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Moriguchi, Yuichi*; Sato, Yosuke*; Morino, Yu*; Goto, Daisuke*; Sekiyama, Tsuyoshi*; Terada, Hiroaki; Takigawa, Masayuki*; Tsuruta, Haruo*; Yamazawa, Hiromi*
KEK Proceedings 2021-2, p.21 - 27, 2021/12
no abstracts in English
Cs concentrations from the Fukushima Daiichi Nuclear Power Plant accident, phase III; Simulation with an identical source term and meteorological field at 1-km resolutionSato, Yosuke*; Sekiyama, Tsuyoshi*; Fang, S.*; Kajino, Mizuo*; Qu
rel, A.*; Qulo, 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 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 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.
Cs from the Fukushima Daiichi Nuclear Power Plant accident; Simulations based on identical input dataSato, Yosuke*; Takigawa, Masayuki*; Sekiyama, Tsuyoshi*; Kajino, Mizuo*; Terada, Hiroaki; Nagai, Haruyasu; Kondo, Hiroaki*; Uchida, Junya*; Goto, Daisuke*; Qulo, D.*; et al.
Journal of Geophysical Research; Atmospheres, 123(20), p.11748 - 11765, 2018/10
Times Cited Count：40 Percentile：85.28(Meteorology & Atmospheric Sciences)A model intercomparison of the atmospheric dispersion of Cs emitted following the Fukushima Daiichi Nuclear Power Plant accident was conducted by 12 models to understand the behavior of 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 Cs events, and the figure-of-merit in space for the total deposition of Cs exceeded 80. Our analyses indicated that the meteorological data were most critical for reproducing the 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 Cs concentrations.
Sato, Yosuke*; Takigawa, Masayuki*; Sekiyama, Tsuyoshi*; Kajino, Mizuo*; Grahn, H.*; Br
nnstr
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. 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 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 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, 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 Cs concentration.
Cs from the Fukushima Daiichi Nuclear Power Plant Accident using identical input dataSato, Yosuke*; Takigawa, Masayuki*; Sekiyama, Tsuyoshi*; Kajino, Mizuo*; Terada, Hiroaki; Nagai, Haruyasu; Kondo, Hiroaki*; Uchida, Junya*; Goto, Daisuke*; Qulo, D.*; et al.
no journal, ,
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.
Cs from the Fukushima Daiichi Nuclear Power Station Accident using identical meteorological data and source termSato, Yosuke*; Takigawa, Masayuki*; Sekiyama, Tsuyoshi*; Kajino, Mizuo*; Terada, Hiroaki; Nagai, Haruyasu; Kondo, Hiroaki*; Uchida, Junya*; Goto, Daisuke*; Qulo, D.*; et al.
no journal, ,
no abstracts in English
Yamazawa, Hiromi*; Oura, Yasuji*; Moriguchi, Yuichi*; Terada, Hiroaki; Sekiyama, Tsuyoshi*; Goto, Daisuke*; Tsuruta, Haruo*
no journal, ,
no abstracts in English
Cs) from the Fukushima Daiichi Nuclear Power Station Accident using identical meteorological data and source termSato, Yosuke*; Takigawa, Masayuki*; Sekiyama, Tsuyoshi*; Kajino, Mizuo*; Terada, Hiroaki; Nagai, Haruyasu; Kondo, Hiroaki*; Uchida, Junya*; Goto, Daisuke*; Qulo, D.*; et al.
no journal, ,
no abstracts in English
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.
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
Yamazawa, Hiromi*; Sato, Yosuke*; Sekiyama, Tsuyoshi*; Kajino, Mizuo*; Goto, Daisuke*; Morino, Yu*; Kondo, Hiroaki*; Qurel, 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.
Cs from the Fukushima Daiichi Nuclear Power Station AccidentSato, Yosuke*; Sekiyama, Tsuyoshi*; Sheng, F.*; Kajino, Mizuo*; Qulo, D.*; Qurel, A.*; Kondo, Hiroaki*; Terada, Hiroaki; Kadowaki, Masanao; Takigawa, Masayuki*; et al.
no journal, ,
no abstracts in English
Cs emitted from Fukushima Daiichi Nuclear Power Plant; MIPs with identical source term and meteorological dataSato, Yosuke*; Takigawa, Masayuki*; Sekiyama, Tsuyoshi*; Kajino, Mizuo*; Terada, Hiroaki; Nagai, Haruyasu; Kadowaki, Masanao; Kondo, Hiroaki*; Uchida, Junya*; Goto, Daisuke*; et al.
no journal, ,
Two Model Intercomparison of Projects (MIPs) of atmospheric dispersion model targeting on Cs released from Fukushima Daiichi Nuclear Power Plant (FDNPP) on March 2011 were conducted. Both MIPs were conducted using an identical source term of Cs, identical meteorological data, and the same horizontal grid resolution (3 km and 1 km) to exclude the uncertainties of the model originated from them. Our analyses indicated that most of the model well simulated the atmospheric Cs obtained from the operational aerosol sampling of the national suspended particle matter network. Our analyses also indicated that meteorological data were most critical for reproducing the atmospheric Cs events, and the extent of the horizontal diffusion and the deposition were critical if the meteorological field was reasonably simulated. The comparison of the results between the two MIPs elucidated that the fine grid resolution is required to simulate atmospheric Cs in the vicinity of FDNPP, but the use of the fine grid resolution does not always improve the performance of the models especially for areas distant from the FDNPP. The results of both MIPs elucidated that the good performance of some models improved the performance of the multimodel, highlighting the advantage of using a multimodel ensemble.
Cs emitted from Fukushima Daiichi Nuclear Power Plant, and application of MIPs' results for usage in an emergencyYamazawa, Hiromi*; Sato, Yosuke*; Sekiyama, Tsuyoshi*; Kajino, Mizuo*; Fang, S.*; Qurel, A.*; Qulo, D.*; Kondo, Hiroaki*; Terada, Hiroaki; Kadowaki, Masanao; et al.
no journal, ,
The 3rd model intercomparison project (MIP) of atmospheric dispersion model targeting on Cs emitted from Fukushima Daiichi Nuclear Power Plant (FDNPP) in March 2011 were conducted. All participated 9 models used the identical source term and meteorological data as in the previous MIP (2nd MIP), but finer horizontal grid resolution (1 km) than that of 2nd MIP (3 km) was used for understanding the behavior of atmospheric Cs in the vicinity of FDNPP. Results of the models elucidated that most of the observed high atmospheric Cs concentrations were well simulated, and the good performance of some models cancelled bad performance of some models when used as an ensemble, which highlights the advantage of multimodel ensemble. The analyses also indicated that the use of the finer grid resolution improved the meteorological field in the vicinity of FNDPP and the atmospheric Cs measured near FDNPP was more reasonably reproduced in 3rd MIP than 2nd MIP. As well as the evaluation of the performance of the model, we examined usefulness of the results of atmospheric dispersion simulation in an emergency. The analyses reported that the multimodel ensemble missed only 3% of the observed plumes, even if the absolute value of the simulated Cs in each model was different in the range of factor 3-6. The analyses also indicated that from six to eight models are required for making most of advantages of the multimodel ensemble.
Yamazawa, Hiromi*; Oura, Yasuji*; Moriguchi, Yuichi*; Terada, Hiroaki; Sekiyama, Tsuyoshi*; Goto, Daisuke*; Tsuruta, Haruo*; Sato, Yosuke*
no journal, ,
no abstracts in English
