Nocturnal local winds carried radioactive material from Fukushima to Tokyo following the 2011 Fukushimia Daiichi nuclear accident.
AsianScientist (Jan. 17, 2017) – Nocturnal local winds were responsible for transporting radioactive material over 200km from the Fukushimia Daiichi nuclear accident to the Tokyo metropolitan area.
These findings by researchers from the University of Tokyo have been published in Scientific Reports. A research group led by Project Researcher Takao Yoshikane and Associate Professor Kei Yoshimura analyzed observational data and ran computer simulations to determine whether the radioactive plumes were carried by chance haphazard activity in the air or by a regular mechanism in the atmosphere. They found that the radioactive plume moves along two local wind systems that appear during the night on calm days when the impact of northwesterly seasonal winds and low-pressure systems are low. These nighttime local winds were formed by a difference in temperature between the North and the South, which created an upper layer of warm arm and a lower layer of cold air.
These findings indicate that should radioactive material be released over a long period of time, radioactive plumes could be frequently carried even to faraway places by such nocturnal local systems, and cause serious contamination in those areas.
On the other hand, the data show that it is possible to make a rough prediction of when, where, and how the radioactive plumes will travel by knowing the cycle of the winds. The current results could prove useful in determining when to seek shelter to avoid exposure to radiation.
“Stronger risk management strategies that allow for quick and cool-headed response to unforeseen situations are being sought,” said Yoshikane. “It is necessary to take into account local factors specific to each area, such as geographical features and traffic conditions.” “We hope that by expanding our study we can contribute to the development of risk management strategies through exchanges with people in other fields, government agencies, and local governments.”
The article can be found at: Yoshikane et al. (2016) Long-distance Transport of Radioactive Plume by Nocturnal Local Winds. ——— Source: University of Tokyo;