A Comparative Analysis of Anthropogenic CO₂ Emissions at City Level Using OCO‐2 Observations: A Global Perspective

Abstract

Satellite observations of anthropogenic carbon dioxide (CO 2 ) emissions within urban settings offer unique potential to understand carbon sources and sinks and evaluate carbon mitigation strategies. Despite availability of column-averaged dry air mole fraction of CO 2 (X CO2 ) from Orbiting Carbon Observatory-2 (OCO-2), temporal variations of X CO2 and their drivers in cities remain poorly understood due to inconsistent definitions of urban extent, diverse urban forms, and unresolved impacts of urban vegetation on carbon fluxes. To this end, this study revealed that OCO-2 X CO2 measurements from 2014 to 2018 exhibited statistically significant seasonal and trend components for each city. A correlation analysis suggested a weak association between X CO2 trends and fossil fuel CO 2 emissions (FF CO2 ) trends but a close relationship between yearly average X CO2 and FF CO2 trends. Vegetation abundance exhibited a negative relationship with the X CO2 seasonality, though it only explained 21% of the variance. No statistically significant relationship between urban morphological factors (areal extent, complexity, and compactness) and temporal X CO2 components was observed. However, urban morphological factors had a close relationship with the total amount of FF CO2 aggregated over the study period. Thus, it was speculated that urban morphological factors exerted their influence on X CO2 through fossil fuel consumption. When only cities of high normalized difference vegetation index seasonality were used, statistically significant correlation coefficients between urban morphological factors and winter/summer averaged X CO2 measurements were found. The variations of these correlation coefficients between leaf-on and leaf-off seasons stress the important role that urban trees play in mitigating carbon emissions in cities. Key Points:• X CO 2 variation is associated with fossil fuel CO 2 emission, vegetation abundance, and urban form • Fossil fuel CO 2 emissions are highly related to urban morphological factors • Trees (or vegetation) play an important role in mitigating CO 2 emissions in cities Supporting Information:• Supporting Information S1

Neural-network-based estimation of regional-scale anthropogenic CO<sub>2</sub> emissions using an Orbiting Carbon Observatory-2 (OCO-2) dataset over East and West Asia

“…The two datasets showed a good correlation with a deter-mined coefficient (R 2 ) of 0.60. Several studies have correlated satellite-based XCO 2 anomalies with CO 2 emissions (Fu et al, 2019;Shekhar et al, 2020). Yang et al (2019) performed a correlation analysis between the GOSAT-based XCO 2 anomalies and the ODIAC CO 2 emissions over China and found a significant correlation with a determined coefficient (R 2 ) of 0.82 which increased up to 0.95 if the analysis was carried out with higher CO 2 emission values.…”

Progress and Perspective for In Situ Studies of CO2 Reduction

“…Currently, 85% of the energy in the world comes from fossil fuels such as coal, oil, and natural gas . It is worth noting that an excessive dependence on fossil fuels has led to an energy crisis, and at the same time, the released greenhouse gas CO 2 has caused serious environmental pollution problems. , Thus, how to effectively solve the issues of the energy crisis and environmental pollution has become a worldwide challenge. In this case, conversion of CO 2 to chemical fuels is considered to be one of the most efficient solutions. , However, since CO 2 molecules are exceptionally stable, the complicated conversion process and similar product potentials result in low catalytic efficiency and poor product selectivity .…”

Using OCO-2 Satellite Data for Investigating the Variability of Atmospheric CO2 Concentration in Relationship with Precipitation, Relative Humidity, and Vegetation over Oman

“…At the same time, precipitation, water vapor content [7], and consequently, vegetation cover have a direct effect [8] on the monthly CO 2 concentration fluctuations. example, Falahatkar et al investigated the interaction of land surface temperature and Normalized Difference Vegetation Index with GOSAT XCO 2 data for one year over Iran [27], while Fu et al tracked the fossil fuel consumption in urban areas and revealed the impacts of urban vegetation on seasonal variation of XCO 2 using OCO-2 observations [28]. In addition, Siabi et al assessed the CO 2 distribution over Iran using XCO 2 data from OCO2 during the growing season [29].…”