| Records |
| Author |
Kocifaj, M. |
| Title |
Light-pollution model for cloudy and cloudless night skies with ground-based light sources |
Type  |
Journal Article |
| Year |
2007 |
Publication |
Applied Optics |
Abbreviated Journal |
Appl. Opt. |
| Volume |
46 |
Issue |
15 |
Pages |
3013 |
| Keywords |
light pollution; modeling |
| Abstract |
The scalable theoretical model of light pollution for ground sources is presented. The model is successfully employed for simulation of angular behavior of the spectral and integral sky radiance and∕or luminance during nighttime. There is no restriction on the number of ground-based light sources or on the spatial distribution of these sources in the vicinity of the measuring point (i.e., both distances and azimuth angles of the light sources are configurable). The model is applicable for real finite-dimensional surface sources with defined spectral and angular radiating properties contrary to frequently used point-source approximations. The influence of the atmosphere on the transmitted radiation is formulated in terms of aerosol and molecular optical properties. Altitude and spectral reflectance of a cloud layer are the main factors introduced for simulation of cloudy and∕or overcast conditions. The derived equations are translated into numerically fast code, and it is possible to repeat the entire set of calculations in real time. The parametric character of the model enables its efficient usage by illuminating engineers and∕or astronomers in the study of various light-pollution situations. Some examples of numerical runs in the form of graphical results are presented. |
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0003-6935 |
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IDA @ john @ |
Serial |
277 |
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| Author |
Xavier Kerola, D. |
| Title |
Modelling artificial night-sky brightness with a polarized multiple scattering radiative transfer computer code: Modelling artificial night-sky brightness |
Type |
Journal Article |
| Year |
2006 |
Publication |
Monthly Notices of the Royal Astronomical Society |
Abbreviated Journal |
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| Volume |
365 |
Issue |
4 |
Pages |
1295-1299 |
| Keywords |
Skyglow; modeling; radiative transfer; Gauss-Seidel; light pollution; Garstang model |
| Abstract |
As part of an ongoing investigation of radiative effects produced by hazy atmospheres, computational procedures have been developed for use in determining the brightening of the night sky as a result of urban illumination. The downwardly and upwardly directed radiances of multiply scattered light from an offending metropolitan source are computed by a straightforward Gauss-Seidel (G-S) iterative technique applied directly to the integrated form of Chandrasekhar's vectorized radiative transfer equation. Initial benchmark night-sky brightness tests of the present G-S model using fully consistent optical emission and extinction input parameters yield very encouraging results when compared with the double scattering treatment of Garstang, the only full-fledged previously available model. |
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0035-8711 |
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IDA @ john @ |
Serial |
278 |
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| Author |
Bará, S.; Nievas, M.; Sanchez de Miguel, A.; Zamorano, J. |
| Title |
Zernike analysis of all-sky night brightness maps |
Type |
Journal Article |
| Year |
2014 |
Publication |
Applied Optics |
Abbreviated Journal |
Appl Opt |
| Volume |
53 |
Issue |
12 |
Pages |
2677-2686 |
| Keywords |
modeling; light at night; light pollution; all-sky; Zernike polynomials; image decomposition; sky brightness |
| Abstract |
All-sky night brightness maps (calibrated images of the night sky with hemispherical field-of-view (FOV) taken at standard photometric bands) provide useful data to assess the light pollution levels at any ground site. We show that these maps can be efficiently described and analyzed using Zernike circle polynomials. The relevant image information can be compressed into a low-dimensional coefficients vector, giving an analytical expression for the sky brightness and alleviating the effects of noise. Moreover, the Zernike expansions allow us to quantify in a straightforward way the average and zenithal sky brightness and its variation across the FOV, providing a convenient framework to study the time course of these magnitudes. We apply this framework to analyze the results of a one-year campaign of night sky brightness measurements made at the UCM observatory in Madrid. |
| Address |
Ãrea de Óptica, Dept. de FÃsica Aplicada, Fac. de FÃsica, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Galicia, Spain |
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Optical Society of America |
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English |
