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Jechow, A.; Ribas, S.J.; Domingo, R.C.; Hölker, F.; Kolláth, Z.; Kyba, C.C.M. |
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Title |
Tracking the dynamics of skyglow with differential photometry using a digital camera with fisheye lens |
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Journal Article |
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Year |
2018 |
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Journal of Quantitative Spectroscopy and Radiative Transfer |
Abbreviated Journal |
Journal of Quantitative Spectroscopy and Radiative Transfer |
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209 |
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212-223 |
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Keywords |
Skyglow; Instrumentation |
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Abstract |
rtificial skyglow is dynamic due to changing atmospheric conditions and the switching on and off of artificial lights throughout the night. Street lights as well as the ornamental illumination of historical sites and buildings are sometimes switched off at a certain time to save energy. Ornamental lights in particular are often directed upwards, and can therefore have a major contribution towards brightening of the night sky. Here we use differential photometry to investigate the change in night sky brightness and illuminance during an automated regular switch-off of ornamental light in the town of Balaguer and an organized switch-off of all public lights in the village of Àger, both near Montsec Astronomical Park in Spain. The sites were observed during two nights with clear and cloudy conditions using a DSLR camera and a fisheye lens. A time series of images makes it possible to track changes in lighting conditions and sky brightness simultaneously. During the clear night, the ornamental lights in Balaguer contribute over 20% of the skyglow at zenith at the observational site. Furthermore, we are able to track very small changes in the ground illuminance on a cloudy night near Àger. |
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0022-4073 |
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LoNNe @ kyba @ |
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1807 |
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Lopes, A.C.C.; Villacorta-Correa, M.A.; Carvalho, T.B. |
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Title |
Lower light intensity reduces larval aggression in matrinxã, Brycon amazonicus |
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Journal Article |
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2018 |
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Behavioural Processes |
Abbreviated Journal |
Behavioural Processes |
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151 |
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62-66 |
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Animals |
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Brycon amazonicus shows a high frequency of aggressive behavior, which can be a limiting factor in intensive farming systems. Environmental changes can modulate the social interactions of fish and reduce aggression during the different stages of production. Groups of three larvae at 12 h after hatching (HAH) were subjected to different levels of light intensity: low (17 ± 3 lx), intermediate (204 ± 12.17 lx) and high (1,613.33 ± 499.03 lx), with eight replicates for each level. The lower light intensity reduced the frequency of aggressive interactions and locomotor activity exhibited by the animals. Based on these results, light intensity modulates aggression in B. amazonicus larvae. Manipulation of this factor could improve the social conditions of this species during farming and contribute to the development of new production technologies. |
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0376-6357 |
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LoNNe @ kyba @ |
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1810 |
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Manfrin, A.; Lehmann, D.; van Grunsven, R.H.A.; Larsen, S.; Syväranta, J.; Wharton, G.; Voigt, C.C.; Monaghan, M.T.; Hölker, F. |
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Dietary changes in predators and scavengers in a nocturnally illuminated riparian ecosystem |
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Journal Article |
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2018 |
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Oikos |
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Oikos |
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127 |
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7 |
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960-969 |
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Ecology; Animals |
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Aquatic and terrestrial ecosystems are linked by fluxes of carbon and nutrients in riparian areas. Processes that alter these fluxes may therefore change the diet and composition of consumer communities. We used stable carbon isotope (δ13C) analyses to test whether the increased abundance of aquatic prey observed in a previous study led to a dietary shift in riparian consumers in areas illuminated by artificial light at night (ALAN). We measured the contribution of aquatic-derived carbon to diets in riparian arthropods in experimentally lit and unlit sites along an agricultural drainage ditch in northern Germany. The δ13C signature of the spider Pachygnatha clercki (Tetragnathidae) was 0.7‰ lower in the ALAN-illuminated site in summer, indicating a greater assimilation of aquatic prey. Bayesian mixing models also supported higher intake of aquatic prey under ALAN in summer (34% versus 21%). In contrast, isotopic signatures for P. clercki (0.3‰) and Pardosa prativaga (0.7‰) indicated a preference for terrestrial prey in the illuminated site in summer. Terrestrial prey intake increased in spring for P. clercki under ALAN (from 70% to 74%) and in spring and autumn for P. prativaga (from 68% to 77% and from 67% to 72%) and Opiliones (from 68% to 72%; 68% to 75%). This was despite most of the available prey (up to 80%) being aquatic in origin. We conclude that ALAN changed the diet of riparian secondary consumers by increasing the density of both aquatic and terrestrial prey. Dietary changes were species- and season-specific, indicating that the effects of ALAN may interact with phenology and feeding strategy. Because streetlights can occur in high density near freshwaters, ALAN may have widespread effects on aquatic-terrestrial ecosystem linkages. |
