A New Frontier of Nighttime Environmental Sensing Brought to Light by the Suomi NPP VIIRS Day/Night Band

Optical-spectrum environmental satellite radiometers take advantage of solar reflectance information when it is available, but are limited at night to thermal infrared emission. The infrared offers poor thermal contrast for low clouds and surface features, limiting our ability to characterize the full diurnal behavior of many important weather and climate parameters. While a select few satellite sensors can detect lunar reflectance, technological limitations and the inconsistent availability of moonlight limit their utility. Here we show that the Day/Night Band (DNB) radiometer on the Suomi National Polar-orbiting Partnership (NPP) satellite has sufficient sensitivity to produce night time imagery of meteorological and surface features illuminated from principally a combination of reflected airglow and galactic starlight.

These findings expand substantially the possibilities for satellite-based nocturnal environmental monitoring, and hold significance to both the research and operational communities. Previously, low-light cloud observation at night was limited at best to periods of sufficient moonlight. The current findings suggest that some form of visible-based observation may be possible at all times—thereby extending many current satellite applications. This new capability is particularly relevant to addressing fundamental limitations of traditional infrared methods at night, to which numerous weather and climate applications fall casualty. In addition, the DNB's discovered ability to measure the primary airglow emission and resolve mesospheric wave structures provides connectivity between tropospheric disturbances and upper-atmospheric response. We expect that news of this new capability will lead to seminal, interdisciplinary research in the areas of atmospheric science (including the coupling of lower and upper atmospheric research) and near-space environment—and potentially motivate the design of a series of next-generation satellite remote sensing systems optimized to exploit these unconventional low-light signals.