Study Finds Asian Monsoon Carries Pollution Into the Stratosphere

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The observations also showed hydrogen cyanide, which can last in the atmosphere for several years before breaking up, moving over the tropics with other pollutants and then circulating globally.

The researchers used computer modeling to simulate the movement of hydrogen cyanide and pollutants from other sources, including industrial activity. The model indicated that emissions of pollutants over a broad region of Asia, from India to China and Indonesia, were becoming entrained in the monsoon circulation and transported into the lower stratosphere.

The study suggests that the impact of Asian pollutants on the stratosphere may increase in coming decades because of the growing industrial activity in China and other rapidly developing nations.

In addition, climate change could alter the Asian monsoon, although it remains uncertain whether the result would be to strengthen or weaken vertical movements of air that transport pollutants into the stratosphere.

Randel says more research is needed into the possible effects of the pollutants. When sulfur rises into the stratosphere, it can lead to the creation of small particles called aerosols that are known to influence the ozone layer.

The monsoon transport pathway may also have effects on other gases in the stratosphere, such as water vapor, that affect global climate by influencing the amount of solar heat that reaches Earth.

This is a vivid example of pollutants altering our atmosphere in subtle and far-reaching ways.

—William Randel

In addition to the NCAR researchers, the team included scientists from the Universities of Waterloo and Toronto in Canada, the University of York in England, and the University of Edinburgh in Scotland. The research was funded by the National Science Foundation (NSF), NCAR’s sponsor, along with NASA and the Canadian Space Agency.

Resources

• William J. Randel, Mijeong Park, Louisa Emmons, Doug Kinnison, Peter Bernath, Kaley A. Walker, Chris Boone, Hugh Pumphrey (2010) Asian Monsoon Transport of Pollution to the Stratosphere. Science doi: 10.1126/science.1182274