大気メタン濃度の測定について

Abstract

We have measured atmospheric methane with gas chromatography since Novem-ber 1987. In this paper we estimate the error of measurements to be 0.016 ppmv, andconclude that it is precise enough to detect the seasonal cycles and the interannualtrends. The mixing ratio, whose average for December 1987-March 1988 is 1.791ppmv, is in good agreement with that measured at Meteorological Research Institutein Tsukuba. The monthly mean mixing ratio has been decreasing to the sameextent at both stations since December 1987. We also made hourly observations on27 and 28 February 1988, and found that the diurnal variation is comparable to theseasonal variation in magnitude.