NASA, NOAA and CIRA scientists unveiled new nighttime images of Earth from the NASA/NOAA Suomi NPP satellite at the American Geophysical Union annual meeting in San Francisco on Wednesday, December 5, 2012.
In a groundbreaking study published in the Proceedings of the National Academy of Sciences (PNAS) by CIRA research scientist Steve Miller along with colleagues from NOAA, Northrop Grumman, and the U.S. Department of Defense, it was discovered that the Day/Night Band (DNB) of the Visible/Infrared Imager Radiometer Suite (VIIRS) aboard Suomi NPP is able to detect clouds on dark nights that are illuminated by the very low light from air glow and starlight. “This is a significant find in collaboration with our partners and could help scientists around the world with this knowledge that a combination of starlight and the upper atmosphere’s own subtle glow can help satellites see Earth’s clouds on moonless nights,” said Miller.
During the day, ultraviolet radiation from the sun bombards Earth’s upper atmosphere and breaks apart gaseous molecules and atoms. During the night, these molecules and atoms recombine emitting faint visible light — called air glow — in the process. Most weather satellites aren’t sensitive enough to see city lights. Reflected moonlight is much fainter at nearly a million times fainter than sunlight. And air glow/starlight sources are 100-1000 times fainter still.
This new ability to see clouds at night could have significant implications for weather and climate observations for forecasters and research scientists alike.