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Although originally designed to measure atmospheric water vapor and temperature profiles for weather forecasting, data from the Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua spacecraft are now also being used by scientists to observe atmospheric carbon dioxide. In the southern hemisphere, a belt of mid-tropospheric air containing enhanced concentrations of carbon dioxide emerged between 30 and 40 degrees south latitude. This belt had not previously been seen in any chemistry transport model. Subtropical storms track through this region, as do the cloud bands of the intertropical convergence zone near the equator, an area of low atmospheric pressure that forms where northeast and southeast trade winds meet. The researchers believe strong convection (thunderstorms) in this belt, and South America's high Andes Mountains, lift carbon dioxide from major sources on Earth's surface, such as the respiration of plants, forest fires and facilities for producing synthetic fuels and generating power. This carbon dioxide is then carried into the 'free troposphere,' the part of the troposphere that is too high to be influenced by Earth's surface. There, it becomes trapped in the mid-latitude jet stream, which transports it rapidly around the world. For more information on AIRS, visit the AIRS Project Web Site: http://airs.jpl.nasa.gov. The AIRS data products are available at http://daac.gsfc.nasa.gov/AIRS/index.shtml.
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