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Author Noll, S.; Kausch, W.; Barden, M.; Jones, A.M.; Szyszka, C.; Kimeswenger, S.; Vinther, J. url  doi
openurl 
  Title An atmospheric radiation model for Cerro Paranal: I. The optical spectral range* Type Journal Article
  Year 2012 Publication Astronomy & Astrophysics Abbreviated Journal A&A  
  Volume (down) 543 Issue Pages A92  
  Keywords atmospheric effects; site testing; radiative transfer; radiation mechanisms: general; scattering; techniques; spectroscopic; modeling; observatories; Cerro Paranal  
  Abstract Aims. The Earth’s atmosphere affects ground-based astronomical observations. Scattering, absorption, and radiation processes deteriorate the signal-to-noise ratio of the data received. For scheduling astronomical observations it is, therefore, important to accurately estimate the wavelength-dependent effect of the Earth’s atmosphere on the observed flux.

Methods. In order to increase the accuracy of the exposure time calculator of the European Southern Observatory’s (ESO) Very Large Telescope (VLT) at Cerro Paranal, an atmospheric model was developed as part of the Austrian ESO In-Kind contribution. It includes all relevant components, such as scattered moonlight, scattered starlight, zodiacal light, atmospheric thermal radiation and absorption, and non-thermal airglow emission. This paper focuses on atmospheric scattering processes that mostly affect the blue (<0.55&#8201;&#956;m) wavelength regime, and airglow emission lines and continuum that dominate the red (>0.55&#8201;&#956;m) wavelength regime. While the former is mainly investigated by means of radiative transfer models, the intensity and variability of the latter is studied with a sample of 1186 VLT FORS&#8201;1 spectra.

Results. For a set of parameters such as the object altitude angle, Moon-object angular distance, ecliptic latitude, bimonthly period, and solar radio flux, our model predicts atmospheric radiation and transmission at a requested resolution. A comparison of our model with the FORS&#8201;1 spectra and photometric data for the night-sky brightness from the literature, suggest a model accuracy of about 20%. This is a significant improvement with respect to existing predictive atmospheric models for astronomical exposure time calculators.
 
