Characteristics of Atmospheric Methane Concentration Variation At Mt. Waliguan

By using gas chromatographic method, in-situ atmospheric CH4 was measured continuously at China Global Atmosphere Watch Baseline Observatory at Mt. Waliguan. Combining with FLASK CH4 data obtained from NOAA/CMDL, the variation features of atmospheric background CH4 concentration in the inland plateau of China are presented. The results show that the CH4 concentration at Mt. Waliguan are in the range of 1780×10－ 9 ~ 1840×10－ 9, it is in accord with the CH4 distribution in the area of mid and high latitudes. CH4 concentration at Mt. Waliguan has evident diurnal fluctuation, its pattern and amplitude in summer are different from those in winter and spring; there appears no obvious seasonal variation, and it is dissimilar to the feature of seasonal variation and to the geographical distribution of variation amplitude for global atmospheric CH4 background concentration. The results also show that there are distinct interannual variations. CH4 mean annual concentration increases with years and the variations of annual growing rate correspond with the trend of mean variation for atmospheric CH4 in the Northern Hemisphere.