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Author (up) Kocifaj, M. url  doi
openurl 
  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  
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  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 (up) Kocifaj, M.; Kundracik, F. url  doi
openurl 
  Title Multi-wavelength radiometry of aerosols designed for more accurate night sky brightness predictions Type Journal Article
  Year 2020 Publication Journal of Quantitative Spectroscopy and Radiative Transfer Abbreviated Journal Journal of Quantitative Spectroscopy and Radiative Transfer  
  Volume 250 Issue Pages 106998  
  Keywords Skyglow; Remote Sensing  
  Abstract Scattering by aerosols and gases cause a certain fraction of artificial light emitted upwards is redirected to the ground. Of all atmospheric constituents just the aerosols are most important modulators of night-sky brightness under cloudless conditions. Unlike most of the previous we highlight a crucial role of solar radiometry for determining the atmospheric optical depth before night-time observation is to be made. Aerosol optical depth at visible wavelengths extracted from the data measured provides then the information on size distribution or mean refractive index of aerosol particles that in turn are both necessary to make night sky brightness prediction more accurate. Therefore, combining daytime and night-time radiometry we can achieve accuracy much higher than ever before. This is due to significantly reduced uncertainty in aerosol properties.

The aerosol data are retrieved from a new portable multi-wavelength optical analyzer that operates Ocean Optics spectrometer. The equipment provides the radiance data from 350 nm to 1000 nm with spectral resolution of 1 nm. Due to high sun radiance levels we use a system of mirrors each reducing the signal to about 4%, while keeping the integration time short. The minimum integration time of 3 ms allows for detection of direct sunlight. The system developed is sensitive to small changes in the aerosol system, while showing a good detection limit even under low turbidity conditions. The system performance is demonstrated in field experiment conducted shortly after front passage when most of aerosol particles is effectively removed by rain.
 
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  ISSN 0022-4073 ISBN Medium  
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  Notes Approved no  
  Call Number GFZ @ kyba @ Serial 2906  
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Author (up) Kolláth, K.; Kolláth, Z. url  doi
openurl 
  Title On the feasibility of using ceilometer backscatter profile as input data for skyglow simulation Type Journal Article
  Year 2020 Publication Journal of Quantitative Spectroscopy and Radiative Transfer Abbreviated Journal Journal of Quantitative Spectroscopy and Radiative Transfer  
  Volume in press Issue Pages in press  
  Keywords Skyglow; Instrumentation  
  Abstract Atmospheric conditions can significantly affect the sky brightness originating from artificial lights. Previous works studied the cloudiness, cloud base height, optical depth of cloud, aerosol optical depth and aerosol scale height as atmospheric parameters affecting night sky brightness. Instead of using these parameters as a simplification of the real cloud and aerosol profile, we processed the raw backscatter data of a laser ceilometer instrument. Sky brightness was obtained from camera images available at the same meteorological observation site. Case studies are shown in selected cases, where we analyzed the correspondences with the backscatter data and the camera images. We performed Monte Carlo simulations with the dominant light sources to verify the numerical predictions of sky radiances. Although the limitations of the ceilometer device to obtain optical properties of the atmosphere, ceilometers provide valuable source of data for evaluation of the light pollution measurements.  
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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 GFZ @ kyba @ Serial 2994  
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Author (up) Kolláth, Z.; Cool, A.; Jechow, A.; Kolláth, K.; Száz, D.; Tong, K.P. url  doi
openurl 
  Title Introducing the Dark Sky Unit for multi-spectral measurement of the night sky quality with commercial digital cameras Type Journal Article
  Year 2020 Publication Journal of Quantitative Spectroscopy and Radiative Transfer Abbreviated Journal Journal of Quantitative Spectroscopy and Radiative Transfer  
  Volume 253 Issue Pages 107162  
  Keywords Skyglow; Instrumentation; Measurement; light pollution; Radiometry  
  Abstract Multi-spectral imaging radiometry of the night sky provides essential information on light pollution (skyglow) and sky quality. However, due to the different spectral sensitivity of the devices used for light pollution measurement, the comparison of different surveys is not always trivial. In addition to the differences between measurement approaches, there is a strong variation in natural sky radiance due to the changes of airglow. Thus, especially at dark locations, the classical measurement methods (such as Sky Quality Meters) fail to provide consistent results. In this paper, we show how to make better use of the multi-spectral capabilities of commercial digital cameras and show their application for airglow analysis. We further recommend a novel sky quality metric the ”Dark Sky Unit”, based on an easily usable and SI traceable unit. This unit is a natural choice for consistent, digital camera-based measurements. We also present our camera system calibration methodology for use with the introduced metrics.  
  Address ELTE BDPK, Szombathely, Department of Physics, Hungary; zkollath(at)gmail.com  
  Corporate Author Thesis  
  Publisher Elsever Place of Publication Elsevier Editor  
  Language English Summary Language English Original Title  
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  ISSN 0022-4073 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number IDA @ john @ Serial 2998  
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Author (up) Kolláth, Z.; Dömény, A.; Kolláth, K.; Nagy, B. url  doi
openurl 
  Title Qualifying lighting remodelling in a Hungarian city based on light pollution effects Type Journal Article
  Year 2016 Publication Journal of Quantitative Spectroscopy and Radiative Transfer Abbreviated Journal Journal of Quantitative Spectroscopy and Radiative Transfer  
  Volume 181 Issue Pages 46-51  
  Keywords Skyglow; Lighting  
  Abstract The public lighting system has been remodelled in several Hungarian cities. In some cases the majority of the old luminaries were fitted with high pressure sodium lamps and they were replaced with white LED lighting with a typical correlated colour temperature of about 4500 K. Therefore, these remodelling works provide a testbed for methods in measurements and modelling. We measured the luminance of the light domes of selected cities by DSLR photometry before and after the remodelling.

Thanks to the full cut off design of the new lighting fixtures we obtained a slight decrease even in the blue part of the sky dome spectra of a tested city. However, we have to note that this positive change is the result of the bad geometry (large ULR) of the previous lighting system. Based on Monte Carlo radiative transfer calculations we provide a comparison of different indicators that can be used to qualify the remodelling, and to predict the possible changes in light pollution.
 
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  Notes Approved no  
  Call Number LoNNe @ kyba @; GFZ @ kyba @ Serial 1375  
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