At the time of the 2011 TEPCO Fukushima Daiichi Nuclear Power Station accident, the local wind blowing at night was deeply involved in the background of radioactive materials being transported from Fukushima to the Tokyo metropolitan area. It was clarified by the observation data analysis and computer simulation of the specially appointed lecturer Takao Yoshikane and Associate Professor Kei Yoshimura.
According to the University of Tokyo, radioactive materials released from the nuclear power plant were confirmed multiple times in the Tokyo metropolitan area about 200 km away during the Fukushima nuclear accident, but the mechanism in the atmosphere was not well understood.
When the research group analyzed the observation data and conducted a computer simulation, the strong monsoon from the northwest direction by the Siberian cold air group and the local wind that blows on the night of the day when the influence of the low pressure is small are related. It turned out.
This local wind is the northerly wind that blows from off Fukushima to the offshore of Kanto, and the northeastern local wind that develops at night near Kanto.It was also found that the local wind is created by the light warm air generated by the temperature difference between north and south toward the upper layer and the heavy cold air toward the lower layer.
When radioactive material is carried in a local wind, if the release is long-term, the radioactive material is frequently carried to remote areas, and there is a risk of causing high-concentration pollution.On the other hand, it is possible to roughly predict where and how much radioactive material will be carried from the periodicity of the local wind.The research group believes that this finding will be useful for future exposure measures.
