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Authors: Hendrik L. Tolman, Zulema Garaffo, Avichal Mehra, Ilya Riv MMAB
Title:Ocean Plume Modeling for the Fukushima Dai'ichi Event: Particle tracing
Additional Bibliographic Information:64 pp. + Appendices
MMAB Contribution Number:309
Keywords:RTOFS, HYCOM, Fukushima, particle tracing
Abstract:The National Centers of Environmental Prediction (NCEP) of the National Weather Service (NWS) used particle tracing to predict the movement of radionuclides in the ocean shortly after the Japanese Nuclear disaster near Fukushima. Daily nowcast/forecast fields from 1/12$\degree$ HYbrid Coordinate Ocean Model (HYCOM), implemented at NCEP as the Global Real Time Ocean Forecast System (RTOFS-Global), were used to track inert particles at the ocean surface, assuming that the surface behavior is reasonably representative for the ocean mixed layer, and that the radionuclides are mostly contained in and distributed by the upper mixed layer of the ocean. The focus was on producing actionable information for a governmental Inter-agency Working Group (IWG) in near real time using available resources. With the particle tracing information, NCEP produced estimates of retention time of radionuclides near the coast, as well as dispersion time scale of these materials through the Pacific Ocean, particularly by persistent current systems like the Kuroshio and its extension, and the Oyashio. This helped identify both potentially safe areas in the Pacific, and areas of potential exposure on the time scales of weeks to months. Using particle tracing combined with atmospheric deposits of radionuclides, a first guess of contamination of ocean surface water was produced. First particle tracing products were routinely delivered to the IWG within four weeks of the first significant release of radionuclide. The first quantitative offshore contamination estimates were made available to the IWG in approximately 6 weeks.

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Page last modified: Wednesday, 25-Sep-2013 17:12:39 UTC