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Author Kocifaj, M.; Wallner, S.; Solano-Lamphar, H.A.
Title An asymptotic formula for skyglow modelling over a large territory Type Journal Article
Year 2019 Publication Monthly Notices of the Royal Astronomical Society Abbreviated Journal
Volume (down) 485 Issue 2 Pages 2214-2224
Keywords Skyglow
Abstract An analytical framework to predict skyglow due to distant sources is presented, which can be applied to model sky brightness from the zenith toward the horizon along a vertical plane crossing the hemisphere in the azimuthal position of a light source. Although various powerful algorithms have been developed over the last few decades, the time needed for calculation grows exponentially with increasing size of the modelling domain. This is one of the key issues in skyglow computations, because the numerical accuracy improves only slowly as the modelling domain extends. We treat the problem theoretically, by introducing an analytical formula that is well-suited for light sources located at intermediate and long distances from an observation point and allows tremendous time savings in numerical analyses, while keeping the error at a low level. Field experiments carried out in Eastern Austria provided a unique opportunity to validate the model using real-sky luminance data. The fact that the theoretical model allows the prediction of sky luminance within an acceptable error tolerance is not only in line with the experimental data, but also provides new means of remote characterization of light emissions from artificial sources. The method is particularly attractive for rapid and simple retrieval of the amount of light escaping upwards from the dominant light sources surrounding the observation point. We expect that the method can advance the numerical modelling of skyglow substantially, because it allows real-time computations for very large territories.
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ISSN 0035-8711 ISBN Medium
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Notes Approved no
Call Number GFZ @ kyba @ Serial 2258
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Author Aubé, M.; Simoneau, A.; Wainscoat, R.; Nelson, L.
Title Modeling the effects of phosphor converted LED lighting to the night sky of the Haleakala Observatory, Hawaii Type Journal Article
Year 2018 Publication Monthly Notices of the Royal Astronomical Society Abbreviated Journal
Volume (down) 478 Issue 2 Pages 1776-1783
Keywords Skyglow
Abstract The goal of this study is to evaluate the current level of light pollution in the night sky at the Haleakala Observatory on the island of Maui in Hawaii. This is accomplished with a numerical model that was tested in the first International Dark Sky Reserve located in Mont-Mégantic National Park in Canada. The model uses ground data on the artificial light sources present in the region of study, geographical data, and remotely sensed data for: 1) the nightly upward radiance; 2) the terrain elevation; and, 3) the ground spectral reflectance of the region. The results of the model give a measure of the current state of the sky spectral radiance at the Haleakala Observatory. Then, using the current state as a reference point, multiple light conversion plans are elaborated and evaluated using the model. We can thus estimate the expected impact of each conversion plan on the night sky radiance spectrum. A complete conversion to white (LEDs) with (CCT) of 4000K and 3000K are contrasted with a conversion using (PC) amber (LEDs). We include recommendations concerning the street lamps to be used in sensitive areas like the cities of Kahului and Kihei and suggest best lighting practices related to the color of lamps used at night.
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ISSN 0035-8711 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number GFZ @ kyba @ Serial 1907
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Author Kennard, D.C.; Chamberlin, V.D.
Title All-night Light for Layers Type Report
Year 1931 Publication Abbreviated Journal
Volume (down) Bulletin 476 Issue Pages
Keywords Animals
Abstract
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Corporate Author Ohio Agricultural Experiment Station Thesis
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Notes Approved no
Call Number GFZ @ kyba @ Serial 2392
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Author Bará, S.
Title Characterizing the zenithal night sky brightness in large territories: how many samples per square kilometre are needed? Type Journal Article
Year 2017 Publication Monthly Notices of the Royal Astronomical Society Abbreviated Journal
Volume (down) 473 Issue 3 Pages 4164-4173
Keywords Instrumentation; atmospheric effects; light pollution; numerical methods; photometry
Abstract A recurring question arises when trying to characterize, by means of measurements or theoretical calculations, the zenithal night sky brightness throughout a large territory: how many samples per square kilometre are needed? The optimum sampling distance should allow reconstructing, with sufficient accuracy, the continuous zenithal brightness map across the whole region, whilst at the same time avoiding unnecessary and redundant oversampling. This paper attempts to provide some tentative answers to this issue, using two complementary tools: the luminance structure function and the Nyquist–Shannon spatial sampling theorem. The analysis of several regions of the world, based on the data from the New world atlas of artificial night sky brightness, suggests that, as a rule of thumb, about one measurement per square kilometre could be sufficient for determining the zenithal night sky brightness of artificial origin at any point in a region to within ±0.1 magV arcsec–2 (in the root-mean-square sense) of its true value in the Johnson–Cousins V band. The exact reconstruction of the zenithal night sky brightness maps from samples taken at the Nyquist rate seems to be considerably more demanding.
Address 1Departamento de Física Aplicada, Universidade de Santiago de Compostela, E-15782 Santiago de Compostela, Galicia, Spain; salva.bara(at)usc.es
Corporate Author Thesis
Publisher Oxford Academic Place of Publication Editor
Language English Summary Language English Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0035-8711 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number IDA @ john @ Serial 2164
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Author Kocifaj, M.; Solano Lamphar, H.A.
Title Quantitative analysis of night skyglow amplification under cloudy conditions Type Journal Article
Year 2014 Publication Monthly Notices of the Royal Astronomical Society Abbreviated Journal Monthly Notices of the Royal Astronomical Society
Volume (down) 443 Issue 4 Pages 3665-3674
Keywords Skyglow; radiative transfer; scattering; atmospheric effects; light pollution; methods: numerical
Abstract The radiance produced by artificial light is a major source of nighttime over-illumination. It can, however, be treated experimentally using ground-based and satellite data. These two types of data complement each other and together have a high information content. For instance, the satellite data enable upward light emissions to be normalized, and this in turn allows skyglow levels at the ground to be modelled under cloudy or overcast conditions. Excessive night lighting imposes an unacceptable burden on nature, humans and professional astronomy. For this reason, there is a pressing need to determine the total amount of downwelling diffuse radiation. Undoubtedly, cloudy periods can cause a significant increase in skyglow as a result of amplification owing to diffuse reflection from clouds. While it is recognized that the amplification factor (AF) varies with cloud cover, the effects of different types of clouds, of atmospheric turbidity and of the geometrical relationships between the positions of an individual observer, the cloud layer, and the light source are in general poorly known. In this paper the AF is quantitatively analysed considering different aerosol optical depths (AODs), urban layout sizes and cloud types with specific albedos and altitudes. The computational results show that the AF peaks near the edges of a city rather than at its centre. In addition, the AF appears to be a decreasing function of AOD, which is particularly important when modelling the skyglow in regions with apparent temporal or seasonal variability of atmospheric turbidity. The findings in this paper will be useful to those designing engineering applications or modelling light pollution, as well as to astronomers and environmental scientists who aim to predict the amplification of skyglow caused by clouds. In addition, the semi-analytical formulae can be used to estimate the AF levels, especially in densely populated metropolitan regions for which detailed computations may be CPU-intensive. These new results are of theoretical and experimental significance as they will motivate experimentalists to collect data from various regions to build an overall picture of the AF, and will encourage modellers to test the consistency with theoretical predictions.
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ISSN 0035-8711 ISBN Medium
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Notes Approved no
Call Number LoNNe @ christopher.kyba @ Serial 538
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