Continuous Atmospheric Radon-222Concentration Observation in East Asia

摘要

Continuous observation of atmospheric radon-222 (~(222)Rn)concentration has beenoperated for years in China, Korea and Japan, including remote islands isolated in the ocean. Thesites were allocated along main wind directions of monsoon from the continent to the ocean inwinter and yellow dust storm in spring. Higher levels of ~(222)Rnconcentrations with typical diurnalvariation with early morning maxima were observed on the continent, while lower levels with nodiurnal variation at remote islands. Seasonal variations with summer minima and winter maximacommonly obtained, and they suggested contribution of ~(222)Rnoriginated from the continent toatmospheric ~(2220Rnover the remote islands. A backward trajectory analysis showed clearrelationship between variation in wind field and in ~(222)Rnconcentration at Hachijo Is., Japan, andproved availability of the observation for analysis of atmospheric transport in East Asia.