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  ISSN 0004-6361 ISBN Medium  
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  Notes Approved no  
  Call Number IDA @ john @ Serial 274  
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Author Kocifaj, M.; Kómar, L. url  doi
openurl 
  Title A role of aerosol particles in forming urban skyglow and skyglow from distant cities Type Journal Article
  Year 2016 Publication Monthly Notices of the Royal Astronomical Society Abbreviated Journal MNRAS  
  Volume (down) 458 Issue 1 Pages 438-448  
  Keywords Skyglow; scattering; atmospheric effects; artificial light; numerical modeling; GIS-based modeling; light pollution  
  Abstract Aerosol particles may represent the largest uncertainty about skyglow change in many locations under clear sky conditions. This is because aerosols are ubiquitous in the atmosphere and influence the ground-reaching radiation in different ways depending on their concentrations, origins, shapes, sizes, and compositions. Large particles tend to scatter in Fraunhofer diffraction regime, while small particles can be treated in terms of Rayleigh formalism. However, the role of particle microphysics in forming the skyglow still remains poorly quantified. We have shown in this paper that the chemistry is somehow important for backscattering from large particles that otherwise work as efficient attenuators of light pollution if composed of absorbing materials. The contribution of large particles to the urban skyglow diminishes as they become more spherical in shape. The intensity of backscattering from non-absorbing particles is more-or-less linearly decreasing function of particle radius even if number size distribution is inversely proportional to the fourth power of particle radius. This is due to single particle backscattering that generally increases steeply as the particle radius approaches large values. Forward scattering depends on the particle shape but is independent of the material composition, thus allowing for a simplistic analytical model of skyglow from distant cities. The model we have developed is based on mean value theorem for integrals and incorporates the parametrizable Garstang's emission pattern, intensity decay along optical beam path, and near-forward scattering in an atmospheric environment. Such model can be used by modellers and experimentalists for rapid estimation of skyglow from distant light sources.  
  Address ICA, Slovak Academy of Sciences, Dúbravská Road 9, 845 03 Bratislava, Slovak Republic; kocifaj(at)savba.sk  
  Corporate Author Thesis  
  Publisher Oxford Journals Place of Publication Editor  
  Language English Summary Language English Original Title  
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  Call Number IDA @ john @ Serial 1361  
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Author Kocifaj, M.; Solano Lamphar, H.A. url  doi
openurl 
  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 Cinzano, P.; Falchi, F. url  doi
openurl 
  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&#8201;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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  Call Number IDA @ john @ Serial 271  
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Author Crumey, A. url  doi
openurl 
  Title Human Contrast Threshold and Astronomical Visibility. Type Journal Article
  Year 2014 Publication Monthly Notices of the Royal Astronomical Society Abbreviated Journal MNRAS  
  Volume (down) 422 Issue 3 Pages 2600-2619  
  Keywords Vision; visibility; skyglow; sky brightness; modeling  
  Abstract The standard visibility model in light-pollution studies is the formula of Hecht, as used e.g. by Schaefer. However, it is applicable only to point sources and is shown to be of limited accuracy. A new visibility model is presented for uniform achromatic targets of any size against background luminances ranging from zero to full daylight, produced by a systematic procedure applicable to any appropriate data set (e.g. Blackwell's), and based on a simple but previously unrecognized empirical relation between contrast threshold and adaptation luminance. The scotopic luminance correction for variable spectral radiance (colour index) is calculated. For point sources, the model is more accurate than Hecht's formula and is verified using telescopic data collected at Mount Wilson in 1947, enabling the sky brightness at that time to be determined. The result is darker than the calculation by Garstang, implying that light pollution grew more rapidly in subsequent decades than has been supposed. The model is applied to the nebular observations of William Herschel, enabling his visual performance to be quantified. Proposals are made regarding sky quality indicators for public use.  
  Address Department of Humanities, Northumbria University, Newcastle upon Tyne NE1 8ST, UK; andrew.crumey(at)northumbria.ac.uk  
  Corporate Author Thesis  
  Publisher Oxford Journals Place of Publication Editor  
  Language English Summary Language English Original Title  
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  ISSN 0035-8711 ISBN Medium  
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  Notes Approved no  
  Call Number LoNNe @ christopher.kyba @ Serial 536  
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Author Kocifaj, M. url  doi
openurl 
  Title A numerical experiment on light pollution from distant sources: Light pollution from distant sources Type Journal Article
  Year 2011 Publication Monthly Notices of the Royal Astronomical Society Abbreviated Journal MNRAS  
  Volume (down) 415 Issue 4 Pages 3609-3615  
  Keywords scattering; atmospheric effects; light pollution; methods: numerical; skyglow; modeling  
  Abstract To predict the light pollution of the night-time sky realistically over any location or measuring point on the ground presents quite a difficult calculation task. Light pollution of the local atmosphere is caused by stray light, light loss or reflection of artificially illuminated ground objects or surfaces such as streets, advertisement boards or building interiors. Thus it depends on the size, shape, spatial distribution, radiative pattern and spectral characteristics of many neighbouring light sources. The actual state of the atmospheric environment and the orography of the surrounding terrain are also relevant. All of these factors together influence the spectral sky radiance/luminance in a complex manner. Knowledge of the directional behaviour of light pollution is especially important for the correct interpretation of astronomical observations. From a mathematical point of view, the light noise or veil luminance of a specific sky element is given by a superposition of scattered light beams. Theoretical models that simulate light pollution typically take into account all ground-based light sources, thus imposing great requirements on CPU and MEM. As shown in this paper, a contribution of distant sources to the light pollution might be essential under specific conditions of low turbidity and/or Garstang-like radiative patterns. To evaluate the convergence of the theoretical model, numerical experiments are made for different light sources, spectral bands and atmospheric conditions. It is shown that in the worst case the integration limit is approximately 100 km, but it can be significantly shortened for light sources with cosine-like radiative patterns.  
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  Notes Approved no  
  Call Number IDA @ john @ Serial 267  
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Author Kocifaj, M. url  doi
openurl 
  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 (down) 403 Issue 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  
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  Notes Approved no  
  Call Number IDA @ john @ Serial 276  
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Author Xavier Kerola, D. url  doi
openurl 
  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 (down) 365 Issue 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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  ISSN 0035-8711 ISBN Medium  
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  Notes Approved no  
  Call Number IDA @ john @ Serial 278  
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Author Kocifaj, M. url  doi
openurl 
  Title Two-stream approximation for rapid modeling the light pollution levels in local atmosphere Type Journal Article
  Year 2012 Publication Astrophysics and Space Science Abbreviated Journal Astrophys Space Sci  
  Volume (down) 341 Issue 2 Pages 301-307  
  Keywords Light pollution; Atmospheric effects; Methods: numerical; Radiative transfer; Scattering; modeling; two-stream approximation  
  Abstract The two-stream concept is used for modeling the radiative transfer in Earth's atmosphere illuminated by ground-based light sources. The light pollution levels (illuminance and irradiance) are computed for various aerosol microphysical parameters, specifically the asymmetry parameter g A , single scattering albedo ω A , and optical thickness τ A . Two distinct size distributions of Junge's and gamma-type are employed. Rather then being a monotonic function of τ A , the diffuse illuminance/irradiance shows a local minimum at specific τ A, lim independent of size distribution taken into consideration. The existence of local minima has relation to the scattering and attenuation efficiencies both of which have opposite effects. The computational scheme introduced in this paper is advantageous especially if the entire set of calculations needs to be repeated with an aim to simulate diffuse light in various situations and when altering optical states of the atmospheric environment.  
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  ISSN 0004-640X ISBN Medium  
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  Notes Approved no  
  Call Number IDA @ john @ Serial 273  
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Author Cinzano, P.; Falchi, F.; Elvidge, C.D. url  doi
openurl 
  Title Naked-eye star visibility and limiting magnitude mapped from DMSP-OLS satellite data Type Journal Article
  Year 2001 Publication Monthly Notices of the Royal Astronomical Society Abbreviated Journal Monthly Notices of the Royal Astronomical Society  
  Volume (down) 323 Issue 1 Pages 34-46  
  Keywords light at night; remote sensing; GTOPO30; DMSP; light pollution; modeling; mapping  
  Abstract We extend the method introduced by Cinzano et al. (2000a) to map the artificial sky brightness in large territories from DMSP satellite data, in order to map the naked eye star visibility and telescopic limiting magnitudes. For these purposes we take into account the altitude of each land area from GTOPO30 world elevation data, the natural sky brightness in the chosen sky direction, based on Garstang modelling, the eye capability with naked eye or a telescope, based on the Schaefer (1990) and Garstang (2000b) approach, and the stellar extinction in the visual photometric band. For near zenith sky directions we also take into account screening by terrain elevation. Maps of naked eye star visibility and telescopic limiting magnitudes are useful to quantify the capability of the population to perceive our Universe, to evaluate the future evolution, to make cross correlations with statistical parameters and to recognize areas where astronomical observations or popularisation can still acceptably be made. We present, as an application, maps of naked eye star visibility and total sky brightness in V band in Europe at the zenith with a resolution of approximately 1 km.  
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  ISSN 0035-8711 ISBN Medium  
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  Notes Approved no  
  Call Number IDA @ john @ Serial 175  
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