Lu, L., Weng, Q., Xie, Y., Guo, H., & Li, Q. (2019). An assessment of global electric power consumption using the Defense Meteorological Satellite Program-Operational Linescan System nighttime light imagery. Energy, 189, 116351.
Abstract: Industrialization and urbanization have led to a remarkable increase of electric power consumption (EPC) during the past decades. To assess the changing patterns of EPC at the global scale, this study utilized nighttime lights in conjunction with population and built-up datasets to map EPC at 1 km resolution. Firstly, the inter-calibrated nighttime light data were enhanced using the V4.0 Gridded Population Density data and the Global Human Settlement Layer. Secondly, linear models were calibrated to relate EPC to the enhanced nighttime light data; these models were then employed to estimate per-pixel EPC in 2000 and 2013. Finally, the spatiotemporal patterns of EPC between the periods were analyzed at the country, continental, and global scales. The evaluation of the EPC estimation shows a reasonable accuracy at the provincial scale with R2 of 0.8429. Over 30% of the human settlements in Asia, Europe, and North America showed apparent EPC growth. At the national scale, moderate and high EPC growth was observed in 45% of the built-up areas in East Asia. The spatial clustering patterns revealed that EPC decreased in Russia and the Western Europe. This study provides fresh insight into the spatial pattern and variations of global electric power consumption.
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Kocifaj, M., Wallner, S., & Solano-Lamphar, H. A. (2019). An asymptotic formula for skyglow modelling over a large territory. Monthly Notices of the Royal Astronomical Society, 485(2), 2214–2224.
Abstract: An analytical framework to predict skyglow due to distant sources is presented, which can be applied to model sky brightness from the zenith toward the horizon along a vertical plane crossing the hemisphere in the azimuthal position of a light source. Although various powerful algorithms have been developed over the last few decades, the time needed for calculation grows exponentially with increasing size of the modelling domain. This is one of the key issues in skyglow computations, because the numerical accuracy improves only slowly as the modelling domain extends. We treat the problem theoretically, by introducing an analytical formula that is well-suited for light sources located at intermediate and long distances from an observation point and allows tremendous time savings in numerical analyses, while keeping the error at a low level. Field experiments carried out in Eastern Austria provided a unique opportunity to validate the model using real-sky luminance data. The fact that the theoretical model allows the prediction of sky luminance within an acceptable error tolerance is not only in line with the experimental data, but also provides new means of remote characterization of light emissions from artificial sources. The method is particularly attractive for rapid and simple retrieval of the amount of light escaping upwards from the dominant light sources surrounding the observation point. We expect that the method can advance the numerical modelling of skyglow substantially, because it allows real-time computations for very large territories.
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Jørgensen, L. D., Tambo, T., & Xydis, G. (2019). An efficiency evaluation of radar‐based obstruction lights controlling at a wind turbine test site. Wind Energy, 22(4).
Abstract: In this study, an obstruction lights controlling (OLC) system based on a Terma SCANTER 5000 radar has been installed at a test centre for large wind turbines. The objective of this study was to evaluate the efficiency of the OLC system and to improve this efficiency by introducing new technological features. Once the first assessment had been carried out, new software with improved tracking functionalities was installed to the radar. With the new software, a second assessment was made to compare the new performance to the old one. To analyse the tracks, geographic information system (GIS) tools have been used. A new MATLAB script was developed to automate the assessment as well as to gather data on the tracks. These data sets were used to improve the system performance by introducing a radar cross section (RCS)/speed filter. The outcome of the study is a filter that can be implemented on the radar system to improve the efficiency of the system and reduce the time that obstruction lights need to be on for by 62.59%, without compromising the integrity of the system.
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Bailey, L. A., Brigham, R. M., Bohn, S. J., Boyles, J. G., & Smit, B. (2019). An experimental test of the allotonic frequency hypothesis to isolate the effects of light pollution on bat prey selection. Oecologia, 190(2), 367–374.
Abstract: Artificial lights may be altering interactions between bats and moth prey. According to the allotonic frequency hypothesis (AFH), eared moths are generally unavailable as prey for syntonic bats (i.e., bats that use echolocation frequencies between 20 and 50 kHz within the hearing range of eared moths) due to the moths' ability to detect syntonic bat echolocation. Syntonic bats therefore feed mainly on beetles, flies, true bugs, and non-eared moths. The AFH is expected to be violated around lights where eared moths are susceptible to exploitation by syntonic bats because moths' evasive strategies become less effective. The hypothesis has been tested to date almost exclusively in areas with permanent lighting, where the effects of lights on bat diets are confounded with other aspects of human habitat alteration. We undertook diet analysis in areas with short-term, localized artificial lighting to isolate the effects of artificial lighting and determine if syntonic and allotonic bats (i.e., bats that use echolocation frequencies outside the hearing range of eared moths) consumed more moths under conditions of artificial lights than in natural darkness. We found that syntonic bats increased their consumption of moth prey under experimentally lit conditions, likely owing to a reduction in the ability of eared moths to evade the bats. Eared moths may increase in diets of generalist syntonic bats foraging around artificial light sources, as opposed to allotonic species and syntonic species with a more specialized diet.
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Kronauer, R. E., St Hilaire, M. A., Rahman, S. A., Czeisler, C. A., & Klerman, E. B. (2019). An Exploration of the Temporal Dynamics of Circadian Resetting Responses to Short- and Long-Duration Light Exposures: Cross-Species Consistencies and Differences. J Biol Rhythms, 34(5), 497–514.
Abstract: Light is the most effective environmental stimulus for shifting the mammalian circadian pacemaker. Numerous studies have been conducted across multiple species to delineate wavelength, intensity, duration, and timing contributions to the response of the circadian pacemaker to light. Recent studies have revealed a surprising sensitivity of the human circadian pacemaker to short pulses of light. Such responses have challenged photon counting-based theories of the temporal dynamics of the mammalian circadian system to both short- and long-duration light stimuli. Here, we collate published light exposure data from multiple species, including gerbil, hamster, mouse, and human, to investigate these temporal dynamics and explore how the circadian system integrates light information at both short- and long-duration time scales to produce phase shifts. Based on our investigation of these data sets, we propose 3 new interpretations: (1) intensity and duration are independent factors of total phase shift magnitude, (2) the possibility of a linear/log temporal function of light duration that is universal for all intensities for durations less than approximately 12 min, and (3) a potential universal minimum light duration of ~0.7 sec that describes a “dead zone” of light stimulus. We show that these properties appear to be consistent across mammalian species. These interpretations, if confirmed by further experiments, have important practical implications in terms of understanding the underlying physiology and for the design of lighting regimens to reset the mammalian circadian pacemaker.
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