RESUMO
The rapid development of cities has brought tremendous pressure to astronomical observation, energy security, and the ecosystem. Automatic monitoring of night sky brightness (NSB) can help us to understand its regional differences and time variations of NSB effectively and to investigate the human and natural factors which lead to these changes. In this paper, the construction of Wuxi City night sky brightness monitoring network (WBMN) in China is presented. In addition to introducing the equipment and the installation of the network, a brief analysis of the data obtained from the stations will also be presented. The impact of human activities on the NSB is illustrated through its changes during the Spring Festival (lunar new year) and non-festival nights, and through a comparison study between NSB data taken from locations of different land usages. It is concluded that, while the reduction in human activities after non-festival midnights or the reduction in moon illumination near the new moon epoch led to darker night skies, brightening of the night skies may be attributed to firework displays during the nights of Spring Festival in 2019. On the other hand, the absence of firework during the Spring Festival in 2020 may explain the darker night skies. Finally, there is an evidence that the urban developments in Wuxi are degrading night sky quality.
RESUMO
Results of the first comprehensive light pollution survey in Hong Kong are presented. The night-sky brightness was measured and monitored around the city using a portable light-sensing device called the Sky Quality Meter over a 15-month period beginning in March 2008. A total of 1,957 data sets were taken at 199 distinct locations, including urban and rural sites covering all 18 Administrative Districts of Hong Kong. The survey shows that the environmental light pollution problem in Hong Kong is severe-the urban night skies (sky brightness at 15.0 mag arcsec(- 2)) are on average ~ 100 times brighter than at the darkest rural sites (20.1 mag arcsec(- 2)), indicating that the high lighting densities in the densely populated residential and commercial areas lead to light pollution. In the worst polluted urban location studied, the night-sky at 13.2 mag arcsec(- 2) can be over 500 times brighter than the darkest sites in Hong Kong. The observed night-sky brightness is found to be affected by human factors such as land utilization and population density of the observation sites, together with meteorological and/or environmental factors. Moreover, earlier night skies (at 9:30 p.m. local time) are generally brighter than later time (at 11:30 p.m.), which can be attributed to some public and commercial lightings being turned off later at night. On the other hand, no concrete relationship between the observed sky brightness and air pollutant concentrations could be established with the limited survey sampling. Results from this survey will serve as an important database for the public to assess whether new rules and regulations are necessary to control the use of outdoor lightings in Hong Kong.
