Mijani Naeim, Karimi Firozjaei Mohammad, Mijani Moein, Khodabakhshi Adeleh, Qureshi Salman, Jokar Arsanjani Jamal, Alavipanah Seyed Kazem
Department of Remote Sensing and GIS, Faculty of Geography, University of Tehran, Tehran, Iran.
Department of Geography and Urban planning, Faculty of Geography, Payame Noor University of Isfahan, Isfahan, Iran.
Adv Space Res. 2023 Jan 1;71(1):1017-1033. doi: 10.1016/j.asr.2022.09.052. Epub 2022 Sep 28.
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 temperature (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 estimated. Finally, the surface urban heat island intensity (SUHII) of different cities on the lockdown and pre-lockdown periods was compared with each other. The mean NLST of built-up lands in Milan (from 7.71 °C to 2.32 °C), Rome (from 5.05 °C to 3.54 °C) and Wuhan (from 3.57 °C to 1.77 °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 lockdown 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 °C, 1.78 °C, and 1.07 °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 anthropogenic activities) to creating cooler cities.
新冠疫情对我们的社会、环境和公众健康产生了重大影响，既有积极的一面，也有消极的一面。本研究的主要目的是监测新冠疫情封锁措施对城市降温的影响。为此，利用了意大利米兰和罗马以及中国武汉的陆地卫星8号卫星图像，观察封锁前和封锁期间的情况。首先，计算了新冠疫情封锁前和封锁期间的地表生物物理特征。然后，根据冷像元陆地表面温度（LST）对从陆地卫星热数据中反演得到的陆地表面温度进行归一化，并计算归一化陆地表面温度（NLST）的统计参数。此后，估算了NLST与基于指数的建成区指数（IBI）之间的相关系数（r）。最后，比较了不同城市在封锁期和封锁前期的地表城市热岛强度（SUHII）。与封锁前相比，米兰（从7.71℃降至2.32℃）、罗马（从5.05℃降至3.54℃）和武汉（从3.57℃降至1.77℃）建成区的平均NLST在封锁期间有所下降。米兰、罗马和武汉的NLST与IBI之间的r（绝对值）分别从封锁前的0.43、0.41和0.16降至封锁期间的0.25、0.24和0.12，这表明所有城市的降幅都很大。对这些城市的城市热岛效应分析表明，与封锁前相比，封锁期间的SUHII分别下降了0.89℃、1.78℃和1.07℃。结果表明，由于城市中巨大的人为压力大幅降低，人为活动和人为热通量（AHF）对城市热岛效应产生了高度且显著的影响。我们的结论提请人们关注新冠疫情封锁措施（减少人为活动）对打造更凉爽城市的贡献。
