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Cao, X., Hu, Y., Zhu, X., Shi, F., Zhuo, L., & Chen, J. (2019). A simple self-adjusting model for correcting the blooming effects in DMSP-OLS nighttime light images. Remote Sensing of Environment, 224, 401–411.
Abstract: Night-time light (NTL) data from the Defense Meteorological Satellite Program (DMSP) Operation Linescan System (OLS) provide important observations of human activities; however, DMSP-OLS NTL data suffer from problems such as saturation and blooming. This research developed a self-adjusting model (SEAM) to correct blooming effects in DMSP-OLS NTL data based on a spatial response function and without using any ancillary data. By assuming that the pixels adjacent to the background contain no lights (i.e., pseudo light pixels, PLPs), the blooming effect intensity, a parameter in the SEAM model, can be estimated by pixel-based regression using PLPs and their neighboring light sources. SEAM was applied to all of China, and its performance was assessed for twelve cities with different population sizes. The results show that SEAM can largely reduce the blooming effect in the original DMSP-OLS dataset and enhance its quality. The images after blooming effect correction have higher spatial similarity with Suomi National Polar-orbiting Partnership Visible Infrared Imaging Radiometer Suite (VIIRS) images and higher spatial variability than the original DMSP-OLS data. We also found that the average effective blooming distance is approximately 3.5 km in China, which may be amplified if the city is surrounded by water surfaces, and that the blooming effect intensity is positively correlated to atmospheric quality. The effectiveness of the proposed model will improve the capacity of DMSP-OLS images for mapping the urban extent and modeling socioeconomic parameters.
Keywords: Remote Sensing
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Nagare, R., Rea, M. S., Plitnick, B., & Figueiro, M. G. (2019). Effect of White Light Devoid of “Cyan” Spectrum Radiation on Nighttime Melatonin Suppression Over a 1-h Exposure Duration. J Biol Rhythms, 34(2), 195–204.
Abstract: The intrinsically photosensitive retinal ganglion cells are the main conduit of the light signal emanating from the retina to the biological clock located in the suprachiasmatic nuclei of the hypothalamus. Lighting manufacturers are developing white light sources that are devoid of wavelengths around 480 nm (“cyan gap”) to reduce their impact on the circadian system. The present study was designed to investigate whether exposure to a “cyan-gap,” 3000 K white light source, spectrally tuned to reduce radiant power between 475 and 495 nm (reducing stimulation of the melanopsin-containing photoreceptor), would suppress melatonin less than a conventional 3000 K light source. The study's 2 phases employed a within-subjects experimental design involving the same 16 adult participants. In Phase 1, participants were exposed for 1 h to 3 experimental conditions over the course of 3 consecutive weeks: 1) dim light control (<5 lux at the eyes); 2) 800 lux at the eyes of a 3000 K light source; and 3) 800 lux at the eyes of a 3000 K, “cyan-gap” modified (3000 K mod) light source. The same protocol was repeated in Phase 2, but light levels were reduced to 400 lux at the eyes. As hypothesized, there were significant main effects of light level ( F1,12 = 9.1, p < 0.05, etap(2) = 0.43) and exposure duration ( F1,12 = 47.7, p < 0.05, etap(2) = 0.80) but there was no significant main effect of spectrum ( F1,12 = 0.16, p > 0.05, etap(2) = 0.01). There were no significant interactions with spectrum. Contrary to our model predictions, our results showed that short-term exposures (</= 1 h) to “cyan-gap” light sources suppressed melatonin similarly to conventional light sources of the same CCT and photopic illuminance at the eyes.
Keywords: Human Health; melatonin; melatonin suppression; cyan light
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Marinac, C. R., Quante, M., Mariani, S., Weng, J., Redline, S., Cespedes Feliciano, E. M., et al. (2019). Associations Between Timing of Meals, Physical Activity, Light Exposure, and Sleep With Body Mass Index in Free-Living Adults. J Phys Act Health, 16(3), 214–221.
