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Author Kolláth, Z.; Kránicz, B.
Title On the feasibility of inversion methods based on models of urban sky glow Type Journal Article
Year 2014 Publication Journal of Quantitative Spectroscopy and Radiative Transfer Abbreviated Journal Journal of Quantitative Spectroscopy and Radiative Transfer
Volume 139 Issue Pages 27-34
Keywords Light pollution; Radiative transfer; Light scattering
Abstract Multi-wavelength imaging luminance photometry of sky glow provides a huge amount of information on light pollution. However, the understanding of the measured data involves the combination of different processes and data of radiation transfer, atmospheric physics and atmospheric constitution. State-of-the-art numerical radiation transfer models provide the possibility to define an inverse problem to obtain information on the emission intensity distribution of a city and perhaps the physical properties of the atmosphere. We provide numerical tests on the solvability and feasibility of such procedures.
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Publisher Place of Publication Editor
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Series Editor Series Title Abbreviated Series Title
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ISSN 0022-4073 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number IDA @ john @ Serial 179
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Author Kocifaj, M.
Title Modeling the night-sky radiances and inversion of multi-angle and multi-spectral radiance data Type Journal Article
Year 2014 Publication Journal of Quantitative Spectroscopy and Radiative Transfer Abbreviated Journal Journal of Quantitative Spectroscopy and Radiative Transfer
Volume 139 Issue Pages 35-42
Keywords Sky-glow; Light pollution; Aerosols; Light scattering; Inverse problems
Abstract Information on a city's emission pattern is crucial for any reasonable predictions of night sky radiances. Unfortunately, the bulk radiant intensity distribution as a function of zenith angle is scarcely available for any city throughout the world. Even if the spatial arrangements of urban light fixtures and lamp specifications are known, the cumulative effect on upwardly directed beams is difficult to determine; due to heterogeneity of the ambient environment, reflectance from ground surfaces, arbitrarily scattered obstacles, orography of terrain and many other site specific factors.

The present paper develops a theoretical model and a numerical technique applicable to the retrieval of a City Emission Function (CEF) from the spectral sky radiances measured under clear sky conditions. Mathematically it is an inverse problem that is solved using a regularization algorithm in which the minimization routines penalize non-smooth solutions and the radiant intensity pattern is found subject to regularizing constraints.

When spectral sky radiances are measured at a set of discrete wavelengths or at a set of discrete distances from the monitored light source, both the aerosol optical properties and the CEF can be determined concurrently. One great advantage of this approach is that no a-priori assumptions need to be made concerning aerosol properties, such as aerosol optical depth.

The numerical experiment on synthetically generated city emissions' patterns has proven the functionality of the method presented.
Address ICA, Slovak Academy of Sciences, Dúbravská Road 9, 845 03 Bratislava, Slovakia.
Corporate Author Thesis
Publisher Place of Publication Editor
Language (up) Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-4073 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number IDA @ john @ Serial 180
Permanent link to this record
 

 
Author Kocifaj, M.
Title Night sky luminance under clear sky conditions: Theory vs. experiment Type Journal Article
Year 2014 Publication Journal of Quantitative Spectroscopy and Radiative Transfer Abbreviated Journal Journal of Quantitative Spectroscopy and Radiative Transfer
Volume 139 Issue Pages 43-51
Keywords Sky glow; Luminance; Luminaire; City emission function; Anthropogenic; Single scattering; Inverse problems
Abstract Sky glow is caused by both natural phenomena and factors of anthropogenic origin, and of the latter ground-based light sources are the most important contributors for they emit the spatially linked spectral radiant intensity distribution of artificial light sources, which are further modulated by local atmospheric optics and perceived as the diffuse light of a night sky. In other words, sky glow is closely related to a city's shape and pattern of luminaire distribution, in practical effect an almost arbitrary deployment of random orientation of heterogeneous electrical light sources. Thus the luminance gradation function measured in a suburban zone or near the edges of a city is linked to the City Pattern or vice versa.

