  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.
