A model intercomparison of atmospheric 137Cs 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, Yousuke; Sekiyama, Tsuyoshi Thomas; Kajino, Mizuo; Quérel, Arnaud; Quélo, Denis; Kumakura, Hiroaki; Terada, Hiroaki; Kadowaki, Masanao; Takigawa, Masayuki; Morino, Yu; Uchida, Junya; Goto, Daisuke; Yamazawa, Hiromi

doi:10.1016/j.aeaoa.2020.100086

Cited by 17 publications

(9 citation statements)

References 65 publications

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“…The particulate fraction made up 72.6 % of the deposition of March 2011, which is presumed to be largely influenced by primary emissions. Here, it is interesting to note that most primary radio-Cs emissions are thought to be composed of water-soluble submicron aerosol particles (e.g., Kaneyasu et al, 2012 and almost all numerical simulations afterwards, such as Sato et al, 2020), while water-insoluble Cs-bearing microparticles (CsMP; Adachi et al, 2013, Igarashi et al, 2019b may contribute somewhat to primary emissions (Ikehara et al, 2020, Kajino et al, 2021. If the primary radio-Cs in aerosols were 100 % in water-soluble forms, the particulate fraction should have made up 0% of the precipitation in March 2011 (although, some of the water-soluble Cs could have converted to a water-insoluble form through adsorption to soil particles accumulated on the membrane filter during filtration).…”

Section: Deposition Amountsmentioning

confidence: 99%

Eight-year variations in atmospheric radiocesium in Fukushima City

Watanabe

Kajino

Ninomiya

et al. 2021

Preprint

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Abstract. After the Fukushima nuclear accident, atmospheric 134Cs and 137Cs measurements were taken in Fukushima city for eight years, from March 2011 to March 2019. The surface air concentrations and deposition of radio-Cs were high in winter and low in summer; these trends are the opposite of those observed in a contaminated forest area. The half-lives of 137Cs in the concentrations and deposition before 2015 (275 d and 1.11 y) were significantly shorter than those after 2015 (756 d and 4.69 y). The dissolved fractions of precipitation were larger than the particulate fractions before 2015, but the particulate fractions were larger after 2016. The half-lives of 137Cs in the concentrations and deposition were shorter before 2015, probably because the dissolved radio-Cs was discharged from the local terrestrial ecosystems more rapidly than the particulate radio-Cs. X-ray fluorescence analysis suggested that biotite may have played a key role in the environmental behavior of particulate forms of radio-Cs after 2014. However, the causal relationship between the seasonal variations in particle size distributions and the possible sources of particles is not yet fully understood. The current study also proposes a method of evaluating the consistency of a numerical model for radio-Cs resuspension and suggests that improvements to the model are necessary.

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Section: Deposition Amountsmentioning

confidence: 99%

Eight-year variations in atmospheric radiocesium in Fukushima City

Watanabe

Kajino

Ninomiya

et al. 2021

Preprint

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“…The numbers of points in the scatter diagrams were randomly reduced to 1/20 of their value to avoid too many overlaps of symbols. The two supersaturation levels of 0.1 % and 1 % were used for this evaluation as the typical ranges of stratiform and convective clouds (Seinfeld and Pandis, 2006).…”

Section: Aerosol-cloud Interactionsmentioning

confidence: 99%

“…The offline NHM-Chem with WRF was used for a multi-CTM intercomparison study in Asia (e.g., Li et al, 2019;Itahashi et al, 2020) and a multi-meteorological model study of the Fukushima nuclear accident (Kajino et al, 2019b). The offline model with SCALE was used for a multi-CTM intercomparison study for the Fukushima nuclear accident (Sato et al, 2020) and that with ASUCA is currently being used by JMA to conduct an operational forecast for photochemical smog bulletins (http://www.jma.go.jp/jma/kishou/know/ kurashi/smog.html, last access: 18 June 2020, in Japanese).…”