It is shown that clear sky luminance/radiance data recorded in an urban area can be used to retrieve the bulk luminous/radiant intensity distribution if some a-priori information on atmospheric aerosols is available. For instance, the single scattering albedo of aerosol particles is required under low turbidity conditions, as demonstrated on a targeted experiment in the city of Frýdek-Mistek. One of the main advantages of the retrieval method presented in this paper is that the single scattering approximation is satisfactorily accurate in characterizing the light field near the ground because the dominant contribution to the sky glow has originated from beams propagated along short optical paths.
Address ICA, Slovak Academy of Sciences, Dúbravská Road 9, 845 03 Bratislava, Slovakia
Corporate Author Thesis
Publisher Place of Publication Editor
Language (up) Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-4073 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number IDA @ john @ Serial 181
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Author Puschnig, J.; Posch, T.; Uttenthaler, S.
Title Night sky photometry and spectroscopy performed at the Vienna University Observatory Type Journal Article
Year 2014 Publication Journal of Quantitative Spectroscopy and Radiative Transfer Abbreviated Journal Journal of Quantitative Spectroscopy and Radiative Transfer
Volume 139 Issue Pages 64-75
Keywords Atmospheric effects; Site testing; Light pollution; Techniques: photometric; Techniques: spectroscopic
Abstract We present night sky brightness measurements performed at the Vienna University Observatory and at the Leopold-Figl-Observatorium für Astrophysik, which is located about 35 km to the southwest of Vienna. The measurements have been performed with Sky Quality Meters made by Unihedron. They cover a time span of roughly one year and have been carried out every night, yielding a luminance value every 7 s and thus delivering a large amount of data. In this paper, the level of skyglow in Vienna, which ranges from 15 to 19.25 magSQM arcsec−2 is presented for the very first time in a systematic way. We discuss the influence of different environmental conditions on the night sky brightness and implications for human vision. We show that the circalunar rhythm of night sky brightness is almost extinguished at our observatory due to light pollution.

Additionally, we present spectra of the night sky in Vienna, taken with a 0.8 m telescope. The goal of these spectroscopic measurements was to identify the main types of light sources and the spectral lines which cause the skyglow in Vienna. It turned out that fluorescent lamps are responsible for the strongest lines of the night sky above Vienna (e.g. lines at 546 nm and at 611 nm).
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Publisher Place of Publication Editor
Language (up) Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-4073 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number IDA @ john @ Serial 183
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Author Puschnig, J.; Schwope, A.; Posch, T.; Schwarz, R.
Title The night sky brightness at Potsdam-Babelsberg including overcast and moonlit conditions Type Journal Article
Year 2014 Publication Journal of Quantitative Spectroscopy and Radiative Transfer Abbreviated Journal Journal of Quantitative Spectroscopy and Radiative Transfer
Volume 139 Issue Pages 76-81
Keywords Atmospheric effects; Site testing; Light pollution; Techniques: photometric
Abstract We analyze the results of 2 years (2011–2012) of night sky photometry performed at the Leibniz Institute for Astrophysics in Potsdam-Babelsberg. This institute is located 23 km to the southwest of the center of Berlin. Our measurements have been performed with a Sky Quality Meter. We find night sky brightness values ranging from 16.5 to 20.3 magSQM arcsec−2; the latter value corresponds to 4.8 times the natural zenithal night sky brightness. We focus on the influence of clouds and of the moon on the night sky brightness. It turns out that Potsdam-Babelsberg, despite its proximity to Berlin, still shows a significant correlation of the night sky brightness with the lunar phases. However, the light-pollution-enhancing effect of clouds dominates the night sky brightness by far: overcast nights (up to 16.5 magSQM arcsec−2) are much brighter than clear full moon nights (18–18.5 magSQM arcsec−2).
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language (up) Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-4073 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number IDA @ john @ Serial 184
Permanent link to this record