Carbon Dioxide Variations of WMO/GAW Global Atmospheric Background Stations from 1971 to 2022
Ma Fang
Li Ying
Yang Guanying
Cai Haiyang
Song Xiaorui
Gu Taofeng
Pei Kunning
Long Guicai
Qin Zhengxin
Yan Peng
Abstract：The distribution of 32 global atmospheric background stations of WMO/GAW,the instru-ments and technical methods for on-line observation of CO2 mole fraction were investigated,and the char-acteristics of CO2 mole fraction observation data of 23 stations with more than 10 years were analyzed.The results are as follows.(1)From the distribution of stations,they are mainly distributed in Asia and Eu-rope,and most of them are near the sea.In terms of observation methods,China's global or regional background stations,like other global atmospheric background stations,all adopt observation techniques and methods that meet the requirements of WMO/GAW quality objectives.(2)The CO2 mole fraction of stations in the middle and high latitudes in the northern hemisphere fluctuates greatly.As far as the long-term trend is concerned,the CO2 mole fraction of stations in the southern and northern hemispheres shows an overall increasing trend,but the annual mean increment of CO2 mole fraction in the northern hemi-sphere is overall higher than that in the southern hemisphere.After removing the long-term trend,the seasonal maximum value of CO2 mole fraction in low latitudes in the northern hemisphere lags behind that in middle and high latitudes.The seasonal variation of CO2 mole fraction in middle and high latitudes in the southern hemisphere is opposite to that in low latitudes and northern latitudes,and the CO2 mole frac-tion in WLG is equivalent to that in middle and high latitudes in the northern hemisphere.(3)The aver-aged monthly amplitudes of stations above 2000 m and stations below 2000 m in recent five years are 18.1×10-6 mol/mol and 18.6×10-6 mol/mol,respectively,while those of ocean stations and land sta-tions are 12.5×10-6 mol/mol and 19.5×10-6 mol/mol,respectively.In comparison,stations above 2000 m and ocean stations exhibit smaller amplitudes.(4)The daily amplitude of seasonal CO2 mean mole fraction at high latitude representative stations in the southern and northern hemispheres is small,and the maximum is only 0.8×10-6 mol/mol,while that at middle latitude representative stations is 3.7×10-6 mol/mol,and that at low latitude representative stations is 1.5×10-6 mol/mol,and the maximum ampli-tude occurs in summer in the northern hemisphere.
Keywords：atmospheric background stationCO2 mole fractioncharacteristic analysis
Publication Date：2026-05-30
Online Publishing Date：2026-09-12(First online date of this platform, not the publication date of the document)
Pages：11( 55-65 )