Abstract
Measuring the angular distribution of upwelling artificial light is important for modeling light pollution, because the direction of emission affects how light propagates in the atmosphere. We characterize the angular distributions of upwelling artificial light for Europe and northern Africa in 2018, based on night time radiance data for clear nights without twilight and moonlight from the VIIRS–DNB sensor on board the Suomi NPP satellite. We find that in general, suburban areas of major cities emit more light at larger zenith angles, whereas the opposite can be seen at the city centers, where the highest radiance is directed upward. The mean numbers of overflights for the year is 83, meaning that there are on average approximately seven suitable overflights per month. Future analysis may consider using moonlight models to compensate for the retrieval of moonlit scenes and analyzing data from different years in order to expand the amount of available data. As the VIIRS–DNB sensor on board the NOAA–20 satellite (launched 2017) has almost the same design, this method can also be extended to the data taken by NOAA–20.
Highlights
Data products from satellite remote sensing are often used in modeling of light pollution because they provide wider spatial coverage than ground-based measurements, which in turn is useful for identifying potential areas of interest for more in-detail groundbased measurements [1]
Suomi National Polar-orbiting Partnership (S–NPP) satellite in October 2011, opens up an opportunity of quantifying the angular distribution of artificial light using a space-borne sensor, which was only possible to be done by aerial imaging in the past [5,6], and will provide additional constraints for light pollution models over a wide area of the Earth’s surface
The Visible/Infrared Imaging Radiometer Suite (VIIRS)–Day–Night Band (DNB) sensor has a swath width of ca. 3,000 km across the track, and the S–NPP satellite which carries the VIIRS–DNB sensor is on a sun synchronous orbit, which means that the sensor observes the same surface element of the Earth at different time of night and from different direction each night
Summary
Data products from satellite remote sensing are often used in modeling of light pollution because they provide wider spatial coverage than ground-based measurements, which in turn is useful for identifying potential areas of interest for more in-detail groundbased measurements [1]. Currently most wide-area light pollution models (for example the World Atlas of artificial light [3]) do not incorporate measured data of angular distribution from space as an input. Suomi National Polar-orbiting Partnership (S–NPP) satellite in October 2011, opens up an opportunity of quantifying the angular distribution of artificial light using a space-borne sensor, which was only possible to be done by aerial imaging in the past [5,6], and will provide additional constraints for light pollution models over a wide area of the Earth’s surface. 3,000 km across the track, and the S–NPP satellite which carries the VIIRS–DNB sensor is on a sun synchronous orbit, which means that the sensor observes the same surface element of the Earth at different time of night and from different direction each night. The S–NPP satellite serves as a prototype satellite of the Joint Polar Satellite System (JPSS) series weather forecast satellite, with the first of the series, NOAA–20, launched in October 2017
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