Exploring the effect of COVID-19 pandemic lockdowns on urban cooling: A tale of three cities

COVID-19 pandemic has had a major impact on our society, environment and public health, in both positive and negative ways. The main aim of this study is to monitor the effect of COVID-19 pandemic lockdowns on urban cooling. To do so, satellite images of Landsat 8 for Milan and Rome in Italy, and Wuhan in China were used to look at pre-lockdown and during the lockdown. First, the surface biophysical characteristics for the pre-lockdown and within-lockdown dates of COVID-19 were calculated. Then, the land surface tem-perature (LST) retrieved from Landsat thermal data was normalized based on cold pixels LST and statistical parameters of normalized LST (NLST) were calculated. Thereafter, the correlation coefficient (r) between the NLST and index-based built-up index (IBI) was esti-mated. Finally, the surface urban heat island intensity (SUHII) of different cities on the lockdown and pre-lockdown periods was com-pared with each other. The mean NLST of built-up lands in Milan (from 7.71 degrees C to 2.32 degrees C), Rome (from 5.05 degrees C to 3.54 degrees C) and Wuhan (from 3.57 degrees C to 1.77 degrees C) decreased during the lockdown dates compared to pre-lockdown dates. The r (absolute value) between NLST and IBI for Milan, Rome and Wuhan decreased from 0.43, 0.41 and 0.16 in the pre-lockdown dates to 0.25, 0.24, and 0.12 during lock -down dates respectively, which shows a large decrease for all cities. Analysis of SUHI for these cities showed that SUHII during the lockdown dates compared to pre-lockdown dates decreased by 0.89 degrees C, 1.78 degrees C, and 1.07 degrees C respectively. The results indicated a high and substantial impact of anthropogenic activities and anthropogenic heat flux (AHF) on the SUHI due to the substantial reduction of huge anthropogenic pressure in cities. Our conclusions draw attention to the contribution of COVID-19 lockdowns (reducing the anthro-pogenic activities) to creating cooler cities.(c) 2022 COSPAR. Published by Elsevier B.V. All rights reserved.

Automated summary

The COVID-19 pandemic has both positive and negative impacts on society, the environment, and public health. This study focuses on monitoring the effect of COVID-19 lockdowns on urban cooling. By analyzing satellite images of Milan, Rome, and Wuhan, it was found that the surface temperature in built-up areas decreased during the lockdown period, indicating a reduction in the urban heat island effect.