The VIIRS Day/Night Band Lights Pathways Toward Improved Nocturnal Applications and Situational Awareness

Abstract:

The Visible/Infrared Imaging Radiometer Suite (VIIRS) sensor, carried on the Suomi National Polar-orbiting Partnership (NPP) and National Ocean and Atmospheric Administration (NOAA) Joint Polar Satellite System (JPSS), features the Day/Night Band (DNB)—a low-light visible sensor whose capabilities are unparalleled among optical imaging systems currently in-orbit. With its sensitivity to light at levels more than 250,000 times fainter than reflected sunlight, the DNB enables imaging and measurement of the environment via moonlight at 742 m resolution across its 3060 km wide swath. In addition, the DNB senses the light emissions from anthropogenic sources (e.g., cities, boats, gas flares), providing a unique proxy for human behavior and economic activity. This paper informs the user community on three important developments related to DNB research bearing relevance to the NOAA Satellite Proving Grounds and beyond. First, refinements to a lunar irradiance model tailored to the DNB provide better representation of the opposition surge effect near Full Moon, leading in turn to improved accuracy of quantitative nighttime products such as cloud properties. Second, the DNB has revealed a special case of marine boundary layer cloud false-alarm that affects passive infrared-based nighttime cloud detection techniques. Finally, the impacts of COVID-19 pandemic shutdowns have manifested as spatial/temporal variations in DNB-observed nighttime lights—occurring in both anticipated and sometimes surprising ways across local, regional, national, and international scales. These data contain potentially valuable information on how different societies or demographics respond to conditions that limit and alter their normal behaviors and rhythms. Correlations between changes of light on monthly timescales and other factors, including economic productivity, infection/recovery rates, and the juxtaposition of countries taking different postures on physical distancing measures, yield insights that help planners and decision makers understand the direct and indirect impacts of the pandemic. Through these examples of diverse utility, we are reminded that realizing the full potential of these novel DNB measurements require an expansion of our own mindset beyond the confines of any single research discipline.