Suomi National Polar-orbiting Partnership (S-NPP) Research
The Suomi National Polar-orbiting Partnership (S-NPP) satellite, precursor to the Joint Polar Satellite System (JPSS) constellation, includes a special low-light sensor (the Day/Night Band) as part of the Visible/Infrared Imager/Radiometer Suite (VIIRS). The DNB is capable of detecting extremely low levels of visible light. For the first time, we are able to use calibrated measurements of moonlight in a way that is analogous to daytime visible channels, providing a paradigm shift to nighttime remote sensing applications (heretofore relegated to limited infrared-based techniques). To realize the full potential of moonlight observations by the Day/Night Band, one must know the highly variable incoming lunar irradiance. Unlike sunlight, moonlight is highly variable over the ~28 day lunar cycle. Recent work toward characterizing this signal, involving detailed Sun/Earth/Moon geometry prediction, spectrally resolved lunar albedo, non-linear phase function, and underpinning radiative transfer theory will provide the tools needed for developers to exploit the Day/Night Band quantitatively for numerous atmospheric and surface applications.