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| Author |
Kocifaj, M.; Solano Lamphar, H.A. |
| Title |
Quantitative analysis of night skyglow amplification under cloudy conditions |
Type  |
Journal Article |
| Year |
2014 |
Publication |
Monthly Notices of the Royal Astronomical Society |
Abbreviated Journal |
Monthly Notices of the Royal Astronomical Society |
| Volume |
443 |
Issue |
4 |
Pages |
3665-3674 |
| Keywords |
Skyglow; radiative transfer; scattering; atmospheric effects; light pollution; methods: numerical |
| Abstract |
The radiance produced by artificial light is a major source of nighttime over-illumination. It can, however, be treated experimentally using ground-based and satellite data. These two types of data complement each other and together have a high information content. For instance, the satellite data enable upward light emissions to be normalized, and this in turn allows skyglow levels at the ground to be modelled under cloudy or overcast conditions. Excessive night lighting imposes an unacceptable burden on nature, humans and professional astronomy. For this reason, there is a pressing need to determine the total amount of downwelling diffuse radiation. Undoubtedly, cloudy periods can cause a significant increase in skyglow as a result of amplification owing to diffuse reflection from clouds. While it is recognized that the amplification factor (AF) varies with cloud cover, the effects of different types of clouds, of atmospheric turbidity and of the geometrical relationships between the positions of an individual observer, the cloud layer, and the light source are in general poorly known. In this paper the AF is quantitatively analysed considering different aerosol optical depths (AODs), urban layout sizes and cloud types with specific albedos and altitudes. The computational results show that the AF peaks near the edges of a city rather than at its centre. In addition, the AF appears to be a decreasing function of AOD, which is particularly important when modelling the skyglow in regions with apparent temporal or seasonal variability of atmospheric turbidity. The findings in this paper will be useful to those designing engineering applications or modelling light pollution, as well as to astronomers and environmental scientists who aim to predict the amplification of skyglow caused by clouds. In addition, the semi-analytical formulae can be used to estimate the AF levels, especially in densely populated metropolitan regions for which detailed computations may be CPU-intensive. These new results are of theoretical and experimental significance as they will motivate experimentalists to collect data from various regions to build an overall picture of the AF, and will encourage modellers to test the consistency with theoretical predictions. |
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0035-8711 |
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LoNNe @ christopher.kyba @ |
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538 |
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| Author |
Duriscoe, D.M. |
| Title |
Measuring Anthropogenic Sky Glow Using a Natural Sky Brightness Model. |
Type |
Journal Article |
| Year |
2013 |
Publication |
Publications of the Astronomical Society of the Pacific |
Abbreviated Journal |
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| Volume |
125 |
Issue |
933 |
Pages |
1370-1382 |
| Keywords |
Skyglow |
| Abstract |
Anthropogenic sky glow (a result of light pollution) combines with the natural background brightness of the night sky when viewed by an observer on the earth’s surface. In order to measure the anthropogenic component accurately, the natural component must be identified and subtracted. A model of the moonless natural sky brightness in the V-band was constructed from existing data on the Zodiacal Light, an airglow model based on the van Rhijn function, and a model of integrated starlight (including diffuse galactic light) constructed from images made with the same equipment used for sky brightness observations. The model also incorporates effective extinction by the atmosphere and is improved at high zenith angles (>80°) by the addition of atmospheric diffuse light. The model may be projected onto local horizon coordinates for a given observation at a resolution of 0.05° over the hemisphere of the sky, allowing it to be accurately registered with data images obtained from any site. Zodiacal Light and integrated starlight models compare favorably with observations from remote dark sky sites, matching within ± 8 nL over 95% of the sky. The natural airglow may be only approximately modeled, errors of up to ± 25 nL are seen when the airglow is rapidly changing or has considerable character (banding); ± 8 nL precision may be expected under favorable conditions. When subtracted from all-sky brightness data images, the model significantly improves estimates of sky glow from anthropogenic sources, especially at sites that experience slight to moderate light pollution. |
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LoNNe @ christopher.kyba @ |
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539 |
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Myers, L.; Christian, K.; Kirchner, R. |
| Title |
Flowering responses of 48 lines of oilseed rape (Brassica spp.) to vernalization and daylength |
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Journal Article |
| Year |
1982 |
Publication |
Australian Journal of Agricultural Research |
Abbreviated Journal |
Aust. J. Agric. Res. |
| Volume |
33 |
Issue |
6 |
Pages |
927 |
| Keywords |
Plants |
| Abstract |
Forty-eight lines of Brassica spp, of diverse origins were grown in the glasshouse either under natural daylengths or daylengths extended to 16 h by artificial illumination. Plants were either unvernalized or had been subjected to 6 weeks at 8¦C day and 6¦C night temperatures as seedlings. Lines could be classified into two major groups, according to whether or not vernalization or long photoperiods were essential for 50% flowering within 21 weeks. In six lines, both vernalization and long days were essential for prompt flowering, while only five lines did not respond to either treatment. Strong interactions between lines and treatments were found in the number of leaves and subtended buds at flowering. The results show that a wide range of responses is obtainable from material currently available, offering considerabk, scope for adaptation to different environments. |
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0004-9409 |
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IDA @ intern @ |
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2369 |
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Aubé, M.; Franchomme-Fossé, L.; Robert-Staehler, P.; Houle, V. |
| Title |
Light pollution modeling and detection in a heterogeneous environment: toward a night time aerosol optical depth retrieval method. |
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Journal Article |
| Year |
2005 |
Publication |
Proceedings of SPIE 2005 -- Volume 5890, San Diego, California, USA. |
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5890 |
Issue |
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Pages |
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| Keywords |
Skyglow; aerosol optical depth; remote sensing; light pollution; artificial skyglow |
| Abstract |
Tracking the Aerosol Optical Depth (AOD) is of particular importance in monitoring aerosol contributions to global radiative forcing. Until now, the two standard techniques used for retrieving AOD were; (i) sun photometry, and (ii) satellite based approaches, such as based DDV (Dense Dark Vegetation) inversion algorithms. These methods are only available for use during daylight time since they are based on direct or indirect observation of sunlight. Few attempts have been made to measure AOD behaviour at night. One such method uses spectrally calibrated stars as reference targets but the number of available stars is limited. This is especially true for urban sites where artificial lighting hides most of these stars. In this research, we attempt to provide an alternate method, one which exploits artificial sky glow or light pollution. This methodology links a 3D light pollution model with in situ light pollution measurements. The basic idea is to adjust an AOD value into the model in order to fit measured light pollution. This method requires an accurate model that includes spatial heterogeneity in lighting angular geometry, in lighting spectral dependence, in ground spectral reflectance and in topography. This model, named ILLUMINA, computes 1st and 2nd order molecular and aerosol scattering, as well as aerosol absorption. These model features represent major improvements to previous light pollution models. Therefore, new possibilities for light pollution studies will arise, many of which are of particular interest to the astronomical community. In this paper we will present a first sensitive study applied to the ILLUMINA model. |
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LoNNe @ kagoburian @ |
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554 |
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Albers, S.; Duriscoe, D.M. |
| Title |
Modeling light pollution from population data and implications for National Park Service lands. |
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Journal Article |
| Year |
2001 |
Publication |
George Wright Forum |
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18 |
Issue |
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56-68 |
| Keywords |
Skyglow |
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LoNNe @ kagoburian @ |
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