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Titel |
Simulations of the transport and deposition of 137Cs over Europe after the Chernobyl Nuclear Power Plant accident: influence of varying emission-altitude and model horizontal and vertical resolution |
VerfasserIn |
N. Evangeliou, Y. Balkanski, A. Cozic, A. P. Møller |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
1680-7316
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Digitales Dokument |
URL |
Erschienen |
In: Atmospheric Chemistry and Physics ; 13, no. 14 ; Nr. 13, no. 14 (2013-07-29), S.7183-7198 |
Datensatznummer |
250018786
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Publikation (Nr.) |
copernicus.org/acp-13-7183-2013.pdf |
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Zusammenfassung |
The coupled model LMDZORINCA has been used to simulate the transport, wet
and dry deposition of the radioactive tracer 137Cs after accidental
releases. For that reason, two horizontal resolutions were deployed and used
in the model, a regular grid of 2.5° × 1.27°, and the same
grid stretched over Europe to reach a resolution of 0.66° × 0.51°. The vertical dimension is represented with two different
resolutions, 19 and 39 levels respectively, extending up to the mesopause. Four
different simulations are presented in this work; the first uses the regular
grid over 19 vertical levels assuming that the emissions took place at the
surface (RG19L(S)), the second also uses the regular grid over 19 vertical
levels but realistic source injection heights (RG19L); in the third
resolution the grid is regular and the vertical resolution 39 levels (RG39L)
and finally, it is extended to the stretched grid with 19 vertical levels
(Z19L). The model is validated with the Chernobyl accident which occurred in
Ukraine (ex-USSR) on 26 May 1986 using the emission inventory from
Brandt et al. (2002). This accident has been widely studied since 1986, and
a large database has been created containing measurements of atmospheric
activity concentration and total cumulative deposition for 137Cs from
most of the European countries.
According to the results, the performance of the model to predict the
transport and deposition of the radioactive tracer was efficient and
accurate presenting low biases in activity concentrations and deposition
inventories, despite the large uncertainties on the intensity of the source
released. The best agreement with observations was obtained using the
highest horizontal resolution of the model (Z19L run). The model managed to
predict the radioactive contamination in most of the European regions
(similar to De Cort et al., 1998), and also the arrival times of the
radioactive fallout. As regards to the vertical resolution, the largest
biases were obtained for the 39 layers run due to the increase of the levels
in conjunction with the uncertainty of the source term. Moreover, the
ecological half-life of 137Cs in the atmosphere after the accident
ranged between 6 and 9 days, which is in good accordance to what previously
reported and in the same range with the recent accident in Japan. The high
response of LMDZORINCA model for 137Cs reinforces the importance of
atmospheric modelling in emergency cases to gather information for protecting
the population from the adverse effects of radiation. |
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