Spatial and Temporal Distributions of Atmospheric CO2 in East China Based on Data from Three Satellites

East China(23.6°–38.4°N,113.6°–122.9°E)is the largest developed region in China.Based on CO2 products retrieved from the Greenhouse Gases Observing Satellite(GOSAT),the spatial and temporal distributions of CO2 mixing ratios in East China during 2014–17 are discussed,and the retrieved CO2 from AIRS(Atmospheric Infrared Sounder)and OCO-2(Orbiting Carbon Observatory-2),as well as WLG(Waliguan)background station observations,are compared with those of GOSAT.The annual CO2 retrieved from GOSAT in East China ranged from 398.96±0.24 ppm in 2014 to 407.39±0.20 ppm in 2017,with a growth rate of 2.82±0.15 ppm yr^−1,which were higher than in other regions of China.The seasonal cycle presented a maximum in spring and a minimum in summer or autumn.Higher values were mainly concentrated in the coastal areas of Zhejiang Province,and lower values were concentrated in Jiangxi and the north of Fujian Province.CO2 observed in Fujian and parts of Jiangxi increased by less than 1.0 ppm during 2014–15,but enhanced significantly by more than 5.0 ppm during 2015–16,perhaps influenced by local emissions and global impacts.We calculated year-to-year CO2 enhancements in the Yangtze River Delta region during 2014–17 that were relatively low and stable,due to the region’s carbon emissions control and reduction policies.The annual and seasonal amplitudes of CO2 retrieved from AIRS were lower than those from GOSAT in East China,probably owing to the CO2 retrieved from AIRS better reflecting the characteristics of the mid-troposphere,while GOSAT is more representative of near-surface CO2.The spatial and temporal distribution characteristics of CO2 retrieved from OCO-2 were close to those from GOSAT in East China.

Variations in Column Concentration of Greenhouse Gases in China and Their Response to the 2015-2016 El Niño Event

Since the industrial revolution,enhancement of atmospheric greenhouse gas concentrations as a result of human activities has been the primary cause of global warming.The monitoring and evaluation of greenhouse gases are significant prerequisites for carbon emission control.Using monthly data of global atmospheric carbon dioxide(CO_(2))and methane(CH4)column concentrations(hereinafter XCO_(2)and XCH_(4),respectively)retrieved by the Greenhouse Gas Observation Satellite(GOSAT),we analyzed the variations in XCO_(2)and XCH_(4)in China during 2010-2022 after confirming the reliability of the data.Then,the influence of a strong El Niño event in 2015-2016 on XCO_(2)and XCH_(4)variations in China was further studied.The results show that the retrieved XCO_(2)and XCH_(4)from GOSAT have similar temporal variation trends and significant correlations with the ground observation and emission inventory data of an atmospheric background station,which could be used to assess the variations in XCO_(2)and XCH_(4)in China.XCO_(2)is high in spring and winter while XCH_(4)is high in autumn.Both XCO_(2)and XCH_(4)gradually declined from Southeast China to Northwest and Northeast China,with variation ranges of 401-406 and 1.81-1.88 ppmv,respectively;and the high value areas are located in the middle-lower Yangtze River basin.XCO_(2)and XCH_(4)in China increased as a whole during 2010-2022,with rapid enhancement and high levels of XCO_(2)and XCH_(4)in several areas.The significant increases in XCO_(2)and XCH_(4)over China in 2016 might be closely related to the strong El Niño-Southern Oscillation(ENSO)event during 2015-2016.Under a global warming background in 2015,XCO_(2)and XCH_(4)increased by 0.768%and 0.657%in 2016 in China.Data analysis reveals that both the XCO_(2)and XCH_(4)variations might reflect the significant impact of the ENSO event on glacier melting in the Tibetan Plateau.

Atmospheric sulfur hexafluoride in-situ measurements at the Shangdianzi regional background station in China

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 SF6 during the study period were 7.22 × 10-12（mol/mol, hereinafter） and 8.66 × 10-12, respectively. The averaged SF6 background 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）. SF6 background 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 SF6 background 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 SF6 mixing ratios occurred in autumn when local surface horizontal winds originated from W/WSW/SW/SWS/S sectors, while lower levels of SF6 mixing ratios appeared as winds originated from N/NNE/NE/ENE/E sectors.