TY - JOUR
T1 - Concentrations of 222RN, its short-lived daughters and 212PB and their ratios under complex atmospheric conditions and topography
AU - Kataoka, Toshio
AU - Yunoki, Eiji
AU - Shimizu, Mitsuo
AU - Mori, Tadashige
AU - Tsukamoto, Osamu
AU - Takahashi, Satoshi
AU - Fudeyasu, Hironori
AU - Ohashi, Yukitaka
AU - Sahashi, Ken
AU - Maitani, Toshihiko
AU - Miyashita, Koh'ichi
AU - Iwata, Toru
AU - Sasaki, Takayuki
AU - Fujikawa, Yoko
AU - Kudo, Akira
AU - Shaw, Roger H.
N1 - Funding Information:
This work was funded by the Japanese Ministry of Education, Culture, Sports, Science and Technology. The authors wish to thank Mr. Akinori Matano regarding negotiations with the Ministry to acquire funding for this work.
PY - 2003/4
Y1 - 2003/4
N2 - Atmospheric activity concentrations of 212Pb and short-lived 222Rn daughters, together with meteorological elements, have been observed continuously at three sites at Kamisaibara Village in Japan. In addition, atmospheric activity concentration of 222Rn, equilibrium-equivalent concentration of 222Rn and conditions of the lower atmosphere were observed for three intensive observation periods at Akawase, one of the three sites in Kamisaibara Village. The equilibrium-equivalent concentration of 222Rn is almost the same as the atmospheric activity concentration of short-lived 222Rn daughters. The activity concentrations of 212Pb and the short-lived 222Rn daughters and their ratio were low in the daytime owing to convective mixing, and high at night owing to the surface-based inversion during periods of no precipitation. Their variations have several patterns corresponding to the scale of the drainage wind or weak mixing. Mechanical mixing due to strong winds through both day and night during the first and second observation periods made the atmospheric activity concentrations of 212Pb and the short-lived 222Rn daughters continuously low. However, their ratios were continuously high during the first period yet continuously low during the second period. This difference can be explained by the effect of extraction of 220Rn and 222Rn due to strong winds and snow cover. There were also cases in which the ratio of the atmospheric activity concentration of 212Pb to that of the short-lived 222Rn daughters at night was equal to or less than the ratio in the daytime. This inverse trend, as in the period of no precipitation mentioned above, is considered to be due to near-neutral conditions on these nights. We find a difference in the ratio of the equilibrium-equivalent concentration of 222Rn (the activity concentration of short-lived 222Rn daughters) to the activity concentration of 222Rn during the first observation period and that during the second. The difference can be explained by snow cover on the ground. We also find differences among the ratios of the activity concentration of the short-lived 222Rn daughters to that of 222Rn during the three observation periods. These differences can be explained by the submergence of paddy fields.
AB - Atmospheric activity concentrations of 212Pb and short-lived 222Rn daughters, together with meteorological elements, have been observed continuously at three sites at Kamisaibara Village in Japan. In addition, atmospheric activity concentration of 222Rn, equilibrium-equivalent concentration of 222Rn and conditions of the lower atmosphere were observed for three intensive observation periods at Akawase, one of the three sites in Kamisaibara Village. The equilibrium-equivalent concentration of 222Rn is almost the same as the atmospheric activity concentration of short-lived 222Rn daughters. The activity concentrations of 212Pb and the short-lived 222Rn daughters and their ratio were low in the daytime owing to convective mixing, and high at night owing to the surface-based inversion during periods of no precipitation. Their variations have several patterns corresponding to the scale of the drainage wind or weak mixing. Mechanical mixing due to strong winds through both day and night during the first and second observation periods made the atmospheric activity concentrations of 212Pb and the short-lived 222Rn daughters continuously low. However, their ratios were continuously high during the first period yet continuously low during the second period. This difference can be explained by the effect of extraction of 220Rn and 222Rn due to strong winds and snow cover. There were also cases in which the ratio of the atmospheric activity concentration of 212Pb to that of the short-lived 222Rn daughters at night was equal to or less than the ratio in the daytime. This inverse trend, as in the period of no precipitation mentioned above, is considered to be due to near-neutral conditions on these nights. We find a difference in the ratio of the equilibrium-equivalent concentration of 222Rn (the activity concentration of short-lived 222Rn daughters) to the activity concentration of 222Rn during the first observation period and that during the second. The difference can be explained by snow cover on the ground. We also find differences among the ratios of the activity concentration of the short-lived 222Rn daughters to that of 222Rn during the three observation periods. These differences can be explained by the submergence of paddy fields.
KW - Concentration of Pb
KW - Concentration of Rn
KW - Concentration of short-lived Rn daughters
KW - Snow depth
KW - Submergence of paddy fields
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U2 - 10.1023/A:1021540506779
DO - 10.1023/A:1021540506779
M3 - Article
AN - SCOPUS:0037399331
VL - 107
SP - 219
EP - 249
JO - Boundary-Layer Meteorology
JF - Boundary-Layer Meteorology
SN - 0006-8314
IS - 1
ER -