While many scientists are studying snow, ice, and permafrost on the earth for clues to climate change, others are flying a jet into the tropopause, the boundary between the lower atmosphere (troposphere) and the stratosphere. They are interested in this region because the buildup of greenhouse gases has altered it in ways that are not fully understood.

To gather the data, scientists are using a jet aircraft that will fly about a dozen missions across North America, ranging up to 47,000 feet high. The plane will take sensors through the top of the troposphere and into the stratosphere. Samples of air will determine the movements and concentrations of a number of gases.

One of the goals of the project, known as START 08 (Stratosphere-Troposphere Analyses of Regional Transport), is to learn more about water vapor and ozone, which act as potent greenhouse gases by trapping thermal radiation in the atmosphere.  

 The tropopause is too high to observe with most ground-based instruments or most aircraft, and too low for satellites to view with great detail. The START aircraft allows the detail that researchers need to determine how weather patterns stir up chemicals near the tropopause and how the tropopause’s changing chemical composition influences global climate.  Over the next two years, climate scientists will use observations from START and other sources to adjust computer models that simulate Earth’s climate. These models will be used for the next round of reports by the Intergovernmental Panel on Climate Change (IPCC), which are likely to be issued about 2012.  The IPCC, a recipient of the Nobel Peace Prize, operates under the auspices of the United Nations Environment Programme and the World Meteorological Organization.