Short-term dispersal of Fukushima-derived radionuclides off Japan : modeling efforts and model-data intercomparison
Rypina, Irina I.
Jayne, Steven R.
Macdonald, Alison M.
Douglass, Elizabeth M.
Buesseler, Ken O.
MetadataShow full item record
The Great East Japan Earthquake and tsunami that caused a loss of power at the Fukushima nuclear power plants (FNPP) resulted in emission of radioactive isotopes into the atmosphere and the ocean. In June of 2011, an international survey measuring a variety of radionuclide isotopes, including 137Cs, was conducted in surface and subsurface waters off Japan. This paper presents the results of numerical simulations specifically aimed at interpreting these observations and investigating the spread of Fukushima-derived radionuclides off the coast of Japan and into the greater Pacific Ocean. Together, the simulations and observations allow us to study the dominant mechanisms governing this process, and to estimate the total amount of radionuclides in discharged coolant waters and atmospheric airborne radionuclide fallout. The numerical simulations are based on two different ocean circulation models, one inferred from AVISO altimetry and NCEP/NCAR reanalysis wind stress, and the second generated numerically by the NCOM model. Our simulations determine that > 95% of 137Cs remaining in the water within ~600 km of Fukushima, Japan in mid-June 2011 was due to the direct oceanic discharge. The estimated strength of the oceanic source is 16.2 ± 1.6 PBq, based on minimizing the model-data mismatch. We cannot make an accurate estimate for the atmospheric source strength since most of the fallout cesium had left the survey area by mid-June. The model explained several key features of the observed 137Cs distribution. First, the absence of 137Cs at the southernmost stations is attributed to the Kuroshio Current acting as a transport barrier against the southward progression of 137Cs. Second, the largest 137Cs concentrations were associated with a semi-permanent eddy that entrained 137Cs-rich waters, collecting and stirring them around the eddy perimeter. Finally, the intermediate 137Cs concentrations at the westernmost stations are attributed to younger, and therefore less Cs-rich, coolant waters that continued to leak from the reactor in June of that year.
© The Author(s), 2013. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Biogeosciences 10 (2013): 4973-4990, doi:10.5194/bg-10-4973-2013.
The following license files are associated with this item:
Showing items related by title, author, creator and subject.
Historical and idealized climate model experiments : an intercomparison of Earth system models of intermediate complexity Eby, Michael; Weaver, Andrew J.; Alexander, K.; Zickfeld, K.; Abe-Ouchi, A.; Cimatoribus, A. A.; Crespin, E.; Drijfhout, S. S.; Edwards, N. R.; Eliseev, A. V.; Feulner, G.; Fichefet, T.; Forest, C. E.; Goosse, H.; Holden, P. B.; Joos, Fortunat; Kawamiya, M.; Kicklighter, David W.; Kienert, H.; Matsumoto, K.; Mokhov, I. I.; Monier, Erwan; Olsen, S. M.; Pedersen, J. O. P.; Perrette, M.; Philippon-Berthier, G.; Ridgwell, Andy; Schlosser, A.; Schneider von Deimling, T.; Shaffer, G.; Smith, R. S.; Spahni, R.; Sokolov, Andrei P.; Steinacher, M.; Tachiiri, K.; Tokos, K.; Yoshimori, M.; Zeng, Ning; Zhao, F. (Copernicus Publications on behalf of the European Geosciences Union, 2013-05-16)Both historical and idealized climate model experiments are performed with a variety of Earth system models of intermediate complexity (EMICs) as part of a community contribution to the Intergovernmental Panel on Climate ...
Incorporating ‘recruitment’ in matrix projection models : estimation, parameters, and the influence of model structure Cooch, Evan G.; Cam, Emmanuelle; Caswell, Hal (2010-07)Advances in the estimation of population parameters using encounter data from marked individuals have made it possible to include estimates of the probability of recruitment in population projection models. However, ...
Zhang, Huai-Min (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1995-02)Inverse modeling activities in oceanography have recently been intensified, aided by the oncoming observational data stream of WOCE and the advance of computer power. However, interpretations of inverse model results ...