The NOAA/NASA Suomi National Polar-orbiting Partnership (Suomi NPP) satellite has photographed holiday lights around the world. A NASA scientist has led this study in order to understand how patterns in decorative lights change over time.
Christmas lights in the United States and Europe were among the brightest features studied, in addition to those lighted in the Muslim world during the holy month of Ramadan. Researchers discovered that lights around the Middle East were 50 percent brighter than normal during Ramadan. In the western world, the holiday season is 20 to 50 percent more luminous than during the rest of the year.
The Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard Suomi is able to record lights all over the nighttime side of the Earth. Moonlight, clouds and particles in the air were digitally removed from images taken by the satellite through the use of an advanced algorithm. Photographs from that camera were compiled into "Earth at Night" images, released to the public in 2012.
Researchers examined light output for 70 American cities from 2012 to 2013 in order to establish a baseline of light usage.
"It's a near ubiquitous signal. Despite being ethnically and religiously diverse, we found that the U.S. experiences a holiday increase that is present across most urban communities. These lighting patterns are tracking a national shared tradition," Miguel Román from the the Suomi NPP Land Discipline Team and the Goddard Space Flight Center, said.
Hanukkah, which is celebrated on various dates each year, started on December 16 and runs through Christmas Eve.
Researchers found the greatest change in illumination was seen in suburban areas and the outskirts of cities. Regions in the center of cities were between 20 and 30 percent brighter during the holiday season than during the rest of the year, the images revealed.
Holiday lights start brightening cities on the day after Thanksgiving, and continued through New Years Day, the enhanced images show.
Román and his team were only able to study southern cities, due to the effect of light reflecting of of snow. In the United States, researchers focused primarily on urban areas south of St. Louis and Washington D.C., as well as California, between San Francisco and Los Angeles. The team also looked at Puerto Rico, known for its festive lights and long holiday season.
Lights in the Muslim world vary according to the country. Saudi Arabian cities are well lit, as observers fast during the day, and celebrate after sunset. Turkey showed the least amount of additional lighting during Ramadan.
Powering lights is a major draw on energy systems in urban areas, leading to greenhouse gas emissions, promoting global climate change.
Results of the study were the subject of a presentation delivered to the American Geophysical Union's Fall Meeting, held in San Francisco.
