Monitoring transition: Expected night sky brightness trends in different photometric bands

Abstract

Several light pollution indicators are commonly used to monitor the effects of the transition from outdoor lighting systems based on traditional gas-discharge lamps to solid-state light sources. In this work we analyze a subset of these indicators, including the artificial zenithal night sky brightness in the visual photopic and scotopic bands, the brightness in the specific photometric band of the widely used Sky Quality Meter (SQM), and the top-of-atmosphere radiance detected by the VIIRS-DNB radiometer onboard the satellite Suomi-NPP. Using a single-scattering approximation in a layered atmosphere we quantitatively show that, depending on the transition scenarios, these indicators may show different, even opposite behaviors. This is mainly due to the combined effects of the changes in the sources' spectra and angular radiation patterns, the wavelength-dependent atmospheric propagation processes and the differences in the detector spectral sensitivity bands. It is suggested that the possible presence of this differential behavior should be taken into account when evaluating light pollution indicator datasets for assessing the outcomes of public policy decisions regarding the upgrading of outdoor lighting systems.

Remote sensing of night lights: A review and an outlook for the future

“…This spectral shift will likely affect the ability to existing sensors such as VIIRS/DNB to quantify artificial lights from space, given that it is not measuring incoming light in the blue band (Figure 24). Modelling work recently done by Bará et al (2019) indicates that for certain transition scenarios (from HPS to LED), the VIIRS may detect reduction in artificial zenithal sky brightness, even if sky brightness in reality increases, due to the loss of the HPS line in the near-infra red, and the inability of the VIIRS to detect blue light. The emission of blue light from LED sources therefore requires future night-time sensos to include the blue channel (which is not covered by DMSP/OLS, VIIRS/DNB or Luojia-1), however blue light is scattered more (Kocifaj et al, 2019), and thus atmospheric haze removal techniques should be developed for night-time imagery, for future products.…”

A linear systems approach to protect the night sky: implications for current and future regulations

“…A set of widely used models are available to determine G(r 00 ,a 00 ; r 0 ,a 0 ; l) for different atmospheres and with different levels of analytic and numerical complexity. The interested reader may want to consult [23][24][25][26][27][28][29][30][31] for full details of the most used ones. Equation (A 4) can be interpreted as the result of an integral linear operator, L 2 , with parameters r 00 and a 00 , acting on the variables r 0 , a 0 and l of the spectral radiance of the outdoor lights, such that L(r 00 ,a 00 ,l) ¼ L 2 {L s }.…”

“…The K(r,r 0 ) PSF can be calculated by computing the effects of a single point source using suitable radiative transfer models and appropriate atmospheric characterization [23]. Several PSFs have been developed in the literature for the zenithal brightness, the brightness in arbitrary directions and the average brightness of the upper hemisphere relative to its nominal natural value [24][25][26][27][28][29][30][31]. The same procedures can be applied to determine the PSF for other linear indicators of the quality of the night sky.…”

Evaluation of Light Pollution in Global Protected Areas from 1992 to 2018

“…Additionally, blue light is a new emerging source of light pollution due to the increased use of LED lighting [60,68]. Unfortunately, such kinds of lights cannot be well-detected by DMSP/OLI and VIIRS/NDB [69], and its impact was not considered in our study.…”