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Wallner, S., & Kocifaj, M. (2019). Impacts of surface albedo variations on the night sky brightness – A numerical and experimental analysis. Journal of Quantitative Spectroscopy and Radiative Transfer, in press, in press.
Abstract: The aim of this paper is to analyze surface albedo impacts on artificial night sky brightness at zenith. The way in which these parameters correlate with each other is analyzed numerically and then experimentally by Sky Quality Meters (SQMs) in the city of Linz, Austria between 2016 and 2018. Three SQMs are located in city areas that differ in ground type, while other two are installed outside but near the city. To eliminate systematic errors of different SQMs or a missing inter-calibration of all devices, we examine relative change in zenithal brightness instead of its absolute values. However, the ground albedo not only depends on the ground type, but also shows seasonal variation most often driven by vegetation and environmental change. To understand these changes, we use SkyGlow simulator to perform numerical experiments on four different albedo models. The results have proven that seasonal variations are clearly visible as green city parts become darker around autumn and ratios to urban located SQMs increase. We show that there is a major difference in simulation results if either conducting city parts with various surface albedos or using only one averaged value over the whole city. The latter produces worse fit to the observed SQM data, implying that a use of various surface albedos is a need when modelling zenithal brightness in artificially lit areas of a city or town. Also, the seasonal changes of surface albedo cannot be neglected and the parameter itself must be included in the modelling tools.
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Li, H., Wu, M., Tian, D., Wu, L., & Niu, Z. (2019). Monitoring and analysis of the expansion of the Ajmr Port, Davao City, Philippines using multi-source remote sensing data. PeerJ, 7, e7512.
Abstract: Ports have been built or expanded in a number of countries to cater to increasing maritime trade in the 21st century. Port expansion is associated with economic and environmental impacts on the local and regional scales, and these impacts can be studied using remote sensing. The present study presents new results from multi-source remote sensing monitoring of the Ajmr Port expansion. An analysis of land use and vegetation coverage at the port is used to monitor the impact of port construction on the local ecology, while changes in roads, buildings, and lights are used to monitor the economic impact. The results show that: (1) After nine years of expansion, the port area has gradually expanded from the central to the southern coastal area, with an increase of 21.68 hectares during the expansion period. After the expansion, the area of builidings and construction in the study area increased significantly, while the area of water and green areas decreased significantly, indicating that the port construction changed the land use structure of the area. (2) From the perspective of vegetation coverage, the vegetation coverage within 5 km from the port is in good condition. After 9 years, the vegetation coverage in the region between 0.6 and 1 increased from 43.71% to 44.25%, reflecting the higher overall greening level in the region. (3) By analyzing the increase in roads and buildings, it can be seen that the port's comprehensive transportation capacity has improved, the population of the region has increased significantly. As the scale of construction has been continuously expanded , the prosperity as increased. (4) By analyzing the changes in the light index, the light data from the northeast to the southwest in the region is very obvious, and it is clearly located along the coast, indicating that the economic development of the coastal zone is faster than other regions, and the coastal region has promoted the development of the inland region.
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Shlesinger, T., & Loya, Y. (2019). Breakdown in spawning synchrony: A silent threat to coral persistence. Science, 365(6457), 1002–1007.
Abstract: The impacts of human and natural disturbances on coral reefs are typically quantified through visible damage (e.g., reduced coral coverage as a result of bleaching events), but changes in environmental conditions may also cause damage in less visible ways. Despite the current paradigm, which suggests consistent, highly synchronized spawning events, corals that reproduce by broadcast spawning are particularly vulnerable because their reproductive phenology is governed by environmental cues. Here, we quantify coral spawning intensity during four annual reproductive seasons, alongside laboratory analyses at the polyp, colony, and population levels, and we demonstrate that, compared with historical data, several species from the Red Sea have lost their reproductive synchrony. Ultimately, such a synchrony breakdown reduces the probability of successful fertilization, leading to a dearth of new recruits, which may drive aging populations to extinction.
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Li, S., Cheng, L., Liu, X., Mao, J., Wu, J., & Li, M. (2019). City type-oriented modeling electric power consumption in China using NPP-VIIRS nighttime stable light data. Energy, in press.
Abstract: Accelerating urbanization has created tremendous pressure on the global environment and energy supply, making accurate estimates of energy use of great importance. Most current models for estimating electric power consumption (EPC) from nighttime light (NTL) imagery are oversimplified, ignoring influential social and economic factors. Here we propose first classifying cities by economic focus and then separately estimating each category’s EPC using NTL data. We tested this approach using statistical employment data for 198 Chinese cities, 2015 NTL data from the Visible Infrared Imaging Radiometer Suite (VIIRS), and annual electricity consumption statistics. We used cluster analysis of employment by sector to divide the cities into three types (industrial, service, and technology and education), then established a linear regression model for each city's NTL and EPC. Compared with the estimation results before city classification (R2: 0.785), the R2 of the separately modeled service cities and technology and education cities increased to 0.866 and 0.830, respectively. However, the results for industrial cities were less consistent due to their more complex energy consumption structure. In general, using classification before modeling helps reflect factors affecting the relationship between EPC and NTL, making the estimation process more reasonable and improving the accuracy of the results.
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Long, X., Tie, X., Zhou, J., Dai, W., Li, X., Feng, T., et al. (2019). Impact of the Green Light Program on haze in the North China Plain, China. Atmos. Chem. Phys., 19(17), 11185–11197.
Abstract: As the world's largest developing country, China has undergone ever-increasing demand for electricity during the past few decades. In 1996, China launched the Green Light Program (GLP), which became a national energy conservation activity for saving lighting electricity as well as an effective reduction of the coal consumption for power generation. Despite the great success of the GLP, its effects on haze have not been investigated and well understood. This study focused on assessing the potential coal saving induced by the improvement of luminous efficacy, the core of the GLP, and on estimating the consequent effects on the haze in the North China Plain (NCP), where a large number of power plants are located and are often engulfed by severe haze. The estimated potential coal saving induced by the GLP can reach a massive value of 120–323 million tons, accounting for 6.7 %–18.0 % of the total coal consumption for thermal power generation in China. There was a massive potential emission reduction of air pollutants from thermal power generation in the NCP, which was estimated to be 20.0–53.8 Gg for NOx and 6.9–18.7 Gg for SO2 in December 2015. The potential emission reduction induced by the GLP plays important roles in the haze formation, because the NOx and SO2 are important precursors for the formation of particles. To assess the impact of the GLP on haze, sensitivity studies were conducted by applying a regional chemical–dynamical model (WRF-CHEM). The model results suggest that in the case of lower-limit emission reduction, the PM2.5 concentration decreased by 2–5 µg m−3 in large areas of the NCP. In the case of upper-limit emission reduction, there was much more remarkable decrease in PM2.5 concentration (4–10 µg m−3). This study is a good example to illustrate that scientific innovation can induce important benefits for environment issues such as haze.
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