Earth has two different stratospheres, and aviation may be to blame

Jet engines roar over icy waters. Credit: NOAA

Scientists have long recognized that, on average, air pollution in the troposphere, or lower atmosphere, is worse in the Northern Hemisphere than in the Southern Hemisphere. That’s because nearly 90 percent of the global population, and a majority of urban and industrial pollution sources, are located north of the equator.

Now, an analysis of data gathered during a groundbreaking NOAA-NASA airborne research mission has found that the northern stratosphere, the layer right above the troposphere, is more polluted as well. Only in this case, the scientists believe emissions from a specific source--aviation exhaust—may be a main culprit.

In a study published in the journal Atmospheric Chemistry & Physics, scientists from NOAA’s Chemical Sciences Laboratory and CIRES report that measurements of very small particles and trace gases in the lower stratosphere taken aboard the NASA DC-8 research aircraft during the Atmospheric Tomography Mission (ATom) showed clear differences between the north and the south.

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