Changes of CH_4 Concentrations Obtained by Ground-based Observations at Five Atmospheric Background Stations in China
YANG Qian;GUAN Li;TAO Fa;LIANG Miao;SUN Wanqi;Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters,Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration;CMA Meteorological Observation Centre;
As the most important greenhouse gas next to carbon dioxide(CO_2), the enhancement of methane(CH_4) concentrations will accelerate the global warming. M-K mutation detection and other methods were used to analyze temporal, spatial variation and its formative of CH_4 concentrations in China's five major WMO/GAW background stations(Waliguan(WLG),Lin'an(LAN), Longfengshan(LFS), Shangdianzi(SDZ) and Shangri-La(XGLL)). The methane concentrations of WLG,LAN, LFS and SDZ sites are selected from January 2009 to December 2013, and the data of Shangri-La(XGLL) site is selected from July 2010 to December 2013. The results indicate that LAN station has the highest methane concentration, followed by LFS station, SDZ is in the middle, Shangri-La at least during the study period, with the mean value as 1 965×10~(-9),1 939×10~(-9), 1 914×10~(-9), 1 864×10~(-9) and 1 861×10~(-9) respectively. The average annual growth rate of methane concentration in WLG is 0.034%, the average annual growth rate in LAN, LFS, SDZ is 0.033%, 0.025%, 0.018% and 0.01%, respectively.LAN, LFS, SDZ have mutation point. The time of occurrence of the mutation point coincides with the time of the pollution process. The seasonal variations of each site are as follows: methane concentration at LAN background station reaches the valley in July; LFS presents "W" type; SDZ has the highest CH_4 concentration in July and August, WLG is similar to SDZ;XGLL site is affected by monsoon in summer, showing a distinct single peak. LAN, LFS, SDZ, XGLL stations show the same diurnal trend: the lowest value occurs in the afternoon, the concentration is higher in the night and early morning; there is a peak at midday at WLG station, which is due to grazing in pastoral areas.
【CateGory Index】： X51
【CateGory Index】： X51