Correlation Analysis Of Satellites Derived Atmospheric CO₂ Variations And Anthropogenic Emissions

Anthropogenic CO2 emissions are the dominant factor driving atmospheric CO2 concentration enhancement.However,the magnitude of the increase of CO2 concentration due to regional anthropogenic emissions remains unclear.Satellite-derived observations of atmospheric CO2 concentration provide a promising and effective means by which to monitor and evaluate regional anthropogenic CO2 emissions.The study used the column-averaged dry air mole fraction of CO2(XCO2)derived from the observations of the Greenhouse gases Observation SATellite(GOSAT)and Orbiting Carbon Observatory-2(OCO-2),combined with the simulation of atmospheric transport trajectory,to assess quantitatively the effect of high-density anthropogenic emissions on atmospheric CO2 enhancement.The study collected original XCO2 data(v02.xx)from a five-year period(January 2010 to October 2015),released by the GOSAT project of the National Institute for Environmental Studies in Japan.Also we collected XCO2 data(r7 Lite)from a two-year period(September 2014 to December 2016)released by National Aeronautics and Space Administration.Two high-density urban areas located within the same latitudinal zone(35–50°N)were selected as anthropogenic emission regions(emission-regions).These areas comprised the Beijing–Tianjin–Hebei area centered on Beijing(43 million square kilometers)in northern China and the urban agglomeration that includes New York City(55 million square kilometers)in the eastern America,for which the magnitudes of anthropogenic CO2 emissions were about 950 and 1312 Tg CO2/yr,respectively,according to the CO2 emission inventory in 2010 released by the Carbon Dioxide Information Analysis Center(CDIAC).Another two regions with lower emissions,considered as background-regions for comparison with the emission-regions,were prepared according to the distribution of potential temperature and CO2 emission data from CDIAC,where anthropogenic CO2 emissions in 2010 were about 127 and 123 Tg CO2/yr,respectively.XCO2 enhancements were calaculated by subtracting retrieved background values from those retrieved over urban areas.The yearly averaged XCO2 data were calculated based on the seasonally averaged XCO2 data using the original GOSAT and OCO-2 XCO2 retrievals from the four regions.In comparison with the background-regions,the results showed the enhancements of CO2 concentration observed by GOSAT in the emission-regions were,on average,1.8 and 2.0 ppm in the Beijing–Tianjin–Hebei area and urban agglomeration in the America,respectively.Similaryly,The enhancements detected by OCO-2 were 2.3 and 1.2 ppm.Moreover,the enhancements were highest in winter(2.4 ± 0.6 and 2.8 ± 0.8 ppm detected by GOSAT in China and America,respectively;2.1 ± 0.1 and 2.3 ± 0.1 ppm detected by GOSAT in China and America,respectively).Intriguingly,analysis of the monthly variations from GOSAT revealed that CO2 concentration in the Beijing–Tianjin–Hebei area decreased anomalously by 3.2 ppm during the Asia-Pacific Economic Cooperation(APEC)summit in November 2014 compared with the period before the summit.This anomalous drop probably reflects the effects of the artificial control of CO2 emissions implemented by the government during the APEC summit in order to improve air quality.Considering the the different satellite parameters of GOSAT and OCO-2,XCO2 in each regions and XCO2 enhancements between emission-region and background-region during the overlapping period from September 2014 to July 2015 were collected.The result show that XCO2 obseved by OCO-2 is slightly higher than those by GOSAT,but the enhancements denoted as 2.0 ppm both by GOSAT and OCO-2.Affected by our method which calclute the mean value of each region and the difference in observation number,spatial resolution and sensor,random fluctuations in enhancements can be deteced,and the enhancements dected by GOSAT sometimes slightly higher than OCO-2.Furthermore,we analyzed the regional atmospheric transport trajectory simulated by the HYSPLIT model.Slightly affected by the emission sources from upwind regions,especially in America,the XCO2 in background-region can not characterize reasonably the mean state of the background atmosphere.This may lead to a smaller enhancements of CO2 concentration observed by satellite between emission-region and background-region than the actual value.The study results demonstrate the efficacy of using satellite-derived observations for evaluating the impact of anthropogenic emissions on the enhancement of atmospheric CO2 by analyzing changes in regional CO2 concentration.This provides a promising method with which to verify regional anthropogenic emissions and to support governmental oversight,control,and decision making regarding CO2 emission reduction.