dynamics analysis of $$^{137}$$Cs due to the Fukushima Daiichi Nuclear Power Station accident based on the intercomparison of atmospheric dispersion models

Morino, Yu*; Kitayama, Kyo*; Takigawa, Masayuki*; Nakajima, Teruyuki*; Hayami, Hiroshi*; Nagai, Haruyasu; Terada, Hiroaki; Saito, Kazuo*; Shimbori, Toshiki*; Kajino, Mizuo*; et al.

no journal, , 

For the evaluation of the validity and variability of atmospheric transport model results, we compared results of seven models submitted for the model inter-comparison project of Science Council of Japan to simulate $$^{137}$$Cs released from the Fukushima Daiichi Nuclear Power Plant. Model reproducibility was assessed with the observed hourly atmospheric concentrations of $$^{137}$$Cs in Tohoku and Kanto regions. Among nine plumes from 12 to 21 in March 2011, performance of the models was the best for the plume which dispersed over the Kanto region in 15 March. The models generally reproduced the observed $$^{137}$$Cs concentrations in plumes which widely spread inland of Tohoku or Kanto regions. By contrast, the models largely underestimated the observed $$^{137}$$Cs concentrations for the case which passed coastal areas of Japan. Ensemble average of seven models showed reasonable performance for most of plumes, and no individual models reproduced better than the ensemble average.

Oral presentation

Model inter-comparison of atmospheric Cs-137 from the Fukushima Daiichi Nuclear Power Plant accident

Kitayama, Kyo*; Morino, Yu*; Takigawa, Masayuki*; Nakajima, Teruyuki*; Hayami, Hiroshi*; Nagai, Haruyasu; Terada, Hiroaki; Saito, Kazuo*; Shimbori, Toshiki*; Kajino, Mizuo*; et al.

no journal, , 

For the evaluation of the validity and variability of atmospheric transport model results, we compared results of seven models submitted for the model inter-comparison project of Science Council of Japan to simulate $$^{137}$$Cs released from the Fukushima Daiichi Nuclear Power Plant. Model reproducibility was assessed with the observed hourly atmospheric concentrations of $$^{137}$$Cs in Tohoku and Kanto regions. Among nine plumes from 12 to 21 in March 2011, performance of the models was the best for the plume which dispersed over the Kanto region in 15 March. The models generally reproduced the observed $$^{137}$$Cs concentrations in plumes which widely spread inland of Tohoku or Kanto regions. By contrast, the models largely underestimated the observed $$^{137}$$Cs concentrations for the case which passed coastal areas of Japan. Ensemble average of seven models showed reasonable performance for most of plumes, and no individual models reproduced better than the ensemble average.

Oral presentation

2nd atmospheric model intercomparison project for Fukushima Daiichi Nuclear Power Plant Accident on March 2011; 2nd FDNPP-MIP

Sato, Yosuke*; Takigawa, Masayuki*; Sekiyama, Tsuyoshi*; Kajino, Mizuo*; Grahn, H.*; Br$"a$nnstr$"o$m, N.*; von Schoenberg, P.*; Kondo, Hiroaki*; Terada, Hiroaki; Nagai, Haruyasu; et al.

no journal, , 

The second intercomparison of atmospheric model targeting on the radionuclide (i.e. $$^{137}$$Cs) released from the Fukushima Daiichi Nuclear Power Plant (FDNPP) on March 2011 is conducted. Thirteen atmospheric models, which include both the Lagrangian- and Eulerian-based dispersion models, participate in this model intercomparison project (MIP). The purposes of this MIP are to (1) understand the transport process of the radionuclide in atmosphere, (2) estimate the uncertainties in wet and dry deposition process among the models, (3) reveal the essential key processes to reproduce the plume of $$^{137}$$Cs, (4) assess the multi-model ensemble mean, and (5) obtain the knowledge for improving the physical processes of the models. To exclude the uncertainties of the model results originated from the emission inventory, all models used the same emission inventory. The meteorological data with fine spatiotemporal resolution, which was calculated by the Japanese operational weather forecast model coupled with the local ensemble transform Kalman Filter data assimilation system, was applied for all models to reduce the uncertainties originated from the difference in the meteorological field. As well as the comparison among the models, the comparison between the models and in-situ measurement from the national suspended particle matter (SPM) sampling network are conducted. The comparisons between the model results and the SPM data indicate that the $$^{137}$$Cs concentration near the FDNPP transported without precipitation process was relatively well reproduced by using the meteorological data with fine spatiotemporal resolution. On the contrary, $$^{137}$$Cs concentration accompanied with precipitation has large inter-model spread. In the presentation, we will discuss the more detailed analyses about the physical process to determine the $$^{137}$$Cs concentration.

Oral presentation

Deposition and dispersion of radio-cesium; Sensitivity to meteorological models and aerosol properties

Kajino, Mizuo*; Sekiyama, Tsuyoshi*; Igarashi, Yasuhito*; Adachi, Koji*; Zaizen, Yuji*; Sawada, Morihiro*; Satou, Yukihiko; Moriguchi, Yuichi*

no journal, , 

Oral presentation

Model intercomparison study for atmospheric $$^{137}$$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*; Qu$'e$lo, D.*; et al.

no journal, , 

An intercomparison of atmospheric dispersion model targeting on the physical process of $$^{137}$$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 $$^{137}$$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.