Abstract: BACKGROUND: This study tested if the timing of meals, physical activity, light exposure, and sleep cluster within individuals and are associated with body mass index (BMI) in a sample of free-living adults (N = 125). METHODS: Data were collected between November 2015 and March 2016 at the University of California, San Diego, Children's Hospital of Philadelphia, and Washington University in St Louis. Height and weight were measured, and BMI (kg/m(2)) was calculated. Sleep timing was estimated using actigraphy, and timing of meals, physical activity, and light exposure were self-reported using a smartphone application. General linear models estimated the mean BMI across time categories of behaviors, adjusting for covariates. A latent class analysis was used to identify patterns of timing variables that clustered within individuals and test for associations between identified patterns and BMI. RESULTS: Later exposure to outdoor light was associated with a lower BMI (P trend < .01). The timing of other behaviors was not independently associated with BMI. The latent class analysis identified 2 distinct groups related to behavioral timing, reflecting an “early bird” and “night owl” phenotype. These phenotypes were not associated with BMI (P > .05). CONCLUSION: Timing of exposures to light, meals, sleep, and physical activity were not strongly associated with BMI in this sample.
Keywords: Human Health
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Hu, T., & Huang, X. (2019). A novel locally adaptive method for modeling the spatiotemporal dynamics of global electric power consumption based on DMSP-OLS nighttime stable light data. Applied Energy, 240, 778–792.
Abstract: Timely and reliable estimation of electricity power consumption (EPC) is essential to the rational deployment of electricity power resources. Nighttime stable light (NSL) data from the Defense Meteorological Satellite Program Operational Linescan System (DMSP-OLS) have the potential to model global 1-km gridded EPC. A processing chain to estimate EPC includes: (1) NSL data correction; and (2) regression model between EPC statistics and NSL data. For the global gridded EPC estimation, the current approach is to correct the global NSL image in a uniform manner and establish the linear relationships between NSL and EPC. However, the impacts of local socioeconomic inconsistencies on the NSL correction and model establishment are not fully considered. Therefore, in this paper, we propose a novel locally adaptive method for global EPC estimation. Firstly, we set up two options (with or without the correction) for each local area considering the global NSL image is not saturated everywhere. Secondly, three directions (forward, backward, or average) are alternatives for the inter-annual correction to remove the discontinuity effect of NSL data. Thirdly, four optional models (linear, logarithmic, exponential, or second-order polynomial) are adopted for the EPC estimation of each local area with different socioeconomic dynamic. Finally, the options for each step constitute all candidate processing chains, from which the optimal one is adaptively chosen for each local area based on the coefficient of determination. The results demonstrate that our product outperforms the existing one, at global, continental, and national scales. Particularly, the proportion of countries/districts with a high accuracy (MARE (mean of the absolute relative error) ≤ 10%) increases from 17.8% to 57.8% and the percentage of countries/districts with inaccurate results (MARE > 50%) decreases sharply from 23.0% to 3.7%. This product can enhance the detailed understanding of the spatiotemporal dynamics of global EPC.
Keywords: Remote Sensing
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Viera-Perez, M., Hernandez-Calvento, L., Hesp, P. A., & Santana-Del Pino, A. (2019). Effects of artificial light on flowering of foredune vegetation. Ecology, 100(5), e02678.
Abstract: The impact of ecological light pollution involves alteration of periods of natural light, a fact that has proven effects on ecosystems. Few studies have focused on the impact of this pollution on wild plant species, and none on coastal dune plants. Many coastal dunes and their plants are adjacent to tourist areas, and these might be affected by light pollution. Such is the case of the Natural Reserve Dunas de Maspalomas (Gran Canaria), where some individuals of the plant species Traganum moquinii, located in the El Ingles beach foredune zone, are affected by light pollution. This study examines the effect of light pollution on the flowering process, and by extension the reproductive cycle of these plants. Plants located closer to high artificial illumination sources receive ~2120 hours per year of intense light more than plants located furthest from those artificial lighting sources. Parts of the plants of Traganum moquinii exposed directly to the artificial light show a significant decrease in the production of flowers, compared to the parts in plants in shade, and to the plants more distant from artificial lights. In consequence, plants exposed more directly to artificial light have a lower potential for seed reproduction. The spectrum of artificial light also affects the plants, and light between 600 and 700 nm primarily affects the reproductive cycle of the Traganum moquinii species. The implications for the ecological and geomorphological functioning of the dune system are discussed, because this species plays a decisive role in the formation of foredune zones and nebkhas in arid dune systems.
Keywords: Plants; Coastal management; coastal dunes; Canary Islands; Spain; Europe
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