Short term variations of 7Be, 10Be concentrations in atmospheric boundary layer

Takeyasu Yamagata, Shinji Sugihara, Ichiro Morinaga, Hiroyuki Matsuzaki, Hisao Nagai

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Abstract

To compare meteorological conditions, short term variations of atmospheric concentrations of 7Be (T1/2 = 53.3 days) and 10Be (T1/2 = 1.5 × 106 years) were investigated at Tokyo and Fukuoka, Japan, and Pacific Ocean nearby Japan. Atmospheric concentrations of 7Be and 10Be at anticyclone condition were higher than that at cyclone condition to a factor of 2-10. Because of being influenced by re-suspended components from soil (10Be/7Be > 1000), temporal variability of 10Be/7Be was high in daytime and low in nighttime. But when corrected for re-suspended component using Al concentration as an indicator of soil the 10Be/7Be ratio was constant. Comparing 7Be and 10Be concentrations with 212Pb concentration as soil-generated component, we make a conclusion that high 7Be and 10Be concentration air mass is brought into boundary layer by high convection at daytime. Those diurnal variations were not observed in marine boundary layer. When cyclone passed through Fukuoka to Tokyo, which is 12 h behind, 7Be and 10Be concentrations also decreased with 12 h lag between Fukuoka and Tokyo. The 10Be/7Be ratio was constant during anticyclone to cyclone condition, and between Tokyo and Fukuoka. We conclude that after stratospheric aerosols enter into the upper troposphere they reside there for a certain period and mix uniformly in horizontal strata; later they are transported down to lower troposphere by anticyclone and penetrate into ground level air at daytime by convective strong mixing of boundary layer.

Original languageEnglish
Pages (from-to)1135-1138
Number of pages4
JournalNuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms
Volume268
Issue number7-8
DOIs
Publication statusPublished - Apr 1 2010

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All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Instrumentation

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