A Dynamic Lunar Spectral Irradiance Data Set for NPOESS/VIIRS Day/Night Band Nighttime Environmental Applications

In anticipation of the first fully calibrated nighttime low-light measurements from the National Polar-orbiting Operational Environmental Satellite System´s Visible/Infrared Imager/Radiometer Suite (VIIRS) Day/Night Band (DNB), a simple model has been developed for quantifying the highly variable top-of-atmosphere spectral irradiance (in watts per square meter per micrometer) from Earth´s only natural satellite-the Moon. Based on the state-of-the-art in solar source observations, lunar spectral albedo data, and an account for the time-varying Sun/Earth/Moon geometry and lunar phase, the model produces 1-nm resolution irradiance spectra over the interval [0.3, 1.2 mum] for a given date and time. Convolving the spectra with the sensor response function of the VIIRS/DNB allows for the conversion from measurements of upwelling radiance to equivalent lunar reflectance [i.e., 0%-100%]-enabling quantitative nighttime multispectral applications that have heretofore been restricted to the daytime hours for lack of visible reflectance information. In the interest of advancing research in nighttime environments, we present here the development and validation of a lunar spectral irradiance database, supply auxiliary data and tools necessary for computing temporally dependent values, and discuss some of the environmental applications enabled by this utility.