A Project Useful for Starry Sky Protection by Collaboration between Night Time Artificial Light Observation from Space and Night Sky Brightness Observation on the Ground

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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Estimating the relative contribution of streetlights, vehicles, and residential lighting to the urban night sky brightness

Lighting Research and Technology ◽

10.1177/1477153518808337 ◽

2018 ◽

Vol 51 (7) ◽

pp. 1092-1107 ◽

Cited By ~ 14

Author(s):

S Bará ◽

Á Rodríguez-Arós ◽

M Pérez ◽

B Tosar ◽

RC Lima ◽

...

Keyword(s):

Time Course ◽

Residential Buildings ◽

Artificial Light ◽

Light Sources ◽

Wide Field ◽

Atmospheric Conditions ◽

Least Squares Fit ◽

Sky Brightness ◽

Night Sky ◽

Night Sky Brightness

Under stable atmospheric conditions the brightness of the urban sky varies throughout the night following the time course of the anthropogenic emissions of light. Different types of artificial light sources (e.g. streetlights, residential, and vehicle lights) have specific time signatures, and this feature makes it possible to estimate the amount of brightness contributed by each of them. Our approach is based on transforming the time representation of the zenithal night sky brightness into a modal expansion in terms of the time signatures of the different sources of light. The modal coefficients, and hence the absolute and relative contributions of each type of source, can be estimated by means of a linear least squares fit. A practical method for determining the time signatures of different contributing sources is also described, based on wide-field time-lapse photometry of the urban nightscape. Our preliminary results suggest that, besides the dominant streetlight contribution, artificial light leaking out of the windows of residential buildings may account for a significant share of the time-varying part of the zenithal night sky brightness at the measurement locations, whilst the contribution of the vehicle lights seems to be significantly smaller.

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Night-time monitoring of the aerosol content of the lower atmosphere by differential photometry of the anthropogenic skyglow

Monthly Notices of the Royal Astronomical Society Letters ◽

10.1093/mnrasl/slaa181 ◽

2020 ◽

Vol 500 (1) ◽

pp. L47-L51

Author(s):

Miroslav Kocifaj ◽

Salvador Bará

Keyword(s):

Aerosol Optical Depth ◽

Optical Depth ◽

Single Channel ◽

Lower Atmosphere ◽

Light Sources ◽

Night Time ◽

Direct Estimate ◽

Sky Brightness ◽

Night Sky ◽

Night Sky Brightness

ABSTRACT Night-time monitoring of the aerosol content of the lower atmosphere is a challenging task, because appropriate reference natural light sources are lacking. Here, we show that the anthropogenic night-sky brightness due to city lights can be successfully used for estimating the aerosol optical depth of arbitrarily thick atmospheric layers. This method requires measuring the zenith night-sky brightness with two detectors located at the limiting layer altitudes. Combined with an estimate of the overall atmospheric optical depth (available from ground-based measurements or specific satellite products), the ratio of these radiances provides a direct estimate of the differential aerosol optical depth of the air column between these two altitudes. These measurements can be made with single-channel low-cost radiance detectors widely used by the light pollution research community.

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Living Environmental Laboratory for Lighting — A comprehensive study of interactions of artificial lighting and wildlifes

10.5194/egusphere-egu2020-6065 ◽

2020 ◽

Author(s):

Kai Pong Tong ◽

Zoltán Kolláth

Keyword(s):

National Parks ◽

Light Pollution ◽

Artificial Light ◽

Human Beings ◽

Pollution Research ◽

Environmental Laboratory ◽

Sky Brightness ◽

Night Sky ◽

The Impact ◽

Night Sky Brightness

Artificial light at night (ALAN) has become a major concern in recent years due to its impact on the health of human beings and the ecosystems. As a result, there is a surge of light pollution research not only on night sky brightness, but also on assessments of impacts on both ecology and society.We have set up an interdisciplinary project in Hungary since September 2017, to not only study the impacts of change in lighting technology on patterns of ALAN (with emphasis on the areas within and around national parks in Hungary), but also facilitate national and international cooperations in light pollution research. We refer to this project as Living Environmental Laboratory for Lighting (LELL). Specifically, the project covers the following areas:1. Development of new techniques for night sky radiometry and spectrometry We are developing techniques for night sky multispectral measurements using commercially available cameras with interchangeable lens, calibrated by high sensitivity spectroradiometer, in order to quantify night sky condition and identify sources of artificial light at high resolution not achieveable by systems based on panchromatic sensors or fisheye lenses. In addition, we will compare the results from our ground-based measurements with satellite-based observations.2. Modeling of night sky patterns in national parks of Hungary We have developed a Monte-Carlo method of modeling light pollution, which can also be used for investigating effects of aerosols and clouds on the propagation of artificial light.3. Impact assessments of ALAN through measurements The public lighting was remodeled to LED-based systems in two areas close to national parks, one of which in the Zselic region in Southwestern Hungary, and another in B&#252;kk in Northern Hungary. Using the techniques above, we are monitoring the change in night sky brightness and color, as well as the impact on flora and fauna.4. Recommendations on future assessments and mitigations of light pollution With our experience gain within the duration of this project, we will inform the light pollution research community of standardizing methodologies for monitoring light pollution, as well as giving recommendations for managing public lighting assets to reduce the impacts of light pollution. Acknowledgement This project is supported by the European Union and co-financed by the European Social Fund (Grant no. EFOP&#8211;3.6.2&#8211;16&#8211;201&#8211;00014: Development of international research environment for light pollution studies)

