Lockdown induced night-time light dynamics during the COVID-19 epidemic in global megacities

Abstract

The lockdown of cities to against the COVID-19 epidemic directly decreases urban socioeconomic activities. Remotely sensed night-time light (NTL) provides a macro perspective to capture these variations. Here, taking 20 global megacities as examples, we adopted the NASA’s Black Marble NTL data with a daily resolution to investigate their spatio-temporal changes. We collected daily NTL products for four weeks (one month) before and after the date of lockdown in each city, which were then summarized as weekly and monthly averaged NTL images after pre-processing (cloud removing, outlier detection, etc.). Results show that NTL overall decreased after the lockdown of cities, but with regional disparities and varying spatial patterns. Asian cities experienced the most obvious reduction of NTL. Particularly, the monthly averaged NTL in Mumbai, India, decreased by nearly 20% compared to one month before. However, there were no significant decline in NTL in European cities. African cities also experienced stable changes of NTL. Spatially, city centers darkened more obviously than the urban periphery. Facing emergencies, NTL data has broad applications in monitoring socioeconomic dynamics and assessing public policies in a near real-time manner.

An Impact Analysis of Artificial Light at Night (ALAN) on Bats. A Case Study of the Historic Monument and Natura 2000 Wisłoujście Fortress in Gdansk, Poland

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Sensing Global Changes in the Local Patterns of Energy Consumption in Cities During the Early Stages of the COVID-19 Pandemic

“…To understand changes in energy consumption in response to COVID-19 in each city, we analyse NTL satellite imagery, a well-established proxy for urban energy consumption 26 . In response to COVID-19, NTL imagery has been used to understand the initial impact on the US electricity sector 1 , changes in CO2 emissions nationally 9 , and changes in economic activity in the core of global megacities 27 .…”

“…Examination of the relationship between population density and NTL intensity (Figure 4) provides insight into the intra-urban distribution of energy consumption in response to COVID-19. Much attention has been paid to the risk of infection in dense urban centres 27,33 , particularly during the early stages of the outbreak. This is evident in cities in which NTL intensity declined 2/16 in densely populated areas (e.g.…”

Using Daily Nighttime Lights to Monitor Spatiotemporal Patterns of Human Lifestyle under COVID-19: The Case of Saudi Arabia

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