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Aubé, M., & Roby, J. (2014). Sky brightness levels before and after the creation of the first International Dark Sky Reserve, Mont-Mégantic Observatory, Québec, Canada. JQSRT, 139, 52–63.
Abstract: In 2007, the area around the Mont-Mégantic Observatory (MMO) was officially certified by the International Dark-Sky Association and the Royal Astronomy Association of Canada as the first International Dark Sky Reserve (IDSR). In order to be able to investigate the impact of Artificial Light at Night on night sky brightness before and after the establishment of the IDSR, we used a heterogeneous artificial sky brightness model including an implicit calculation of 2nd order scattering (ILLUMINA) developed by Martin Aubé's group. This model generates three kinds of outputs: the sky radiance at the given site, observing angle and wavelength and the corresponding contribution and sensitivity maps. The maps allow for the identification of the origin of the sky radiance according to each part of the surrounding territory. For summer clear sky conditions, the results show that replacing light fixtures within a 25 km radius around the MMO with cut-off High Pressure Sodium devices and reducing the total installed radiant power to ~40% of its initial level are very efficient ways of reducing artificial sky brightness. The artificial sky brightness reduction at zenith observed after the establishment of the IDSR was ~50% in the 546 nm mercury spectral line, while the reduction obtained in the 569 nm sodium line was ~30%. A large part of that reduction can be associated to the reduction in radiant power. The contribution and sensitivity maps highlight critical zones where any changes in the lighting infrastructure have the most important impact on sky brightness at the MMO. Contribution and sensitivity maps have been used to analyze the detailed origin of sky brightness reduction. The results of this study are intended to support authorities in the management of their lighting infrastructure with the goal of reducing sky brightness. The results have been shared with MMO officials and are being used as a tool to improve sky quality at the observatory.
Keywords: Skyglow; measurements; metrology; Mont-Mégantic; Quebec; Canada; modelling; radiative transfer; sky quality; sky brightness
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Cao, C., & Bai, Y. (2014). Quantitative Analysis of VIIRS DNB Nightlight Point Source for Light Power Estimation and Stability Monitoring. Remote Sensing, 6(12), 11915–11935.
Abstract: The high sensitivity and advanced onboard calibration on the Visible Infrared Imaging Radiometer Suite (VIIRS) Day/Night Band (DNB) enables accurate measurements of low light radiances which leads to enhanced quantitative applications at night. The finer spatial resolution of DNB also allows users to examine social economic activities at urban scales. Given the growing interest in the use of the DNB data, there is a pressing need for better understanding of the calibration stability and absolute accuracy of the DNB at low radiances. The low light calibration accuracy was previously estimated at a moderate 15% using extended sources while the long-term stability has yet to be characterized. There are also several science related questions to be answered, for example, how the Earth’s atmosphere and surface variability contribute to the stability of the DNB measured radiances; how to separate them from instrument calibration stability; whether or not SI (International System of Units) traceable active light sources can be designed and installed at selected sites to monitor the calibration stability, radiometric and geolocation accuracy, and point spread functions of the DNB; furthermore, whether or not such active light sources can be used for detecting environmental changes, such as aerosols. This paper explores the quantitative analysis of nightlight point sources, such as those from fishing vessels, bridges, and cities, using fundamental radiometry and radiative transfer, which would be useful for a number of applications including search and rescue in severe weather events, as well as calibration/validation of the DNB. Time series of the bridge light data are used to assess the stability of the light measurements and the calibration of VIIRS DNB. It was found that the light radiant power computed from the VIIRS DNB data matched relatively well with independent assessments based on the in situ light installations, although estimates have to be made due to limited ground truth data and lack of suitable radiative transfer models. Results from time series analysis are encouraging in potentially being able to detect anomalies in the DNB calibration. The study also suggests that accurate ground based active lights, when properly designed and installed, can be used to monitor the stability of the VIIRS DNB calibration at near the specified minimum radiances (3 nW/cm^2/sr), and potentially can be used to monitor the environmental changes as well.
Keywords: Remote Sensing; light pollution; skyglow; VIIRS; VIIRS DNB; Suomi NPP; radiometry; radiative transfer; modelling
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Kwarteng, E. V. S., Andam-Akorful, S. A., Kwarteng, A., Asare, D. - C. B., Quaye-Ballard, J. A., Osei, F. B., et al. (2021). Spatial variation in lymphatic filariasis risk factors of hotspot zones in Ghana. BMC Public Health, 21(1), 230.