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Worldwide variations in artificial skyglow

Scientific Reports ◽

10.1038/srep08409 ◽

2015 ◽

Vol 5 (1) ◽

Cited By ~ 79

Author(s):

Christopher C. M. Kyba ◽

Kai Pong Tong ◽

Jonathan Bennie ◽

Ignacio Birriel ◽

Jennifer J. Birriel ◽

...

Keyword(s):

Monitoring Program ◽

Artificial Light ◽

Clear Sky ◽

International Monitoring ◽

Sky Brightness ◽

Ground Truthing ◽

Study Sites ◽

Night Sky Brightness ◽

Key Questions

Abstract Despite constituting a widespread and significant environmental change, understanding of artificial nighttime skyglow is extremely limited. Until now, published monitoring studies have been local or regional in scope and typically of short duration. In this first major international compilation of monitoring data we answer several key questions about skyglow properties. Skyglow is observed to vary over four orders of magnitude, a range hundreds of times larger than was the case before artificial light. Nearly all of the study sites were polluted by artificial light. A non-linear relationship is observed between the sky brightness on clear and overcast nights, with a change in behavior near the rural to urban landuse transition. Overcast skies ranged from a third darker to almost 18 times brighter than clear. Clear sky radiances estimated by the World Atlas of Artificial Night Sky Brightness were found to be overestimated by ~25%; our dataset will play an important role in the calibration and ground truthing of future skyglow models. Most of the brightly lit sites darkened as the night progressed, typically by ~5% per hour. The great variation in skyglow radiance observed from site-to-site and with changing meteorological conditions underlines the need for a long-term international monitoring program.

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A survey of night sky brightness at College, Alaska

Transactions American Geophysical Union ◽

10.1029/tr031i004p00541 ◽

1950 ◽

Vol 31 (4) ◽

pp. 541 ◽

Cited By ~ 1

Author(s):

John B. Wilcox

Keyword(s):

Sky Brightness ◽

Night Sky ◽

Night Sky Brightness

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Remote Sensing of Aerosols at Night with the CoSQM Sky Brightness Data

10.20944/preprints202108.0181.v1 ◽

2021 ◽

Author(s):

Charles Marseille ◽

Martin Aubé ◽

Africa Barreto Velasco ◽

Alexandre Simoneau

Keyword(s):

Remote Sensing ◽

Aerosol Optical Depth ◽

Optical Depth ◽

Low Cost ◽

Empirical Relationship ◽

Important Indicator ◽

Sky Brightness ◽

Night Sky ◽

Remote Sensing Techniques ◽

Night Sky Brightness

The aerosol optical depth is an important indicator of aerosol particle properties and associated radiative impacts. AOD determination is therefore very important to achieve relevant climate modeling. Most remote sensing techniques to retrieve aerosol optical depth are applicable to daytime given the high level of light available. The night represents half of the time but in such conditions only a few remote sensing techniques are available. Among these techniques, the most reliable are moon photometers and star photometers. In this paper, we attempt to fill gaps in the aerosol detection performed with the aforementioned techniques using night sky brightness measurements during moonless nights with the novel CoSQM: a portable, low cost and open-source multispectral photometer. In this paper, we present an innovative method for estimating the aerosol optical depth by using an empirical relationship between the zenith night sky brightness measured at night with the CoSQM and the aerosol optical depth retrieved at daytime from the AErosol Robotic NETwork. Such a method is especially suited to light-polluted regions with light pollution sources located within a few kilometers of the observation site. A coherent day-to-night aerosol optical depth and Ångström Exponent evolution in a set of 354 days and nights from August 2019 to February 2021 was verified at the location of Santa Cruz de Tenerife on the island of Tenerife, Spain. The preliminary uncertainty of this technique was evaluated using the variance under stable day-to-night conditions, set at 0.02 for aerosol optical depth and 0.75 for Ångström Exponent. These results indicate the set of CoSQM and the proposed methodology appear to be a promising tool to add new information on the aerosol optical properties at night, which could be of key importance to improve climate predictions.

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