A multi-value based approach to identify potential dark sky places in mainland China

With the expansion of global population and rapid development of urbanization and lighting technologies, artificial light at night (ALAN) has caused increasing negative impacts on the dark sky observation, which has aroused wide concern on the protection of dark sky in the world. Dark skies have great natural, cultural, aesthetic, and economic values, and construction of dark sky places is an effective strategy to protect dark skies. In this study, a distribution map of dark sky quality is constructed with multi-dimensional values of dark sky, and multiple potential types of dark sky places are identified in mainland China. First, light pollution index, atmospheric transparency index, and clearness index were superposed to create a map for the distribution of dark sky quality. Then, the construction potential of dark sky places was estimated based on the attractiveness and accessibility. Finally, dark sky quality and construction potential of dark sky places were spatially correlated to identify different types of dark sky places. The results demonstrated that high-quality dark skies are mainly distributed in vast stretches of the western regions, which are characterized by large areas and scales and account for about 40.06 % of land area in mainland China. Spatially, we identified a total of 136 potential dark sky sanctuaries and 67 dark sky reserves/parks, as well as 379,335.8 km² regions that are suitable for the construction of dark sky communities or urban night sky places. These findings may lay a foundation for the site selection of different types of dark sky places in countries like China.