NASA has unveiled a new global view and animation of Earth's city night lights from space in a composite assembled from satellite data. The global composite image was constructed with cloud-free night images from the NASA-NOAA satellite Suomi NPP.
The images show natural and man made lights across the planet in detail never before obtained.
NASA released the new, higher resolution composite imagery at a news conference of the American Geophysical Union in San Francisco.
According to NASA, Suomi NPP compiled data used to construct the images over 312 orbits it completed during nine days in April 2012 and 13 days in October 2012. The satellite, using its special instruments, took a shot of every part off the Earth's land surface. The new data set was then combined with previous Blue Marble imagery of the Earth to deliver powerfully realistic views of our planet from space.
While many satellites are able to observe the Earth during the day by taking advantage of solar illumination, the special instruments aboard the NASA-NOAA Suomi National Polar-orbiting Partnership (NPP) satellite that was launched last year, can observe the Earth during night hours. The instrument can capture images in the dark with or without lunar illumination and produce crisp views of Earth's atmosphere, land and waters.
NASA Earth Observatory/Suomi NPP
This image of the continental United States at night is a composite assembled from data acquired by the Suomi NPP satellite in April and October 2012. The image was made possible by the satellite's 'day-night band' of the Visible Infrared Imaging Radiometer Suite (VIIRS), which detects light in a range of wavelengths from green to near-infrared and uses filtering techniques to observe dim signals such as city lights, gas flares, auroras, wildfires and reflected moonlight."
NASA explains that Suomi NPP's "Black Marble" image was composed using the satellite's "day-night band" of the Visible Infrared Imaging Radiometer Suite (VIIRS), which detects light in the electromagnetic radiation (EMR) spectrum from green to near-infrared. According to NASA, the day-night band of the VIIRS is able to detect nocturnal glows as faint as the light from a ship at sea in the night.
Althoutgh satellites in the U.S. Defense Meteorological Satellite Program have observed the Earth using low-light sensors for more than four decades, the VIIRS day-night band has a much more powerful resolution and can deliver a better view of Earth's night lights.
The VIIRS uses a filtering process to detect relatively dim city lights, gas flares, auroras, wildfires and even reflections of moonlight, NASA says.
NASA Earth Observatory/Suomi NPP
"On Oct. 13, 2012, the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi NPP satellite captured this nighttime view of the Nile River Valley and Delta."
Scientific researchers will find higher resolution of the VIIRS day-night band images a valuable source of new data about the Earth's atmospheric and surface conditions. Steve Miller, a researcher at NOAA's Colorado State University Cooperative Institute for Research in the Atmosphere, said: "For all the reasons that we need to see Earth during the day, we also need to see Earth at night. Unlike humans, the Earth never sleeps."
The BBC reports that the VIIRS will be used mostly for collecting meteorological data. VIIRS can be used to observe various atmospheric phenomena relevant to weather forecasting such as cloud, snow and fog, even in the absence of moonlight. According to NASA, because of its special night observation capabilities, VIIRS can render a better view of storms and other weather phenomena such as fog that are difficult to detect and observe with infrared/thermal sensors.
NASA reports that the day-night band was used to observe Hurrican Sandy making land fall over New Jersey on October 29 . It also captured night images that showed the power outages which plunged large areas of the US into pitch darkness.
Mitch Goldberg, program scientist for NOAA's Joint Polar Satellite System, said; "NOAA's National Weather Service is continuing to explore the use of the day-night band. The very high resolution from VIIRS data will take forecasting weather events at night to a much higher level."
NASA explains the unique attributes of its new "day-night band" system:
"Unlike a camera that captures a picture in one exposure, the day-night band produces an image by repeatedly scanning a scene and resolving it as millions of individual pixels. Then, the day-night band reviews the amount of light in each pixel. If it is very bright, a low-gain mode prevents the pixel from oversaturating. If the pixel is very dark, the signal is amplified."
According to Miller, "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." He added: "The night is nowhere as dark as we might think... we don't have to be in the dark anymore, either."
James Gleason, Suomi NPP project scientist at NASA's Goddard Space Flight Center in Greenbelt, Md., said: "The remarkable day-night band images from Suomi NPP have impressed the scientific community and exceeded our pre-launch expectations."
Digital Journal reported that Suomi NPP is the first of a new generation of Earth-observing satellites being deployed in orbit to observe the Earth.
The National Polar-Orbiting Operational Environmental Satellite System (NPOESS) Preparatory Project, or NPP, was renamed "Suomi NPP" on January 24, 2012 in honor of the late Verner E. Suomi of the University of Wisconsin. Suomi was a meteorologist at the University of Wisconsin widely recognized as the "father of satellite meteorology."