This plot shows the concentration of carbon dioxide in Earth's mid-troposphere at various latitudes as measured by the Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua satellite. The colored lines represent different latitude bands that circle Earth, called "zones." The central latitude for each zone is given in the legend.

In the zone nearest the equator, represented by the green line, the swing in the amount of carbon dioxide is minimal since plants in the tropics remain green all year long. The seasonal intake of carbon dioxide by plants as they grow and then released when they die is not pronounced here.

In the middle latitudes at 32.5, 62.5, and -27.5 degrees latitude, we see greater swings in carbon dioxide due to the seasonal growth and die-off of plants in these regions.

Near the north pole, around 87.5 degrees latitude, we see the greatest amplitude in the seasonal cycle of carbon dioxide. But in this region the concentration of carbon dioxide is mostly driven by atmospheric circulation patterns that drive the gas from southern latitudes into the polar vortex, where the concentration of carbon dioxide is the highest on the planet.

AIRS is still in the process of validating its global carbon dioxide concentration levels, but the early results show excellent agreement with field measurements and model predictions.

About AIRS
The Atmospheric Infrared Sounder, AIRS, in conjunction with the Advanced Microwave Sounding Unit, AMSU, senses emitted infrared and microwave radiation from Earth to provide a three-dimensional look at Earth's weather and climate. Working in tandem, the two instruments make simultaneous observations all the way down to Earth's surface, even in the presence of heavy clouds. With more than 2,000 channels sensing different regions of the atmosphere, the system creates a global, three-dimensional map of atmospheric temperature and humidity, cloud amounts and heights, greenhouse gas concentrations, and many other atmospheric phenomena. Launched into Earth orbit in 2002, the AIRS and AMSU instruments fly onboard NASA's Aqua spacecraft and are managed by NASA's Jet Propulsion Laboratory in Pasadena, Calif., under contract to NASA. JPL is a division of the California Institute of Technology in Pasadena.

More information about AIRS can be found at http://airs.jpl.nasa.gov.