Measurement of CF₂Cl₂ at Memanbetsu over the Period between October 1980 and March 1983

Abstract

   In order to obtain the atmospheric lifetime of CF₂Cl₂ (τ), the measurements of CF₂Cl₂ were performed from October 1980 to March 1983 at Memanbetsu, Hokkaido.
   The trend of monthly mean volume mixing ratios of CF₂Cl₂ when the wind directions were between NW and N was considered to represent the trend of the background mixing ratios. In this case, the mean increase rate from October 1980 to March 1983 was 1₅ ppt/year (ppt=10^-12).
   From the increase rate obtained in this study and the release rate reported by the Chemical Manufacturers Association (1983), τ was calculated to be 24 (5∼∞) years. Such a short lifetime seems to be due to the overestimation of the release rate in 1980 and 1981.