Abstract: Artificial light is a key element of the urban nocturnal landscape. Despite its role in enabling diverse nocturnal human activities, artificial light is drawing growing concern for its adverse impacts on human health and ecosystems-a problem known as urban light pollution. Taking the megacity of Shenzhen as an example, we investigated the nighttime-light pattern based on high spatial resolution SDGSAT-1 GLI glimmer imagery. We found that light brightness in Shenzhen was dominated by low values, with the values of red band being significantly higher than those of other spectral bands. There was high spatial heterogeneity in the distribution of light brightness across all bands. The brightness and spectral composition of nighttime light diverged markedly across functional zones. Commercial areas exhibited the highest average brightness, whereas the residential areas showed moderate average brightness. Blue band showed the most pronounced differences in light brightness across functional zones (with a relative range difference of 26.76%). The light brightness proportion of blue band in commercial areas and green spaces was the highest, while a medium proportion was found in the residential areas, and the lowest proportion was found in the transportation areas and municipal areas. Light brightness decreased along the urban-rural gradient. The average brightness across different bands in urban centers was 1.4 times that of the suburbs and 8.5 times that of rural areas. The commercial areas exhibited the greatest urban-rural disparity, reaching a six-fold difference. Our results indicate that the commercial areas in urban center, the widely distributed residential areas, and green spaces are priority regions for light pollution control. We propose specific lighting management strategies, providing scientific support for alleviating urban light pollution.

Key words: functional zone, SDGSAT-1 GLI, spatial pattern, urban-rural difference