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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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Call Number LoNNe @ christopher.kyba @ Serial 538
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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 (down) 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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ISSN 0035-8711 ISBN Medium
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Notes Approved no
Call Number IDA @ john @ Serial 326
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Author Sciezor, T.
Title A new astronomical method for determining the brightness of the night sky and its application to study long-term changes in the level of light pollution Type Journal Article
Year 2013 Publication Monthly Notices of the Royal Astronomical Society Abbreviated Journal Monthly Notices of the Royal Astronomical Society
Volume (down) 435 Issue 1 Pages 303-310
Keywords light pollution methods; data analysis methods; observational site testing; comets; measurements; light pollution; skyglow
Abstract In this paper, I present a new method that has been developed for determining the brightness of a cloudless night sky, on the basis of widely available amateur observations of comets. The tests show the correctness of the method, which makes it possible to determine the level of light pollution, defined as the brightness of the artificial sky glow, through the use of the archival observations of comets. The use of data bases of comet observations in Poland in the period 1994–2009 has led to a positive verification of the known model map of the brightness of the night sky. Also, it has been possible to find changes in the level of light pollution in this period, at the selected observation sites.
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ISSN 0035-8711 ISBN Medium
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Notes Approved no
Call Number IDA @ john @ Serial 266
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Author Foster, R.G.
Title Neurobiology: bright blue times Type Journal Article
Year 2005 Publication Nature Abbreviated Journal Nature
Volume (down) 433 Issue 7027 Pages 698-699
Keywords Human Health; Animals; Circadian Rhythm/physiology/radiation effects; Color Perception/physiology/*radiation effects; Humans; *Light; Light Signal Transduction/*radiation effects; Mice; Retinal Ganglion Cells/cytology/physiology/radiation effects; Retinaldehyde/chemistry/metabolism; Rod Opsins/*metabolism; NASA Discipline Space Human Factors; Non-NASA Center
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Language English Summary Language Original Title
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ISSN 0028-0836 ISBN Medium
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Notes PMID:15716938 Approved no
Call Number LoNNe @ kagoburian @ Serial 750
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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 (down) 427 Issue 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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