Recovering the city street lighting fraction from skyglow measurements in a large-scale municipal dimming experiment

Barentine, John C.; Kundracík, František; Kocifaj, Miroslav; Sanders, Jessie C.; Esquerdo, Gilbert A.; Dalton, Adam M.; Foott, Bettymaya; Grauer, A. D.; Tucker, Scott; Kyba, Christopher C. M.

doi:10.1016/j.jqsrt.2020.107120

Cited by 23 publications

(25 citation statements)

References 27 publications

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“…While this experiment was taking place, we also conducted measurements of sky brightness. 52 These experiments showed that there is a consistent and substantial change in lighting at midnight, which we attribute to private lighting on timers (skyglow reduced by an estimated 2.5% due to changes in non-City of Tucson lights at midnight). Since there is not a straightforward relationship between skyglow and DNB radiance, here, we report only results for the period during which DNB flies over (around 2:20 local time).…”

Section: Stability Of Non-city Lights and Blue Light Emissionsmentioning

confidence: 66%

“…In our study of the skyglow over Tucson that was conducted together with this experiment, radiative transfer modeling suggested that street lighting was responsible for 14% of the skyglow over the city, which is similar to the result presented here for DNB radiance. 52 However, a more direct calculation based simply on the change of sky brightness at midnight in the same paper suggested street lighting is only responsible for 2-3% of the skyglow directly over the measurement locations. Our spatial results show that the fraction of light emissions due to street lights vary throughout the city (Figure 12), and it should therefore be expected that the relative contribution of streetlights to skyglow also displays spatial variations.…”

Section: Discussionmentioning

confidence: 95%

“…All of these fractions are presumably smaller in the early evening, when more private lighting is active. 52 Determining this value for before midnight cannot be achieved without a night lights observing satellite with an earlier overpass time.…”

Section: Percentage Of Streetlight Emissionsmentioning

confidence: 99%

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Direct measurement of the contribution of street lighting to satellite observations of nighttime light emissions from urban areas

Kyba

Ruby

Kuechly

et al. 2020

Lighting Research & Technology

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Nighttime light emissions are increasing in most countries worldwide, but which types of lighting are responsible for the increase remains unknown. Also unknown is what fraction of outdoor light emissions and associated energy use are due to public light sources (i.e. streetlights) or various types of private light sources (e.g. advertising). Here we show that it is possible to measure the contribution of street lighting to nighttime satellite imagery using ‘smart city’ lighting infrastructure. The city of Tucson, USA, intentionally altered its streetlight output over 10 days, and we examined the change in emissions observed by satellite. We find that streetlights operated by the city are responsible for only 13% of the total radiance (in the 500–900 nm band) observed from Tucson from space after midnight (95% confidence interval 10–16%). If Tucson did not dim their streetlights after midnight, the contribution would be 18% (95% confidence interval 15–23%). When streetlights operated by other actors are included, the best estimates rise to 16% and 21%, respectively. Existing energy and lighting policy related to the sustainability of outdoor light use has mainly focused on street lighting. These results suggest an urgent need for consideration of other types of light sources in outdoor lighting policy.

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Section: Stability Of Non-city Lights and Blue Light Emissionsmentioning

confidence: 66%

Section: Discussionmentioning

confidence: 95%

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Direct measurement of the contribution of street lighting to satellite observations of nighttime light emissions from urban areas

Kyba

Ruby

Kuechly

et al. 2020

Lighting Research & Technology

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“…The other component is changed lighting behavior during the pandemic like switching off public lighting such as road lights or private lights from large businesses etc. This is very difficult to disentangle as shown in a recent large-scale switch-off experiment [30]. Nevertheless, the night sky brightness decreased by about 20% in a switch-off for ornamental lights in a town in Catalunya, Spain [28], by more than 5% in the city center when switching off streetlights in Tucson, Arizona, USA [30], and by about 8% during the WWF Earth Hour 2018 in Berlin, Germany [29].…”

Section: Discussionmentioning

confidence: 95%

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

Jechow

Hölker

2020

Remote Sensing

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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.

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“…One could, also, establish a value for the quiescent airglow level by adding up the minimum values for all known sources of diffuse night sky brightness.25 Methods Fig. 1: The vertical axis is the instrumental sky brightness, M(t), in mag/arcsec 2 . It shows changes in airglow due to solar activity at each sky position.…”

Section: Methods (Continued)mentioning

confidence: 99%

Linking Solar Minimum, Space Weather, and Night Sky Brightness

Grauer

A.²

2021

Preprint

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New observations indicate previously unrecognized significant sources of night sky brightness variations, not involving corresponding changes in the Sun's EUV flux , occur during deep solar minimum. Our data was taken at 5 sites spanning more than 8,500 km during the deep minimum of Solar Cycle 24 into the beginning of Solar Cycle 25. It shows; 1) Semi-annual night sky brightness variations are produced by interactions between the Earth's magnetic field and the interplanetary magnetic field. 2) Solar wind plasma streams from solar coronal holes produce major night sky brightness increase events. 3) Some night sky brightness events are relatively local. Others extend at least 8,500 km along the Earth's surface. 4) It is plausible, terrestrial night airglow and geomagnetic indices have similar responses to the solar energy input into Earth's magnetosphere. Our empirical results contribute to a quantitative basis for understanding and predicting night sky brightness variations. They are applicable in astronomical, space weather, light pollution, biological, and recreational studies.

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Recovering the city street lighting fraction from skyglow measurements in a large-scale municipal dimming experiment

Cited by 23 publications

References 27 publications

Direct measurement of the contribution of street lighting to satellite observations of nighttime light emissions from urban areas

Direct measurement of the contribution of street lighting to satellite observations of nighttime light emissions from urban areas

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

Linking Solar Minimum, Space Weather, and Night Sky Brightness

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