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0003-6935 |
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PMID:24787595 |
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IDA @ john @ |
Serial |
318 |
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| Author |
Kocifaj, M.; Solano Lamphar, H.A. |
| Title |
Skyglow: a retrieval of the approximate radiant intensity function of ground-based light sources |
Type |
Journal Article |
| Year |
2014 |
Publication |
Monthly Notices of the Royal Astronomical Society |
Abbreviated Journal |
Monthly Notices of the Royal Astronomical Society |
| Volume |
439 |
Issue |
4 |
Pages |
3405-3413 |
| Keywords |
radiative transfer; atmospheric effects; light pollution; methods: observational; site testing; skyglow; modeling |
| Abstract |
The angular distribution of the light emitted from a city is an important source of information about public lighting systems and it also plays a key role in modelling the skyglow. Usually, the upwardly directed radiation is characterized through a parametrized emission function – a semi-empirical approach as a reasonable approximation that allows for fast computations. However, theoretical or experimental retrievals of emission characteristics are extremely difficult to obtain because of both the complexity of radiative transfer methods and/or the lack of highly specialized measuring devices.
Our research has been conducted with the specific objective to identify an efficient theoretical technique for retrieval of the emission pattern of ground-based light sources in order to determine the optimum values of the scaling parameters of the Garstang function. In particular, the input data involve the zenith luminance or radiance with horizontal illuminance or irradiance. Theoretical ratios of zenith luminance LV(0) to horizontal illuminance DV are calculated for a set of distances d that separate a hypothetical observer from the light source (a city or town). This approach is advantageous because inexpensive traditional equipment can be used to obtain the mean values of the Garstang parameters. Furthermore, it can also be applied to other parametrizable emission functions and to any measuring site, even one with a masked horizon. |
| Address |
Department of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University, Mlynská dolina, 842 48 Bratislava, Slovak Republic |
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0035-8711 |
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IDA @ john @ |
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326 |
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Troy, J.R.; Holmes, N.D.; Veech, J.A.; Green, M.C. |
| Title |
Using observed seabird fallout records to infer patterns of attraction to artificial light |
Type |
Journal Article |
| Year |
2013 |
Publication |
Endangered Species Research |
Abbreviated Journal |
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| Volume |
22 |
Issue |
3 |
Pages |
225-234 |
| Keywords |
Animals; Anthropogenic light; GIS-based modeling; Hawaii; Kauai; Light attraction; Procellariiformes; Newell’s shearwater; Seabird conservation |
| Abstract |
Attraction of fledgling shearwaters, petrels, and storm-petrels to artificial light has been documented for decades on islands around the world and is considered a significant threat to many species. Although large numbers of downed birds have been observed after being disoriented by light, several important elements of this ‘fallout’ phenomenon are unknown, including the locations along the path from nest to ocean at which attraction and/or disorientation occurs and whether fledglings can be attracted back to land after reaching the ocean in numbers large enough to contribute significantly to fallout. To investigate these questions, we compared observed Newell’s shearwater Puffinus newelli fallout records (from 1998 to 2009) on Kauai, USA, with expected numbers generated from several hypothetical models containing basic assumptions related to fledgling movement and attraction to light. Based on our results, the spatial pattern of observed fallout is consistent with the amount of light that fledglings may view along their first flights to and beyond the coastline. This suggests that even fledglings from dark regions of the island may not be safe because they may view light after reaching the ocean and still be susceptible to attraction. These findings support recent modeling efforts predicting that most birds fledging from Kauai are likely exposed to at least some anthropogenic light. As nocturnal use of light by humans is unlikely to be eliminated, research on the types of artificial light that are both useful to humans and safe for seabirds may be crucial for the conservation of these important marine animals. |
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LoNNe @ christopher.kyba @ |
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383 |
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