Pollution Around the World

This illustration shows a hypothetical plume and possible series of flight patterns during the PACDEX field project. When a major plume of dust and pollutants begins blowing off Asia, the G-V would fly from Boulder to Anchorage, where it would refuel, and then fly on to Yokota Air Base, Japan. It would then conduct a series of flights for about a week in and around the plume as the plume moves over the ocean to North America. If pollution stayed in one place, scientists could easily determine where it formed. But, like so much of the atmosphere, pollution is in regular motion. Winds carry particles and gases aloft, blowing them around the globe until they disintegrate or fall back to Earth. This creates a challenge for public policy leaders trying to control the sources of pollution.

A major focus of NCAR research is tracking the paths of pollutants. For example, scientists using a computer model in 1998 found that 50 to 60% of sulfate aerosol in the Pacific Northwest appears to come from industrialized Asia—which may complicate efforts to keep the Northwest’s air clean. A large project in the summer of 2004 tracked pollution plumes as they leave the U.S. Northeast and head across the Atlantic.

Simulated Particle Trajectories at 400K Potential Temperature

This simulation depicts a key finding that global mixing occurs in the lower stratosphere in only 60 days. It shows the trajectories of weightless particles released into the troposphere over the tropics at an altitude approximately 17 kilometers.


In 1999, NCAR launched an Earth-orbiting monitor known as Measurements of Pollution in the Troposphere. MOPITT measures carbon monoxide from aboard NASA's Terra spacecraft as it circles Earth from pole to pole 16 times daily. Scientists at NCAR are blending the new data with output from a computer model of Earth's atmosphere to develop the world's first global long-term maps of pollution in the lower atmosphere.

To learn more about the impacts of pollution, scientists compare the atmosphere in relatively unpolluted places, like remote islands in the Pacific Ocean or Antarctica, with the air over industrialized regions. This way, scientists hope to understand the differences between “clean” and “dirty” air. But pollution is so far flung it even reaches areas once thought pristine. For example, NCAR scientists and their colleagues have sampled aerosols in the air over the southern Indian Ocean, far downwind of India.