Oral presentation

Model intercomparison project for $$^{137}$$Cs from the Fukushima Daiichi Nuclear Power Station Accident using identical meteorological data and source term

Sato, Yosuke*; Takigawa, Masayuki*; Sekiyama, Tsuyoshi*; Kajino, Mizuo*; Terada, Hiroaki; Nagai, Haruyasu; Kondo, Hiroaki*; Uchida, Junya*; Goto, Daisuke*; Qu$'e$lo, D.*; et al.

no journal, , 

no abstracts in English

Oral presentation

Improvement of assessment methods for atmospheric behavior of accidentally discharged hazardous materials by comprehensively analyzing nuclear accident data

Yamazawa, Hiromi*; Oura, Yasuji*; Moriguchi, Yuichi*; Terada, Hiroaki; Sekiyama, Tsuyoshi*; Goto, Daisuke*; Tsuruta, Haruo*

no journal, , 

no abstracts in English

Oral presentation

Model intercomparison project for cesium ($$^{137}$$Cs) from the Fukushima Daiichi Nuclear Power Station Accident using identical meteorological data and source term

Sato, Yosuke*; Takigawa, Masayuki*; Sekiyama, Tsuyoshi*; Kajino, Mizuo*; Terada, Hiroaki; Nagai, Haruyasu; Kondo, Hiroaki*; Uchida, Junya*; Goto, Daisuke*; Qu$'e$lo, D.*; et al.

no journal, , 

no abstracts in English

Oral presentation

Detailed intercomparison of atmospheric transport models using newly obtained concentration data of Cs-137 from the Fukushima Daiichi Nuclear Power Plant Accident

Yamazawa, Hiromi*; Sato, Yosuke*; Adachi, Shinichiro*; Takigawa, Masayuki*; Sekiyama, Tsuyoshi*; Kajino, Mizuo*; Terada, Hiroaki; Kondo, Hiroaki*; Uchida, Junya*; Goto, Daisuke*; et al.

no journal, , 

Cs-137 released from the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident was conducted by 12 models. The present study focuses on differences in the model results of atmospheric Cs-137 concentration of Plume 2, which traveled southward in the morning of 15 March, 2011, in the area 100 to 200 km downwind from FDNPP by using the concentration data recently evaluated from gamma radiation spectral data at monitoring stations (MS data) and those measured from the suspended particulate matter filters (SPM data). Comparison was made from the following aspects: (1) plume arrival time, (2) concentration level, (3) cross-wind surface concentration profile, (4) vertical concentration profile and (5) mass balance of Cs-137 activity including deposition processes. Additional analyses were made also for Plume 4, which traveled over the same area on 16 March under rainy condition.

Oral presentation

Sophistication of dynamics evaluation method for harmful substances in the atmosphere

Yamazawa, Hiromi*; Sato, Yosuke*; Oura, Yasuji*; Moriguchi, Yuichi*; Terada, Hiroaki; Furuno, Akiko; Tsuzuki, Katsunori; Kadowaki, Masanao; Sekiyama, Tsuyoshi*; Adachi, Koji*; et al.

no journal, , 

no abstracts in English

Oral presentation

Intercomparison of atmospheric transport models using 1 km grid meteorological data for the Fukushima Daiichi Nuclear Power Plant Accident

Yamazawa, Hiromi*; Sato, Yosuke*; Sekiyama, Tsuyoshi*; Kajino, Mizuo*; Goto, Daisuke*; Morino, Yu*; Kondo, Hiroaki*; Qu$'e$rel, A.*; Fang, S.*; Takigawa, Masayuki*; et al.

no journal, , 

Following the previous atmospheric transport model intercomparison project (MIP2), a new model intercomparison (MIP3) has been conducted in which, out of 12 models in MIP2, 9 models are participating. The main aim of MIP3 is to examine the effects of using a refined meteorological data with a finer horizontal resolution of 1 km. The horizontal distribution Cs-137 deposition in the eastern part of Honshu Island calculated by the models were compared with the aerial survey results to find that the simple ensemble average of the 9 models was a little worse than that of the 12-model ensemble in MIP2 statistically. However, in the sector in the northwestern direction from the accidental site, the deposition pattern by the MIP3 ensemble is more consistent with the survey result compared with that of MIP2. As for the atmospheric concentrations, although the model performance for the plumes that traveled over wider areas was slightly poorer for MIP3 than MIP2, the MIP3 ensemble generally showed better performance for the plumes that affected the near area in the Hamadori area. This better performance can be attributed to the better representation of topography in the meteorological simulation.

Oral presentation

Third model intercomparison project for $$^{137}$$Cs from the Fukushima Daiichi Nuclear Power Station Accident

Sato, Yosuke*; Sekiyama, Tsuyoshi*; Sheng, F.*; Kajino, Mizuo*; Qu$'e$lo, D.*; Qu$'e$rel, A.*; Kondo, Hiroaki*; Terada, Hiroaki; Kadowaki, Masanao; Takigawa, Masayuki*; et al.

no journal, , 

no abstracts in English

23 (Records 1-20 displayed on this page)