In recent years, the number of artificial light sources has tremendously increased with the development of lighting technology and the economy. Nighttime light pollution has been an increasing environmental problem, resulting in negative impacts on human health and the ecological environment. Detailed knowledge of light pollution is important for the planning and management of urban lighting. In this study, light pollution in Nanjing, China was monitored and analyzed using field observations and a 130-m resolution Luojia 1-01 nighttime light imagery. Combined with in situ observations and satellite imagery, a variety of empirical models were established for estimating ambient illuminance at night. Cross-validation was employed to assess the performance of these models, indicating that the third-degree polynomials model had the best performance (MAE = 5.06 lx, R2 = 0.81). The developed third-degree polynomial model was then applied to the Luojia 1-01 image to map the nighttime illuminance in Nanjing. The nighttime illuminance depicted the spatial pattern of the light environment over Nanjing and also indicated some heavily light-polluted areas. Some lit areas were residential areas, whose high brightness had negative effects on residents and need particular attention. This study provides a quantitative and objective reference for the light pollution management in Nanjing, and also a reference for light pollution survey in other regions.
Industrial Wastewater Discharge Retrieval Based on Stable Nighttime Light Imagery in China from 1992 to 2010
