Variations in Column Concentration of Greenhouse Gases in China and Their Response to the 2015-2016 El Nino 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 (CO2) and methane (CH4) column concentrations (hereinafter XCO2 and XCH4, respectively) retrieved by the Greenhouse Gas Observation Satellite (GOSAT), we analyzed the variations in XCO2 and XCH4 in China during 2010-2022 after confirming the reliability of the data. Then, the influence of a strong El Nino event in 2015-2016 on XCO2 and XCH4 variations in China was further studied. The results show that the retrieved XCO2 and XCH4 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 XCO2 and XCH4 in China. XCO2 is high in spring and winter while XCH4 is high in autumn. Both XCO2 and XCH4 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. XCO2 and XCH4 in China increased as a whole during 2010-2022, with rapid enhancement and high levels of XCO2 and XCH4 in several areas. The significant increases in XCO2 and XCH4 over China in 2016 might be closely related to the strong El Nino-Southern Oscillation (ENSO) event during 2015-2016. Under a global warming background in 2015, XCO2 and XCH4 increased by 0.768% and 0.657% in 2016 in China. Data analysis reveals that both the XCO2 and XCH4 variations might reflect the significant impact of the ENSO event on glacier melting in the Tibetan Plateau.