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Author Cinzano, P.; Falchi, F.
Title The propagation of light pollution in the atmosphere Type Journal Article
Year 2012 Publication Monthly Notices of the Royal Astronomical Society Abbreviated Journal Monthly Notices of the Royal Astronomical Society
Volume 427 Issue (up) 4 Pages 3337-3357
Keywords radiative transfer; scattering; atmospheric effects; light pollution; site testing; light at night; Garstang model; LPTRAN; DMSP-OLS; GTOPO30; modeling; propagation
Abstract Recent methods to map artificial night-sky brightness and stellar visibility across large territories or their distribution over the entire sky at any site are based on computation of the propagation of light pollution with Garstang models, a simplified solution of the radiative transfer problem in the atmosphere that allows fast computation by reducing it to a ray-tracing approach. They are accurate for a clear atmosphere, when a two-scattering approximation is acceptable, which is the most common situation. We present here up-to-date extended Garstang models (EGM), which provide a more general numerical solution for the radiative transfer problem applied to the propagation of light pollution in the atmosphere. We also present the LPTRAN software package, an application of EGM to high-resolution Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS) satellite measurements of artificial light emission and to GTOPO30 (Global 30 Arcsecond) digital elevation data, which provides an up-to-date method to predict the artificial brightness distribution of the night sky at any site in the world at any visible wavelength for a broad range of atmospheric situations and the artificial radiation density in the atmosphere across the territory. EGM account for (i) multiple scattering, (ii) wavelengths from 250 nm to infrared, (iii) the Earth's curvature and its screening effects, (iv) site and source elevation, (v) many kinds of atmosphere with the possibility of custom set-up (e.g. including thermal inversion layers), (vi) a mix of different boundary-layer aerosols and tropospheric aerosols, with the possibility of custom set-up, (vii) up to five aerosol layers in the upper atmosphere, including fresh and aged volcanic dust and meteoric dust, (viii) variations of the scattering phase function with elevation, (ix) continuum and line gas absorption from many species, ozone included, (x) up to five cloud layers, (xi) wavelength-dependent bidirectional reflectance of the ground surface from National Aeronautics and Space Administration (NASA) Moderate-Resolution Imaging Spectroradiometer (MODIS) satellite data, main models or custom data (snow included) and (xii) geographically variable upward light-emission function given as a three-parameter function or a Legendre polynomial series. Atmospheric scattering properties or light-pollution propagation functions from other sources can also be applied. A more general solution allows us to account also for (xiii) mountain screening, (xiv) geographical gradients of atmospheric conditions, including localized clouds and (xv) geographic distribution of ground surfaces, but suffers from too heavy computational requirements. Comparisons between predictions of classic Garstang models and EGM show close agreement for a US62 standard clear atmosphere and typical upward emission function.
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ISSN 0035-8711 ISBN Medium
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Notes Approved no
Call Number IDA @ john @ Serial 271
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Author Kocifaj, M.
Title Modelling the spectral behaviour of night skylight close to artificial light sources Type Journal Article
Year 2010 Publication Monthly Notices of the Royal Astronomical Society Abbreviated Journal MNRAS
Volume 403 Issue (up) 4 Pages 2105-2110
Keywords scattering; atmospheric effects; light pollution; methods: numerical; Modeling
Abstract Spectral features of the night sky are simulated under cloudless conditions. Numerical runs show that spectral composition of the diffuse light changes over the whole sky and sky radiances quickly respond to altering aerosol characteristics, such as the asymmetry parameter, single scattering albedo and total optical thickness. The general trend is a steep decrease of diffuse irradiance with a distance from the city centre. Powerstar HQI-NDL lamps produce more light at short wavelengths, thus implying the higher levels of light pollution. The red light may markedly contribute to the obtrusive light if Vialox NAV-4Y lamps are considered as a prevailing source of light in the model town. In a non-turbid atmosphere, the minimum radiance is notoriously observed close to the zenith. As aerosol loading increases, the minimum radiance is shifted to larger zenith angles at the opposite side of the light source. Obtained results may serve as corrections to spectrophotometry data, as the light pollution can be easily calculated for any sky element and for any spectral band.
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ISSN 0035-8711 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number IDA @ john @ Serial 276
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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
Volume 365 Issue (up) 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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Language Summary Language Original Title
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ISSN 0035-8711 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number IDA @ john @ Serial 278
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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 (up) 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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Notes Approved no
Call Number IDA @ john @ Serial 326
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Author Rea, M. S.; Bierman, A.
Title Spectral considerations for outdoor lighting: Consequences for sky glow Type Journal Article
Year 2014 Publication Lighting Research and Technology Abbreviated Journal Lighting Res. & Tech.
Volume 47 Issue (up) 8 Pages 920-930
Keywords Lighting; skyglow; spectrum; scattering; aerosol; modeling
Abstract It is well known that the magnitude of sky glow on a clear night depends upon the aerosol content in the atmosphere and the spectral power distribution (amount and spectrum). Sources with a greater proportion of short-wavelength radiation produce more backscattered radiation, but as aerosol density increases, the differential effect of spectrum becomes smaller. Sky glow magnitude also depends upon the operating characteristics of the detector and will be greater when the spectrum of the backscattered radiation is tuned to the spectral band-pass characteristics of the detector. The human visual system is most often used to assess sky glow magnitude, but its spectral response is not limited to a single, univariate detector. Rather, the retina is composed of many neural channels, each with its own spectral and absolute sensitivities to optical radiation. Since we can use a different neural channel to see an individual star than we do to gain an overall impression of sky brightness, changes to the spectral power distribution of backscattered radiation differentially, and simultaneously, affect one’s ability to see a single star and to assess sky brightness. A general method for assessing sky glow based upon aerosol content, spectral power distribution and the specific operating characteristics of a detector, human or otherwise, is offered.
Address Lighting Research Center, Rensselaer Polytechnic Institute, Troy, New York, USA
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Publisher The Society of Light and Lighting Place of Publication Editor
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Notes Approved no
Call Number IDA @ john @ Serial 1065
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