Spatial, Temporal and Spectral Variation of Light Pollution and its Sources: Methodology and Results

From the night images in panchromatic band obtained by the Earth observation satellites (DMSP / OLS and SNPP / VIIRS / DNB) the temporal evolution (at a global and regional level) of public lighting expenditure has been studied. For this, a method of intercalibration of the data of different missions has been designed, which has provided, as a first result and using data from the DMSP / OLS satellite, the reconstruction of the evolution of public lighting expenditure in Spain between 1992 and 2012, broken down into the different provinces. An analysis of the SNPP / VIIRS / DNB satellite images that have been applied for the determination of public lighting expenditure in the countries of the European Union and to study the variation of light pollution has been carried out as an additional validation of the method. in the municipalities of the Deltebre region. A study of the scientific use of the images taken with digital camera (DSLR) from the International Space Station (ISS) for studies of light pollution has been carried out. It is demonstrated in this work that the type of emitting spectrum of the sources of light pollution can be estimated by color-color diagrams using the three bands of the images and that it is possible to determine the type of lighting technology from the images taken from the ISS. In addition to the classification of sources using synthetic photometry, the absolute photometric calibration of the images was carried out using differential photometry of stellar fields and sources on the ground. As a first step for the scientific exploitation of the nocturnal images of the Earth that are stored in the NASA repository, a citizen science program has been created for the classification, location and geographic referencing of the images. More than 130,000 images have been classified, more than 3000 located, and more than 700 georeferenced. Other methods of capturing nighttime images of sources of light pollution have been explored, such as aerial techniques with hyperspectral and DSLR cameras, from a balloon and using drones. The radiances measured in the images obtained from the satellites have been related to the brightness of the night sky measured from the ground. To gather the necessary information, a method has been developed for the exploration of the spatial variation of the sky brightness that has been applied to the Madrid region, obtaining a map of the sky brightness in the whole region. The temporal variation has been determined with fixed stations of SQM type photometers. Finally, the spectral variation of the sky brightness was determined by continuous monitoring of the sky spectrum in Madrid with the AstMon sky-wide camera and with the SAND spectrograph. This set of measurements constitutes a fundamental data base for the application of models for the diffusion of light pollution through the atmosphere and allows us to conclude that the sky brightness is physically related to the diffuse emission observed in satellite images.This is a translatio