A new look at daily data from the Suomi NPP satellite, NASA scientist have identified how patterns in nighttime light intensity change during major holiday seasons.
According to the data, nighttime lights around many major U.S. cities shine 20 to 50 percent brighter during Christmas and New Year’s when compared to light output during the rest of the year. In some Middle Eastern cities, nighttime lights shine more than 50 percent brighter during Ramadan than the rest of the year.
The maps above and below show the change in lighting intensity and location in Texas and Louisiana (top) and California, Arizona, Nevada, and northwest Mexico. The map compares the nighttime light signals from December 2012 and 2013 to the average light output for the rest of 2012 to 2014. Green shading marks areas where light usage increased in December; yellow marks areas with little change; and red marks areas where less light was used.
Suomi NPP, a joint NASA/National Oceanic and Atmospheric Administration (NOAA) mission, carries an instrument called the Visible Infrared Imaging Radiometer Suite (VIIRS) that detects light in a range of wavelengths from green to near-infrared as it flies over at roughly 1:30 a.m. and 1:30 p.m. each day. VIIRS has a low-light sensor, or “day-night band (DNB),” that can distinguish night lights tens to hundreds of times better than previous satellites. Scientists use the DNB to observe comparatively dim signals such as city lights, auroras, wildfires, and reflected moonlight.
In 2012, scientists released new composite maps of Earth at night that were created from VIIRS DNB data. Those images were stitched together nights when there were no clouds or moonlight over any given area.
The new analysis of holiday lights uses an advanced algorithm that filters out moonlight, clouds, and airborne particles in order to isolate the lights on a daily basis. The data from this algorithm can provide high-quality satellite information on light output across the globe, allowing scientists to track when and how brightly people illuminate the night.
In the United States, the lights started getting brighter on the day after Thanksgiving and continued through New Years Day, said Miguel Román, a scientist at NASA’s Goddard Space Flight Center and member of the Suomi NPP Land Discipline Team. Román and colleagues examined the light output from 70 U.S. cities in 2012 and 2013 as a first step toward determining patterns in urban energy use—a key factor in greenhouse gas emissions.