50 research outputs found
Night sky brightness at sites from DMSP-OLS satellite measurements
We apply the sky brightness modelling technique introduced and developed by
Roy Garstang to high-resolution DMSP-OLS satellite measurements of upward
artificial light flux and to GTOPO30 digital elevation data in order to predict
the brightness distribution of the night sky at a given site in the primary
astronomical photometric bands for a range of atmospheric aerosol contents.
This method, based on global data and accounting for elevation, Earth curvature
and mountain screening, allows the evaluation of sky glow conditions over the
entire sky for any site in the World, to evaluate its evolution, to disentangle
the contribution of individual sources in the surrounding territory, and to
identify main contributing sources. Sky brightness, naked eye stellar
visibility and telescope limiting magnitude are produced as 3-dimensional
arrays whose axes are the position on the sky and the atmospheric clarity. We
compared our results to available measurements.Comment: 14 pages, 12 figures, accepted for publication in MNRAS, 17 june 200
Cloud Coverage Acts as an Amplifier for Ecological Light Pollution in Urban Ecosystems
The diurnal cycle of light and dark is one of the strongest environmental factors for life on Earth. Many species in both terrestrial and aquatic ecosystems use the level of ambient light to regulate their metabolism, growth, and behavior. The sky glow caused by artificial lighting from urban areas disrupts this natural cycle, and has been shown to impact the behavior of organisms, even many kilometers away from the light sources. It could be hypothesized that factors that increase the luminance of the sky amplify the degree of this “ecological light pollution”. We show that cloud coverage dramatically amplifies the sky luminance, by a factor of 10.1 for one location inside of Berlin and by a factor of 2.8 at 32 km from the city center. We also show that inside of the city overcast nights are brighter than clear rural moonlit nights, by a factor of 4.1. These results have important implications for choronobiological and chronoecological studies in urban areas, where this amplification effect has previously not been considered