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0030-1299 |
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LoNNe @ kyba @ |
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1811 |
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Fu, D.; Xia, X.; Duan, M.; Zhang, X.; Li, X.; Wang, J.; Liu, J. |
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Mapping nighttime PM 2.5 from VIIRS DNB using a linear mixed-effect model |
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2018 |
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Atmospheric Environment |
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Atmospheric Environment |
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178 |
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214-222 |
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Remote Sensing |
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Estimation of particulate matter with aerodynamic diameter less than 2.5 μm (PM2.5) from daytime satellite aerosol products is widely reported in the literature; however, remote sensing of nighttime surface PM2.5 from space is very limited. PM2.5 shows a distinct diurnal cycle and PM2.5 concentration at 1:00 local standard time (LST) has a linear correlation coefficient (R) of 0.80 with daily-mean PM2.5. Therefore, estimation of nighttime PM2.5 is required toward an improved understanding of temporal variation of PM2.5 and its effects on air quality. Using data from the Day/Night Band (DNB) of the Visible Infrared Imaging Radiometer Suite (VIIRS) and hourly PM2.5 data at 35 stations in Beijing, a mixed-effect model is developed here to estimate nighttime PM2.5 from nighttime light radiance measurements based on the assumption that the DNB-PM2.5 relationship is constant spatially but varies temporally. Cross-validation showed that the model developed using all stations predict daily PM2.5 with mean determination coefficient (R2) of 0.87 ±± 0.12, 0.83 ±0.10±0.10, 0.87 ±± 0.09, 0.83 ±± 0.10 in spring, summer, autumn and winter. Further analysis showed that the best model performance was achieved in urban stations with average cross-validation R2 of 0.92. In rural stations, DNB light signal is weak and was likely smeared by lunar illuminance that resulted in relatively poor estimation of PM2.5. The fixed and random parameters of the mixed-effect model in urban stations differed from those in suburban stations, which indicated that the assumption of the mixed-effect model should be carefully evaluated when used at a regional scale. |
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1352-2310 |
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LoNNe @ kyba @ |
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1814 |
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Nagare, R.; Plitnick, B.; Figueiro, M. |
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Effect of exposure duration and light spectra on nighttime melatonin suppression in adolescents and adults |
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2018 |
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Lighting Research & Technology |
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Lighting Research & Technology |
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51 |
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4 |
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530-543 |
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Human Health |
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This study investigated how light exposure duration affects melatonin suppression, a well-established marker of circadian phase, and whether adolescents (13–18 years) are more sensitive to short-wavelength (blue) light than adults (32–51 years). Twenty-four participants (12 adolescents, 12 adults) were exposed to three lighting conditions during successive 4-h study nights that were separated by at least one week. In addition to a dim light (<5 lux) control, participants were exposed to two light spectra (warm (2700 K) and cool (5600 K)) delivering a circadian stimulus of 0.25 at eye level. Repeated measures analysis of variance revealed a significant main effect of exposure duration, indicating that a longer duration exposure suppressed melatonin to a greater degree. The analysis further revealed a significant main effect of spectrum and a significant interaction between spectrum and participant age. For the adolescents, but not the adults, melatonin suppression was significantly greater after exposure to the 5600 K intervention (43%) compared to the 2700 K intervention (29%), suggesting an increased sensitivity to short-wavelength radiation. These results will be used to extend the model of human circadian phototransduction to incorporate factors such as exposure duration and participant age to better predict effective circadian stimulus. |
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1477-1535 |
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GFZ @ kyba @ |
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1821 |
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