Abstract: BACKGROUND: Lymphatic Filariasis (LF), a parasitic nematode infection, poses a huge economic burden to affected countries. LF endemicity is localized and its prevalence is spatially heterogeneous. In Ghana, there exists differences in LF prevalence and multiplicity of symptoms in the country's northern and southern parts. Species distribution models (SDMs) have been utilized to explore the suite of risk factors that influence the transmission of LF in these geographically distinct regions. METHODS: Presence-absence records of microfilaria (mf) cases were stratified into northern and southern zones and used to run SDMs, while climate, socioeconomic, and land cover variables provided explanatory information. Generalized Linear Model (GLM), Generalized Boosted Model (GBM), Artificial Neural Network (ANN), Surface Range Envelope (SRE), Multivariate Adaptive Regression Splines (MARS), and Random Forests (RF) algorithms were run for both study zones and also for the entire country for comparison. RESULTS: Best model quality was obtained with RF and GBM algorithms with the highest Area under the Curve (AUC) of 0.98 and 0.95, respectively. The models predicted high suitable environments for LF transmission in the short grass savanna (northern) and coastal (southern) areas of Ghana. Mainly, land cover and socioeconomic variables such as proximity to inland water bodies and population density uniquely influenced LF transmission in the south. At the same time, poor housing was a distinctive risk factor in the north. Precipitation, temperature, slope, and poverty were common risk factors but with subtle variations in response values, which were confirmed by the countrywide model. CONCLUSIONS: This study has demonstrated that different variable combinations influence the occurrence of lymphatic filariasis in northern and southern Ghana. Thus, an understanding of the geographic distinctness in risk factors is required to inform on the development of area-specific transmission control systems towards LF elimination in Ghana and internationally.
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Rybnikova, N., & Portnov, B. A. (2020). Testing the generality of economic activity models estimated by merging night-time satellite images with socioeconomic data. Advances in Space Research, 66(11), 2610–2620.
Abstract: Knowledge-based economic activities (aka quaternary industries or QIs) are characterized by high concentrations of labour force and potentially high night-time light emissions. Therefore, geographic concentrations of such activities can presumably be identified using information on the amount artificial light at night (ALAN), which different geographic areas emit. Question, however, remains whether the models, incorporating ALAN data, are place-specific or whether such models are sufficiently generic, thus making it possible to apply them, once estimated, to other countries and continents. To answer this question, the analysis is performed in several phases. First, we build separate models for European NUTS3 regions and US counties. Next, we cross-validate these models and use them to predict QI concentrations worldwide. As the analysis shows, cross-validation of the models, applied to the “counterpart” continent, also results in a reasonably good fit, with R2 reaching 0.852, when the US-model is applied to the EU data, and R2 = 0.896, when the EU-model is applied to the US data. Although attempts to use ALAN data for the analysis of different socio-economic phenomena are not new, to the best of our knowledge, this is the study first that uses cross-continent validation of ALAN-based models to determine their generality.
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Zissis, G. (2020). Sustainable Lighting and Light Pollution: A Critical Issue for the Present Generation, a Challenge to the Future. Sustainability, 12(11), 4552.
Abstract: Human beings’ poor night vision and primitive fear of the dark are reflected in an imperative need to use artificial light to illuminate their environment. Outdoor illumination undoubtedly contributes to the enhancement of practical opportunities for social and economic developments. Considered as a necessity, a means of security, and an attraction or valorization, city lighting growth has been literally exponential in the last half century. Beyond the financial and energy resources that it absorbs, the artificial lighting of urban spaces overflows its objective by polluting our nights to the point that, in our modern megacities, the stars disappear. Apart from the fact that stars are no longer visible, the scientific community is increasingly interested in the direct and indirect impacts of artificial lighting on biodiversity. In parallel, some studies have shown recently that stray light may have direct or indirect effects on human health and mood. The scope of this Special Issue, dedicated to the memory of Prof. Abraham Haim and Dr. Thomas Posch, is to put together a series of high-level papers treating light pollution in a holistic manner that goes from technological advances to policies, passing through impacts on biotopes and human health. Beyond its evident scientific interest, this Special Issue is also contributing to awareness raising, aimed at decision- and policy-makers.
Keywords: Society; light pollution measurement and modelling; light pollution impact on fauna and flora; light pollution impact on human health; policies to prevent/limit light pollution and territorial management; best practices for street lighting with low impact on light pollution; smart lighting and light pollution
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