A satellite instrument designed to improve weather forecasts has provided a wealth of data on the flow of heat-trapping carbon dioxide in the atmosphere, scientists said Tuesday.
The data also verified a mechanism in which rising temperatures increase the rate of ocean evaporation, and the increased water vapor, also a potent greenhouse gas, raises the earth’s temperatures further.
The Atmospheric Infrared Sounder — called AIRS for short — aboard NASA’s orbiting Aqua spacecraft measures temperature and cloud cover by recording infrared emissions across the entire globe twice a day. The data helps meteorologists predict major storms.
More careful analysis of the data, collected since the satellite’s launching in 2002, has also revealed levels of carbon dioxide, methane, ozone and other gases in the midtroposphere — the atmosphere between 3 and 7 miles above the earth’s surface.
“In essence, we’re videotaping the atmosphere and its constituents,” Thomas Pagano, the instrument’s project manager, said at a news conference in San Francisco during a meeting of the American Geophysical Union.
Carbon dioxide does not mix evenly in the troposphere, the scientists said. This allows them to track movement of the gas to see where it ends up, and predict whether oceans can continue to absorb much of it.
Carbon dioxide from factories, car travel and other human activity is believed by most scientists to be driving the warming of the planet. Levels of carbon dioxide in the air are currently approaching 390 parts per million, up from roughly 280 in the preindustrial age.
But the carbon dioxide itself only accounts for about a third of the increased trapping of heat on earth.
Using the AIRS data, Andrew Dessler, a professor of atmospheric sciences at Texas A&M University, looked at the El Niño cycle of warming and cooling waters in the tropical Pacific.
As expected, water vapor increased when waters were warm and fell when temperatures cooled, and the measurements fit closely with climate models previously developed by scientists.
Thus, warming from rising carbon dioxide should also lead to increased water vapor and additional warming, doubling the warming effect of the carbon dioxide.
“Water vapor is really not much of an uncertainty anymore,” Dr. Dessler said.
Other heat-trapping gases like methane and ozone, also measured by AIRS, are known to contribute to global warming as well. http://www.nytimes.com/2009/12/16/science/space/16carbon.html?_r=1&scp=1&sq=Weather%20Device&st=cse
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