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Author Petržala, J.; Kocifaj, M. url  doi
openurl 
  Title Research on spectral factors towards determining nocturnal ground irradiance under overcast sky conditions in densely populated regions Type Journal Article
  Year 2017 Publication Journal of Quantitative Spectroscopy and Radiative Transfer Abbreviated Journal Journal of Quantitative Spectroscopy and Radiative Transfer  
  Volume 189 Issue Pages 126-132  
  Keywords Skyglow  
  Abstract Light pollution is closely correlated with the meteorological factors, specifically cloudiness that is one of the major amplifiers of night sky radiances in urban regions. Although the decisive effects of cloud deck on artificial nighttime skyglow have been recognized experimentally, the radiative transfer modelling in a heterogeneous nocturnal environment illuminated from many light sources is a non-trivial problem that is difficult to solve both theoretically and numerically. A satisfactorily accurate evaluation of ground-reaching diffuse light is, however, an important issue as some optical properties (e.g. horizontal irradiance) are usually difficult to obtain with common instruments. Overcast sky represents a special class of situations in which clouds can act as amplifiers of the light pollution of the city.

In this paper we proceeded with a simple two-stream approach to solve the scalar radiative transfer equation (RTE) under overcast conditions. The technique we are using allows for a rapid prediction of ground irradiances in densely populated regions assuming various emission functions. We have shown that the classical RTE concept can be adopted in determining the diffuse irradiance, while the model abilities are illustrated in a set of numerical experiments for low and high turbidity states.
 
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  Corporate Author Thesis  
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  Language Summary Language (up) 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 GFZ @ kyba @ Serial 2034  
Permanent link to this record
 

 
Author Kotarba, A.Z.; Chacewicz, S.; Żmudzka, E. url  doi
openurl 
  Title Night sky photometry over Warsaw (Poland) evaluated simultaneously with surface-based and satellite-based cloud observations Type Journal Article
  Year 2019 Publication Journal of Quantitative Spectroscopy and Radiative Transfer Abbreviated Journal Journal of Quantitative Spectroscopy and Radiative Transfer  
  Volume 235 Issue Pages 95-107  
  Keywords Skyglow  
  Abstract Light pollution is a widely distributed form of anthropogenic pollution that threatens both biodiversity and human health. One of the most popular indicators is known as night sky brightness (NSB), measured with photometric techniques. In the study, we report results of the very first, long-term photometric survey of NSB over Poland's capital, Warsaw, for 636 nights between 2014 and 2016 using a sky quality meter (SQM). Data were collected for all-weather conditions and, for the first time, we simultaneously use two independent sources of cloud amount data: surface-based (SYNOP) and satellite-based (Meteosat/SEVIRI). Results show that Warsaw is significantly polluted by light, with average NSB of 18.65 ± 0.06 magSQM/arcsec2 (15 times higher than unpolluted sky). Zenithal NSB is almost unaffected by moonlight. During astronomical nights, cloud cover was the dominant determinant of NSB, increasing by 7 times for overcast sky. In general, the sky brightened by ∼0.2 magSQM/arcsec2 for each 10% increase in cloud fraction. Satellite-based cloud amount data was found to be a very reliable alternative to traditional SYNOP observations. No statistically significant difference was found for average NSB calculated using satellite and SYNOP datasets. This finding is of particular importance, since the coverage of surface-based data is limited, while satellite observations can be obtained for any location on Earth, and collocate with any NSB photometric station. Our investigation also highlighted that SYNOP data are unreliable when cloud amount is low. This is due to the different fields of view for SQM (20°) and SYNOP (180°) observations of broken cloud.  
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  Language Summary Language (up) 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 GFZ @ kyba @ Serial 2580  
Permanent link to this record
 

 
Author Kocifaj, M. url  doi
openurl 
  Title Ground albedo impacts on higher-order scattering spectral radiances of night sky Type Journal Article
  Year 2019 Publication Journal of Quantitative Spectroscopy and Radiative Transfer Abbreviated Journal Journal of Quantitative Spectroscopy and Radiative Transfer  
  Volume 239 Issue Pages 106670  
  Keywords skyglow  
  Abstract The contribution from ground reflected light to the night sky radiance is of increased interest because of constant modernization of street lighting systems that now efficiently eliminate light emissions above the horizontal plane, so the appreciable fraction of artificial light directed upwards is from ground reflection. Diffuse light of a night sky shows a positive correlation with ground albedo (α), but it seems there is no linear trend between α and the night sky brightness (NSB), at least not for all sky elements, and, the mechanism of this relationship becomes even more complicated due to multiple scattering effects. The extent to which the ground reflectance influences the higher-order scattering radiance of night sky, and, the factors that initiate the crossover from single- to multiple-scattering dominance of the sky glow has been virtually unexplored until now.

