Monitoring of Carbon Monoxide (CO) changes in the atmosphere and urban environmental indices extracted from remote sensing images for 932 Iran cities from 2019 to 2021

Carbon Monoxide (CO) is an important urban pollutant with a relation to transition economies based on emission intensities. In this study, Sentinel-5, MODerate resolution Imaging Spectroradiometer (MODIS), and Landsat-8 images were used to investigate the variations of CO and urban environmental indices and the correlations between them. From the assessed correlations for 932 Iranian cities, it occurred that the assessed indices were all correlated. The highest CO levels were 0.031 in the spring of 2019 and 2020, whereas in 2021 it was equal to 0.030 in both the spring and winter, respectively. In 2019 and 2020 the maximum values of the Enhanced Vegetation Index (EVI) in the spring were 0.181 and 0.183. Exceptionally high Absorbing Aerosol Index (AAI) values of - 0.834 and - 1.0, along with Urban Index (UI) of 0.102 and 0.092, were correlated with recorded spikes in CO level, despite that these seasons' EVI values were not so abnormal. It was forecasted that in 2030 rises in the CO level by 13.2% in the winter and by 17.5% in the fall are expected, with the simultaneous increase of AAI by 204.5% and 980.2%, and Aerosol Optical Depth (AOD) by 27% and 5% in the winter and spring, respectively.

Automated summary

This study examined the variations of carbon monoxide (CO) and urban environmental indices and their correlations using Sentinel-5, MODerate resolution Imaging Spectroradiometer (MODIS), and Landsat-8 images. Correlations were found among the assessed indices for 932 Iranian cities. The highest CO levels occurred in the spring of 2019 and 2020, with a slight decrease in 2021. The Enhanced Vegetation Index (EVI) showed relatively high values in the spring of 2019 and 2020. Abnormally high values of the Absorbing Aerosol Index (AAI) and Urban Index (UI) were correlated with spikes in CO level.