Manuel García-Gil | Searcharxiv

arXiv2024

Assessing light pollution in vast areas: zenith sky brightness maps of Catalonia

Zenith sky brightness maps in the V and B bands of the region of Catalonia are presented in this paper. For creating them we have used the light pollution numerical model Illumina v2. The maps have a sampling of 5x5 km for the whole region with an improved resolution of 1x1 km for one of the provinces within Catalonia, Tarragona. Before creating the final maps, the methodology was tested successfully by comparing the computed values to measurements in nineteen different locations spread out throughout the territory. The resulting maps have been compared to the zenith sky brightness world atlas and also to Sky Quality Meter (SQM) dynamic measurements. When comparing to measurements we found small differences mainly due to mismatching in the location of the points studied, and also due to differences in the natural sky brightness and atmospheric content. In the comparison to the world atlas some differences were expected as we are taking into account the blocking effect of topography and obstacles, and also due to a more precise light sources characterization. The results of this work confirm the conclusion found in other studies that the minimum sampling for studying sky brightness fine details is of 1x1 km. However, a sampling of 5x5 km is interesting when studying general trends, mainly for vast areas, due to the reduction of the time required to create the maps.

astro-ph.IM↗

arXiv2018

Light pollution offshore: zenithal sky glow measurements in the Mediterranean coastal waters

Light pollution is a worldwide phenomenon whose consequences for the natural environment and the human health are being intensively studied nowadays. Most published studies address issues related to light pollution inland. Coastal waters, however, are spaces of high environmental interest, due to their biodiversity richness and their economical significance. The elevated population density in coastal regions is accompanied by correspondingly large emissions of artificial light at night, whose role as an environmental stressor is increasingly being recognized. (...) At the same time, the marine surface environment provides a stage free from obstacles for measuring the dependence of the skyglow on the distance to the light polluting sources, and validating (or rejecting) atmospheric light propagation models. In this work we present a proof-of-concept of a gimbal measurement system that can be used for zenithal skyglow measurements on board both small boats and large vessels under actual navigation conditions. We report the results obtained in the summer of 2016 along two measurement routes in the Mediterranean waters offshore Barcelona, travelling 9 and 31.7 km away from the coast. The atmospheric conditions in both routes were different from the ones assumed for the calculation of recently published models of the anthropogenic sky brightness. They were closer in the first route, whose results approach better the theoretical predictions. The results obtained in the second route, conducted under a clearer atmosphere, showed systematic differences that can be traced back to two expected phenomena, which are a consequence of the smaller aerosol content: the reduction of the anthropogenic sky glow at short distances from the sources, and the slower decay rate of brightness with distance, which gives rise to a relative excess of brightness at large distances from the coastline.

astro-ph.IM↗