Kazuko Megumi

Factors, especially sunspot number, causing variations in surface air concentrations and depositions of 7Be in Osaka, Japan

We found that increasing sunspot number caused a significant negative effect on monthly and yearly average air concentration and yearly deposition of 7Be. For more than 15 years monthly average surface air concentration and monthly deposition of 7Be was measured in Osaka, Japan. The maximum monthly average surface air concentration of 7Be was 1.6 times higher than the minimum concentration through the fifteen year measurement span. Increase of several percent in the monthly averaged surface air concentration and monthly deposition of 7Be were observed in the monthly mean for February-March-April 1987 period following the 23 February supernova explosion in the Large Magellanic Cloud. The seasonal variation pattern which includes the lowest surface air concentration of 7Be in summer is due to the transport of air masses from low latitudes carrying low 7Be concentrations into the middle latitude region.