The 2020 data are clearly an outlier: in 2020, the mean background component for all analysed areas (without China) was - 6.0 % ± 1.2 % and the mean urban component was - 26.7 ± 2.6 % or 20 σ below the baseline level from the other years. Suggesting that there were no substantial drifts or shifts in TROPOMI data. Urban components were remarkably stable in 2018, 2019, and 2021, withĪverages of all analysed areas all being within ☒.5 % and No correlation was found between changes in background That changes in traffic were one of the key elements in the decline in urban In Google mobility data (the correlation coefficient is 0.62) confirming Estimated changes in urban emissions are correlated with changes Industrial sources in the analysed urban areas varied greatly from region to region from - 4.8 ± 6 % for China to - 40 ± 10 %įor India. Period, was, on average, only - 4.4 ± 8 %. Urban areas in China, where the lockdown was over during the analysed India, South America, andĪ part of Europe (particularly, Italy, France, and Spain) demonstrated a While the background NO 2 component remained almost unchanged, the urban NO 2 componentĭeclined by −18 % to −28 % over most regions. (VCD) values measured by the Tropospheric Monitoring Instrument (TROPOMI) on board the Sentinel-5 Precursor over 261 urban areas for the period from 16 March to 15 June 2020 were compared with the average VCD values for the same period in 20. The tropospheric NO 2 vertical column density Surface elevation data as well as coordinates of industrial sources were Satellite data by a statistical model with empirical plume dispersionįunctions driven by a meteorological reanalysis. Of the COVID-19 lockdown on each of them. Sources, and NO 2 from industrial point sources) is applied to estimate the impact Isolation of three components (background NO 2, NO 2 from urban Well-established, understanding the details remains a challenge since While the overall NO 2 decline over some large cities is The COVID-19 lockdown had a large impact on anthropogenic emissions of air pollutants and particularly on nitrogen dioxide (NO 2).
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