We present in-situ measurements of atmospheric sulfur hexafluoride(SF6)conducted by an automated gas chromatograph–electron capture detector system and a gas chromatography/mass spectrometry system at a regional background site,Shangdianzi,in China,from June 2009 to May 2011,using the System for Observation of Greenhouse gases in Europe and Asia and Advanced Global Atmospheric Gases Experiment(AGAGE)techniques.The mean background and polluted mixing ratios for SF6during the study period were 7.22×10-12(mol/mol,hereinafter)and 8.66×10-12,respectively.The averaged SF6background mixing ratios at Shangdianzi were consistent with those obtained at other AGAGE stations located at similar latitudes(Trinidad Head and Mace Head),but larger than AGAGE stations in the Southern Hemisphere(Cape Grim and Cape Matatula).SF6background mixing ratios increased rapidly during our study period,with a positive growth rate at 0.30×10-12year-1.The peak to peak amplitude of the seasonal cycle for SF6background conditions was 0.07×10-12,while the seasonal fluctuation of polluted conditions was 2.16×10-12.During the study period,peak values of SF6mixing ratios occurred in autumn when local surface horizontal winds originated from W/WSW/SW/SWS/S sectors,while lower levels of SF6mixing ratios appeared as winds originated from N/NNE/NE/ENE/E sectors.
Bo YaoLingxi ZhouLingjun XiaGen ZhangLifeng GuoZhao LiuShuangxi Fang
We carried out a downscaling treatment over China using the CarbonTracker numerical model,which was applied using double grid nesting technology(3°×2°over the whole globe,1°×1°over China),simulating and analyzing atmospheric CO2concentrations over 10 recent years(2000–2009).The simulation results agreed very well with observed data from four background atmospheric monitoring stations in China(The periods for which the simulation results and observed values be compared were January2000 to December 2009 for the WLG station and June 2006 to December 2009 for the SDZ,LFS,and LAN stations),giving correlation coefficients of>0.7.The high-resolution simulation data correlated slightly better than the low resolution simulation data with the observed data for three of the regions’atmospheric background stations.Further analysis of the annual,seasonal CO2concentration variations at the background stations showed that the CO2concentration increased each year over the study period,with an average annual increase of more than 5%,and annual increases of more than 7%at the Shangdianzi and Lin’an stations.Seasonal CO2variations were greater at the Longfengshan station than at the Shangdianzi or Lin’an stations.However,the CO2concentrations were higher at the Shangdianzi and Lin’an stations because they are greatly affected by human activities in the Jingjinji and Changjiang Delta economic zones.Spatial distribution in CO2concentrations and fluxes were higher in eastern than in western China.
CHENG YanLiAN XingQinYUN FangHuaZHOU LingXiLIU LiXinFANG ShuangXiXU Lin