Section: Introductionmentioning

confidence: 99%

Comparison of three aerosol representations of NHM-Chem (v1.0) for the simulations of air quality and climate-relevant variables

et al. 2021

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Abstract. This study provides comparisons of aerosol representation methods incorporated into a regional-scale nonhydrostatic meteorology–chemistry model (NHM-Chem). Three options for aerosol representations are currently available: the five-category non-equilibrium (Aitken, soot-free accumulation, soot-containing accumulation, dust, and sea salt), three-category non-equilibrium (Aitken, accumulation, and coarse), and bulk equilibrium (submicron, dust, and sea salt) methods. The three-category method is widely used in three-dimensional air quality models. The five-category method, the standard method of NHM-Chem, is an extensional development of the three-category method and provides improved predictions of variables relating to aerosol–cloud–radiation interaction processes by implementing separate treatments of light absorber and ice nuclei particles, namely, soot and dust, from the accumulation- and coarse-mode categories (implementation of aerosol feedback processes to NHM-Chem is still ongoing, though). The bulk equilibrium method was developed for operational air quality forecasting with simple aerosol dynamics representations. The total CPU times of the five-category and three-category methods were 91 % and 44 % greater than that of the bulk method, respectively. The bulk equilibrium method was shown to be eligible for operational forecast purposes, namely, the surface mass concentrations of air pollutants such as O3, mineral dust, and PM2.5. The simulated surface concentrations and depositions of bulk chemical species of the three-category method were not significantly different from those of the five-category method. However, the internal mixture assumption of soot/soot-free and dust/sea salt particles in the three-category method resulted in significant differences in the size distribution and hygroscopicity of the particles. The unrealistic dust/sea salt complete mixture of the three-category method induced significant errors in the prediction of the mineral dust-containing cloud condensation nuclei (CCN), which alters heterogeneous ice nucleation in cold rain processes. The overestimation of soot hygroscopicity by the three-category method induced errors in the BC-containing CCN, BC deposition, and light-absorbing aerosol optical thickness (AAOT). Nevertheless, the difference in AAOT was less pronounced with the three-category method because the overestimation of the absorption enhancement was compensated by the overestimation of hygroscopic growth and the consequent loss due to in-cloud scavenging. In terms of total properties, such as aerosol optical thickness (AOT) and CCN, the results of the three-category method were acceptable.

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“…These studies indicate that the best model with respect to the depositions does not always perform the best with respect to the air concentrations. Two model-intercomparison studies were conducted using various ATDMs with a common source term and common meteorological fields to examine the influence of the parameterizations on the dispersion and deposition processes [18,19]. Sensitivity analyses were also performed for components contributing to the uncertainty in ATDM simulations (e.g.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of uncertainties derived from meteorological forecast inputs in plume directions predicted by atmospheric dispersion simulations

Yoshida

Nagai

Terada

et al. 2021

Journal of Nuclear Science and Technology

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Atmospheric transport, dispersion, and deposition models (ATDMs) can support decisionmaking during nuclear emergencies; however, uncertainties in the ATDM results need to be carefully evaluated. To investigate the uncertainties derived from meteorological forecast inputs, we conducted three-day forecast simulations every day for one year with hypothetical releases of radionuclides (one-hour releases every 6 h) from a nuclear facility. The forecast outputs were compared with the analysis outputs during the same period. The difference between the outputs is treated as the uncertainty in the forecasts and is represented as an angle based on the discrepancy in the plume directions between the analysis and forecast outputs. Using meteorological inputs made by Japan Meteorological Agency, the discrepancy angle (Ang) increased by approximately 10 � per day on an annual average basis. Meanwhile, the Ang values were occasionally 4-5 times higher than the annual average during short time periods. Since the Ang time series show seasonal and diurnal changes, the statistical characteristics likely depend on the geographical and meteorological conditions, as well as the types of meteorological inputs. Additionally, a main factor in the uncertainty is the wind-direction difference between the analysis and forecast outputs on scales of more than or less than 100 km.

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

Cited by 17 publications

References 65 publications

Eight-year variations in atmospheric radiocesium in Fukushima City

Eight-year variations in atmospheric radiocesium in Fukushima City

Comparison of three aerosol representations of NHM-Chem (v1.0) for the simulations of air quality and climate-relevant variables

Evaluation of uncertainties derived from meteorological forecast inputs in plume directions predicted by atmospheric dispersion simulations

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