|
December 15, 2004
NASA SCIENTISTS DISCUSS GIANT ATMOSPHERIC BROWN CLOUD
NASA scientists announced a giant, smoggy atmospheric brown cloud, which forms over South Asia and the Indian Ocean, has intercontinental
reach. The scientists presented their findings today during the American Geophysical Union Fall meeting in San Francisco.
The scientists discussed the massive cloud’s sources, global movement and its implications. The brown cloud is a moving, persistent air mass
characterized by a mixed-particle haze. It also contains other pollution, such as ozone.
“Ozone is a triple-threat player in the global environment. There are three very different ways ozone affects our lives,” said Robert
Chatfield, a scientist at NASA’s Ames Research Center, Moffett Field, Calif. “A protective layer of good ozone, high in the atmosphere,
shields us from deadly ultraviolet light that comes from the sun. Second, bad or smog ozone near the surface of Earth can burn our lungs and damage
crops. In our study, we are looking at a third major effect of ozone, that it can warm the planet, because it is a powerful greenhouse gas,”
Chatfield said.
“We found both brown cloud pollution and natural processes can contribute to unhealthy levels of ozone in the troposphere where we live and
breathe. Some ozone from the brown cloud rises to high enough altitudes to spread over the global atmosphere,” Chatfield explained. Ozone from
the Earth’s protective stratospheric layer, produced by natural processes, can migrate down to contribute to concentrations in the lower
atmosphere, according to the scientists.
The researchers studied the intercontinental smog ozone processes associated with the brown cloud over South Asia. They used a NASA technique that
combines data acquired by satellites with ozone data measured by instruments on special weather balloons.
The ozone-monitoring instrument on NASA’s Aura satellite is providing data about the brown cloud. “The beautiful, high- detail images
from this instrument promise to help us sort out our major questions about how much of the tropospheric ozone is from pollution and how much is from
natural factors,” Chatfield said.
Analysis shows ozone in the lower atmosphere over the Indian Ocean comes from the intensely developed industrial- agricultural areas in the
region. The southern pollutant buildup has long-range effects, often traveling across Africa, further than the brown cloud of particles, according to
researchers.
To access technical information about the brown cloud study on the Web, visit:
http://geo.arc.nasa.gov/sgg/chatfield/ recentRes.html
For information and images related to this story on the Web, visit:
http://www.nasa.gov/vision/earth/environment/ brown_cloud.html
For information about NASA and agency programs on the Internet, visit:
http://www.nasa.gov
###
Contacts:
Gretchen Cook-Anderson
Headquarters, Washington
Phone: 202-358-0836
John Bluck
Ames Research Center, Moffett Field, Calif.
Phone: 650/604-5026/9000
|
|
Asian Brown Cloud
A dense blanket of polluted air hovers over central eastern China. The ‘Giant Brown Cloud’ is an unhealthy mix of ozone, smoke, and
other particles from human activities. Credit: NASA/ORBIMAGE
Good vs Bad Ozone
Ozone can be either good or bad depending on its location. “Good” ozone located in the stratosphere blocks harmful ultraviolet
radiation from reaching us, while “bad” ozone in the lower atmosphere acts as a pollutant that degrades the quality of the air we
breathe. Credit: NASA
Urban Sprawl
Urban in southern China increased by more than 300% between 1988 and 1996. NASA’s Landsat satellite obtained images of the region from 1973 to
2001. Population growth is one factor affecting the size of the “Giant Brown Cloud.” Credit: NASA
Far-Reaching Effects
Particles from airborne pollution, such as the “Giant Brown Cloud,” can travel all around the globe. In April of 2001, NASA satellites
saw a massive dust storm appear over China. The densest portion of the aerosol pollution traveled east over Japan, the Pacific Ocean, and, within a
week, the United States. Credit: NASA
Clues Beyond Our Planet
Researchers are currently studying Saturn’s moon, Titan, to better understand the connections between atmospheric haze, winds, and sunlight.
Comparing the atmospheres of Titan and Earth can shed light on basic smog processes on both worlds. Credit: NASA
Keeping Tabs on our Atmosphere
Aura, NASA’s latest next generation Earth-observing satellite, will study ozone levels in our atmosphere with its Ozone Monitoring Instrument
(OMI). This simulation shows the OMI hard at work. For more information on the Aura project, please visit: http://www.nasa.gov/aura Credit: NASA
|