We demonstrate here that albedo-induced effects in NSB exhibit an angular dependence, with amplitudes enhanced towards shorter wavelengths. For low values of ground reflectance and at short distances from a light source, the second-scattering radiance is found to be only a few percent of the first-order scattering radiance. However, the ratio of a higher- to the first-order scattering radiance gradually increases near horizon, specifically at the side opposite to the azimuthal position of the light source. Also the NSB in blue band has decreasing gradation tendency when increasing the altitude above sea level. The findings in this paper are significant in a proper incorporation of higher-order scattering in modeling the NSB under elevated reflectance conditions, and may be critical for saving computational time.
 
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  Language Summary Language (up) Original Title  
  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 2679  
Permanent link to this record
 

 
Author Bará, S.; Rigueiro, I.; Lima, R.C. url  doi
openurl 
  Title Monitoring transition: Expected night sky brightness trends in different photometric bands Type Journal Article
  Year 2019 Publication Journal of Quantitative Spectroscopy and Radiative Transfer Abbreviated Journal Journal of Quantitative Spectroscopy and Radiative Transfer  
  Volume 239 Issue Pages 106644  
  Keywords Skyglow; Remote Sensing; Instrumentation  
  Abstract Several light pollution indicators are commonly used to monitor the effects of the transition from outdoor lighting systems based on traditional gas-discharge lamps to solid-state light sources. In this work we analyze a subset of these indicators, including the artificial zenithal night sky brightness in the visual photopic and scotopic bands, the brightness in the specific photometric band of the widely used Sky Quality Meter (SQM), and the top-of-atmosphere radiance detected by the VIIRS-DNB radiometer onboard the satellite Suomi-NPP. Using a single-scattering approximation in a layered atmosphere we quantitatively show that, depending on the transition scenarios, these indicators may show different, even opposite behaviors. This is mainly due to the combined effects of the changes in the sources' spectra and angular radiation patterns, the wavelength-dependent atmospheric propagation processes and the differences in the detector spectral sensitivity bands. It is suggested that the possible presence of this differential behavior should be taken into account when evaluating light pollution indicator datasets for assessing the outcomes of public policy decisions regarding the upgrading of outdoor lighting systems.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language (up) 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 GFZ @ kyba @ Serial 2810  
Permanent link to this record
 

 
Author Min, M.; Zheng, J.; Zhang, P.; Hu, X.; Chen, L.; Li, X.; Huang, Y.; Zhu, L. url  doi
openurl 
  Title A low-light radiative transfer model for satellite observations of moonlight and earth surface light at night 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 106954  
  Keywords Remote Sensing; Instrumentation  
  Abstract Lunar sun-reflected light can be effectively measured through a low-light band or a day/night band (DNB) implemented on space-based optical sensors. Based on moonlight, nocturnal observations for artificial light sources at night can be achieved. However, to date, an open-sourced and mature Low-Light Radiative Transfer Model (LLRTM) for the further understanding of the radiative transfer problem at night is still unavailable. Therefore, this study develops a new LLRTM at night with the correction of the lunar and active surface light sources. First, the radiative transfer equations with an active surface light source are derived for the calculation based on the lunar spectral irradiance (LSI) model. The simulation from this new LLRTM shows a minimal bias when compared with the discrete ordinates radiative transfer (DISORT) model. The simulated results of radiance and reflectance at the top of the atmosphere (TOA) also show that the surface light source has a remarkable impact on the radiative transfer process. In contrast, the change in the lunar phase angle has minimal influence. Also, comparing with space-based DNB radiance observations, LLRTM shows the potential to simulate space-based low-light imager observations under an effective surface light source condition during the night.  
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  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language (up) 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 GFZ @ kyba @ Serial 2850  
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