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.
Suggested CitationArticle: Rypina, Irina I., Jayne, Steven R., Yoshida, Sachiko, Macdonald, Alison M., Douglass, Elizabeth M., Buesseler, Ken O., "Short-term dispersal of Fukushima-derived radionuclides off Japan : modeling efforts and model-data intercomparison", Biogeosciences 10 (2013): 4973-4990, DOI:10.5194/bg-10-4973-2013, https://hdl.handle.net/1912/6205
The following license files are associated with this item:
Showing items related by title, author, creator and subject.
Inconsistent strategies to spin up models in CMIP5 : implications for ocean biogeochemical model performance assessment Seferian, Roland; Gehlen, Marion; Bopp, Laurent; Resplandy, Laure; Orr, James; Marti, Olivier; Dunne, John P.; Christian, James R.; Doney, Scott C.; Ilyina, Tatiana; Lindsay, Keith; Halloran, Paul R.; Heinze, Christoph; Segschneider, Joachim; Tjiputra, Jerry; Aumont, Olivier; Romanou, Anastasia (Copernicus Publications on behalf of the European Geosciences Union, 2016-05-12)During the fifth phase of the Coupled Model Intercomparison Project (CMIP5) substantial efforts were made to systematically assess the skill of Earth system models. One goal was to check how realistically representative ...
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 ...
Challenges associated with modeling low-oxygen waters in Chesapeake Bay : a multiple model comparison Irby, Isaac D.; Friedrichs, Marjorie A. M.; Friedrichs, Carl T.; Bever, Aaron J.; Hood, Raleigh R.; Lanerolle, Lyon W. J.; Li, Ming; Linker, Lewis; Scully, Malcolm E.; Sellner, Kevin G.; Shen, Jian; Testa, Jeremy M.; Wang, Hao; Wang, Ping; Xia, Meng (Copernicus Publications on behalf of the European Geosciences Union, 2016-04-06)As three-dimensional (3-D) aquatic ecosystem models are used more frequently for operational water quality forecasts and ecological management decisions, it is important to understand the relative strengths and limitations ...