Precise and continuous measurements of the atmospheric CH4 concentration were initiated at Syowa Station, Antarctica in February 1988, using a gas chromatograph equipped with a flame ionization detector. The measurement precision was typically ± 0.07% in a concentration range of 0.5 to 2.5 ppmv. The standard gases were CH4‐in‐air mixtures and their CH4 concentrations were determined gravimetrically with uncertainties of ± 0.2%. The CH4 concentrations measured at the station were extremely stable, and outliers due to local contamination such as station activities were not found. The diurnal CH4 variation was hardly observable throughout the year. The average seasonal CH4 variation showed minimum and maximum concentrations in early March and late September, respectively, and a peak‐to‐peak amplitude of 30 ppbv. Annual mean values of the CH4 concentration were 1640 and 1651 ppbv in 1988 and 1989, respectively. A concentration difference of 11 ppbv between the two years may suggest that recent annual increase rate of the CH4 concentration is smaller than previously reported values of about 1% year−1.
|Number of pages||9|
|Publication status||Published - 1992 Sep|
ASJC Scopus subject areas
- Atmospheric Science