Remote sensing satellites equipped with special sensors can detect faint light emissions in the visible and infrared wavelengths. This data, known as night light data, offers a wealth of information for researchers and policymakers.
Which satellites capture the night light?
Remote sensing satellites, like Suomi NPP and NOAA-20, carry sensors specifically designed to detect low-light levels. These sensors, often called Day/Night Bands (DNB), have high sensitivity in the visible and near-infrared (NIR) range, allowing them to capture the faint radiance emitted from artificial lights on Earth’s surface.
Do all the lights detected by the DNB sensors come from human settlements?
No. Natural phenomena like wildfires, auroras, and even airglow (atmospheric luminescence) can contribute to the signal. Through sophisticated filtering techniques, scientists remove these interferences, leaving behind data that primarily represents artificial light sources. Furthermore, a threshold value is applied to distinguish actual light emissions from background noise.
Night light maps offer a powerful tool for studying a wide range of topics, including:
Mapping Urbanization: Night lights provide a clear picture of urban extent and growth patterns.
Monitoring Economic Activity: Brighter areas often correlate with higher economic activity, aiding in regional GDP estimation.
Tracking Energy Consumption: Night light data can be used to assess energy use patterns and identify areas for potential energy efficiency improvements.
Understanding Social Development: Night light information can shed light on social development trends in different regions.
References:
Zhao, M., Zhou, Y., Li, X., Cao, W., He, C., Yu, B., Li, X., Elvidge, C.D., Cheng, W. and Zhou, C., 2019. Applications of satellite remote sensing of nighttime light observations: Advances, challenges, and perspectives. Remote Sensing, 11(17), p.1971.
Dai, Z., Hu, Y. and Zhao, G., 2017. The suitability of different nighttime light data for GDP estimation at different spatial scales and regional levels. Sustainability, 9(2), p.305.
