Decoding spatiotemporal dynamics in atmospheric CO2 in Chinese cities: Insights from satellite remote sensing and geographically and temporally weighted regression analysis

Understanding the primary factors influencing atmospheric carbon dioxide (CO2) dynamics is essential for addressing global climate change. However, these factors' spatial and temporal impact is seldom considered in the extant literature. This study employs a geographically and temporally weighted regression (GTWR) to examine the magnitude and direction of the effects that human activities, ecological conditions, and meteorological parameters exert on atmospheric CO2 variations. This examination encompasses 356 Chinese cities, utilizing satellite-derived column-averaged dry air mole fraction of carbon dioxide (XCO2) data from 2010 to 2019. Our findings reveal that cities in eastern China predominantly exhibit higher atmospheric CO2 concentrations, with most average values exceeding 399.34 ppm. Conversely, western regions generally maintain levels below 398.98 ppm. Trend analyses show a consistent increase over the decade, with a rate of 2.25-2.54 ppm/yr, coupled with pronounced seasonal variations. Anthropogenic emissions are found to amplify atmospheric CO2 concentrations during springs (overall-averaged GTWR coefficient of 0.72 ppm), autumns (0.51 ppm), and winters (0.87 ppm), especially in western cities. Vegetative activities can effectively reduce atmospheric CO2 during summers nationwide (temporally-averaged GTWR coefficients of -5.67 ~ -0.41 ppm) and autumn in southern cities (-1.32-0.00 ppm). From a meteorological perspective, increased summer relative humidity (overall-averaged coefficient of 2.41 ppm) and precipitation (1.57 ppm) can intensify atmospheric CO2 in most Chinese Cities. At the same time, warmer winter temperatures (-0.63 ppm) can mitigate it. Wind speed generally reduces atmospheric CO2 levels during spring (-1.02 ppm), autumn (-1.55 ppm), and winter (-1.76 ppm). Yet, it can heighten atmospheric CO2 concentrations during summers, particularly in eastern cities (0.07 ppm). The relationships between atmospheric CO2 concentrations and their influencing factors present significant spatial and seasonal variations. These findings offer comprehensive guidance for regions in developing targeted carbon emission control policies and enable a more practical approach to sustainable development.