December 5, 2012
Satellite Helps Provide New High-Resolution Night Images Of Earth
[ Watch the Video: Video Of Earth at Night ]
Lee Rannals for redOrbit.com - Your Universe Online
The images show the glow of human-built cities throughout the Earth, giving the nocturnal peek at what it´s like looking down on the dark side of our planet.
The day-night band of the Visible Infrared Imaging Radiometer Suite (VIIRS) is sensitive enough to detect the nocturnal glow produced by Earth's atmosphere and the light from a single ship in the sea.
Satellites in the U.S. Defense Meteorological Satellite Program have made observations with low-light sensors for 40 years, but VIIRS day-night band can help better detect and resolve Earth's night lights.
"For all the reasons that we need to see Earth during the day, we also need to see Earth at night," said Steve Miller, a researcher at NOAA's Colorado State University Cooperative Institute for Research in the Atmosphere. "Unlike humans, the Earth never sleeps."
The day-night band observed Hurricane Sandy on the evening that it made landfall over New Jersey. Night images showed the widespread power outages that left millions in darkness in the wake of the storm.
VIIRS has helped to detect more complete views of storms and other weather conditions, such as fog, which is difficult to discern with infrared, or thermal sensors.
"NOAA's National Weather Service is continuing to explore the use of the day-night band," said Mitch Goldberg, program scientist for NOAA's Joint Polar Satellite System. "The very high resolution from VIIRS data will take forecasting weather events at night to a much higher level."
The day-night band produces an image by repeatedly scanning a scene and resolving it as millions of individual pixels. The band then reviews the amount of light in each pixel, and if it is very bright, a low-gain mode prevents the pixel from oversaturating.
"It's like having three simultaneous low-light cameras operating at once and we pick the best of various cameras, depending on where we're looking in the scene," Miller said.
The instrument can capture images on nights with or without the moonlight, helping to provide images of Earth's atmosphere, land, and ocean surfaces.
"The night is nowhere as dark as we might think," Miller concluded.
"The remarkable day-night band images from Suomi NPP have impressed the scientific community and exceeded our pre-launch expectations," said James Gleason, Suomi NPP project scientist at NASA's Goddard Space Flight Center in Greenbelt, Md.