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Author Kocifaj, M.
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 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.
Address
Corporate Author Thesis
Publisher Place of Publication Editor (up)
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0004-640X ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number IDA @ john @ Serial 273
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Author Noll, S.; Kausch, W.; Barden, M.; Jones, A.M.; Szyszka, C.; Kimeswenger, S.; Vinther, J.
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 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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Publisher Place of Publication Editor (up)
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0004-6361 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number IDA @ john @ Serial 274
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Author Elvidge, C.D.; Keith, D.M.; Tuttle, B.T.; Baugh, K.E.
Title Spectral identification of lighting type and character Type Journal Article
Year 2010 Publication Sensors (Basel, Switzerland) Abbreviated Journal Sensors (Basel)
Volume 10 Issue 4 Pages 3961-3988
Keywords Led; Nightsat; lighting efficiency; lighting types; nighttime lights; photopic band
Abstract We investigated the optimal spectral bands for the identification of lighting types and the estimation of four major indices used to measure the efficiency or character of lighting. To accomplish these objectives we collected high-resolution emission spectra (350 to 2,500 nm) for forty-three different lamps, encompassing nine of the major types of lamps used worldwide. The narrow band emission spectra were used to simulate radiances in eight spectral bands including the human eye photoreceptor bands (photopic, scotopic, and “meltopic”) plus five spectral bands in the visible and near-infrared modeled on bands flown on the Landsat Thematic Mapper (TM). The high-resolution continuous spectra are superior to the broad band combinations for the identification of lighting type and are the standard for calculation of Luminous Efficacy of Radiation (LER), Correlated Color Temperature (CCT) and Color Rendering Index (CRI). Given the high cost that would be associated with building and flying a hyperspectral sensor with detection limits low enough to observe nighttime lights we conclude that it would be more feasible to fly an instrument with a limited number of broad spectral bands in the visible to near infrared. The best set of broad spectral bands among those tested is blue, green, red and NIR bands modeled on the band set flown on the Landsat Thematic Mapper. This set provides low errors on the identification of lighting types and reasonable estimates of LER and CCT when compared to the other broad band set tested. None of the broad band sets tested could make reasonable estimates of Luminous Efficacy (LE) or CRI. The photopic band proved useful for the estimation of LER. However, the three photoreceptor bands performed poorly in the identification of lighting types when compared to the bands modeled on the Landsat Thematic Mapper. Our conclusion is that it is feasible to identify lighting type and make reasonable estimates of LER and CCT using four or more spectral bands with minimal spectral overlap spanning the 0.4 to 1.0 um region.
Address Earth Observation Group, Solar and Terrestrial Division, NOAA National Geophysical Data Center, 325 Broadway, Boulder, CO 80305, USA. chris.elvidge@noaa.gov
Corporate Author Thesis
Publisher Place of Publication Editor (up)
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1424-8220 ISBN Medium
Area Expedition Conference
Notes PMID:22319336; PMCID:PMC3274255 Approved no
Call Number IDA @ john @ Serial 275
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Author Kocifaj, M.
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 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.
Address
Corporate Author Thesis
Publisher Place of Publication Editor (up)
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0035-8711 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number IDA @ john @ Serial 276
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Author Kocifaj, M.
Title Light-pollution model for cloudy and cloudless night skies with ground-based light sources Type Journal Article
Year 2007 Publication Applied Optics Abbreviated Journal Appl. Opt.
Volume 46 Issue 15 Pages 3013
Keywords light pollution; modeling
Abstract The scalable theoretical model of light pollution for ground sources is presented. The model is successfully employed for simulation of angular behavior of the spectral and integral sky radiance and&#8725;or luminance during nighttime. There is no restriction on the number of ground-based light sources or on the spatial distribution of these sources in the vicinity of the measuring point (i.e., both distances and azimuth angles of the light sources are configurable). The model is applicable for real finite-dimensional surface sources with defined spectral and angular radiating properties contrary to frequently used point-source approximations. The influence of the atmosphere on the transmitted radiation is formulated in terms of aerosol and molecular optical properties. Altitude and spectral reflectance of a cloud layer are the main factors introduced for simulation of cloudy and&#8725;or overcast conditions. The derived equations are translated into numerically fast code, and it is possible to repeat the entire set of calculations in real time. The parametric character of the model enables its efficient usage by illuminating engineers and&#8725;or astronomers in the study of various light-pollution situations. Some examples of numerical runs in the form of graphical results are presented.
Address
Corporate Author Thesis
Publisher Place of Publication Editor (up)
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0003-6935 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number IDA @ john @ Serial 277
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