Download This PaperChanges in Air Pollution, Land Surface Temperature, and Urban Heat Island During the COVID-19 Lockdown Over Chinese Three Urban Agglomerations
35 Pages Posted: 3 Jan 2023
Abstract
The urban lockdown caused by COVID-19 has affected the world economy and human activities, but it appears to have a positive impact on urban environment. In this study, MODIS land surface temperature (LST) and AOD data were selected, combined with Sentinel-5p images and meteorological elements, to analyze the changes and associations of air pollution, LST, and urban heat island (UHI) in three urban agglomerations over China during the COVID-19 lockdown. Results showed that: during the COVID-19 lockdown (February 2020), AOD and the concentration of atmospheric pollutants (PM2.5, NO2, and CO) have decreased significantly. LST in all three urban agglomerations increased by more than 1oC, which was mainly due to climate factors, but city lockdown will hinder the positive LST anomalies. The decrease of nighttime urban heat island intensity (UHIInight) in the three urban agglomerations was greater than daytime, and more than 25%. The reduction of UHIInight is mainly due to reduced human activities and air pollutant emissions. Although COVID-19 lockdown has a positive effect on air pollution and UHI, these changes quickly reverted when the lockdown policy is relaxed. Moreover, small-scale lockdowns do little to improve the environment. Our results have implications for assessing the environmental benefits of city lockdowns.
Keywords: COVID-19 lockdown, Air pollution, Land surface temperature, urban heat island, aerosol, Urban agglomeration
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