Evidence That Reduced Air and Road Traffic Decreased Artificial Night-Time Skyglow during COVID-19 Lockdown in Berlin, Germany

Abstract

Artificial skyglow, the brightening of the night sky by artificial light at night that is scattered back to Earth within the atmosphere, is detrimental to astronomical observations and has an impact on ecosystems as a form of light pollution. In this work, we investigated the impact of the lockdown caused by the COVID-19 pandemic on the urban skyglow of Berlin, Germany. We compared night sky brightness and correlated color temperature (CCT) measurements obtained with all-sky cameras during the COVID-19 lockdown in March 2020 with data from March 2017. Under normal conditions, we expected an increase in night sky brightness (or skyglow, respectively) and CCT because of the transition to LED. This is supported by a measured CCT shift to slightly higher values and a time series analysis of night-time light satellite data showing an increase in artificial light emission in Berlin. However, contrary to this observation, we measured a decrease in artificial skyglow at zenith by 20% at the city center and by more than 50% at 58 km distance from the center during the lockdown. We assume that the main cause for the reduction of artificial skyglow originates from improved air quality due to less air and road traffic, which is supported by statistical data and satellite image analysis. To our knowledge, this is the first reported impact of COVID-19 on artificial skyglow and we conclude that air pollution should shift more into the focus of light pollution research.

An Analysis of the Work Resumption in China under the COVID-19 Epidemic Based on Night Time Lights Data

“…We also expect to use multispectral sensors covering the blue to the NIR range to study urban lighting more effectively in the future. Artificial night time skyglow as a supplement to night time light remote sensing data is affected by air quality [62,63]. Air pollution decreases due to COVID-19 city lockdown [64,65].…”

The ecology of COVID-19 and related environmental and sustainability issues

“…Derryberry et al ( 2020 ) observed that reduced noise pollution due to the lockdown immediately yielded benefits to wildlife (specifically birds). Reduced artificial light during the lockdowns (Jechow and Hölker 2020 ) may show similar benefits.…”

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

“…In the global fighting against the COVID-19 epidemic, NTL data has been used to assess its broad and profound impacts ( Small and Sousa, 2021 ). Generally, the decline in night lights after lockdown was observed worldwide ( Jechow and Hölker, 2020 ). Elvidge et al (2020) found that 82% of the population lived in administrative units where lighting dimmed because of the lockdown of cities in China.…”