Peculiarities of the environmental light pollution in Chernivtsi Region

Introduction. Every year industrial development and economic growth make light pollution worsen on a global scale. It is a well-known fact that artificial outdoor lighting causes destruction of wildlife habitat, impacts circadian rhythms of all living beings, disrupts animal behavior and leads to medical disorders of humans. Over the last decade scientists switched their focus from artificial sky glow over large cities to light pollution of rural landscapes, protected areas and roadways. The purpose of this paper consists in assessing night-time light emissions over Chernivtsi Region as well as over city of Chernivtsi using satellite measurements. Methods. Measurements of night-time light emissions were obtained with the help of GIS web application Radiance Light Trends and the light trends analysis tool. The application allows examination of changes in light pollution across selected areas since 1992 and performs time-series analysis with fitting an exponential curve into the data set. Results. The trend in light emissions observed by satellites for Chernivtsi Region indicated brightening at the rate of 2.45 % per year from 1992 to 2014, and 2.93 % per year from 2014 to 2021. The marked increase in the intensity of atmospheric light pollution over Chernivtsi Region is largely attributable to urban expansion of district centers, national & international routes and resort complexes. At the same time, the spatial pattern of the light environment over city of Chernivtsi indicated a nearly constant level of aggregate annual light radiance for the last 8 years. A large irregularly shaped "light spot" was detected on the territory of the Prut-Siret interfluve. It crosses the region from the northwest to the southeast and covers the regional center with its suburbs and the national highway H-10. The night light radiance constitutes 47.49∙10-9 mW/cm2 sr in the center of the spot and more than 1∙10-9 mW/cm2 sr at its edges. The highest level of light pollution in Chernivtsi Region was registered in January, and the lowest – in March. Night-time light emission over two most illuminated highways remains relatively constant regardless of the season. Conclusion. The study highlights that despite low population and low economic activity, rural landscapes demonstrate a trend towards increasing brightness of the night sky. The findings provide a quantitative reference for light pollution management in the region and for further research in the area.