Supporting article V: Using satellite images to track the culprits of the various green-house gasses trapped in the 15 km thick ozone layer.
Satellites Show Local Air Pollution Has Global Reach
By Robert Roy Britt
Senior Science Writer
posted: 11:20 am ET
30 May 2002
Walking through the streets of the Zambian capital of Lusaka in September of 2000, NASA researcher Anne Thompson watched city workers pile a year’s worth of dead leaves, brush and garbage into newly dug trenches and torch it all. Residents burned their own garbage in their backyards. Poorly maintained cars sputtered by, belching thick smoke into the air.
In a few months, Thompson now knows, pollution created in similar scenes across Africa and South America will again drift high into the atmosphere, out over the Atlantic Ocean and pile up, making it nearly impossible to figure out exactly where any of it came from.
Meanwhile, ozone and other pollutants from factories and cars in the United States streams across the Atlantic at lower altitudes, ending up in Europe.
One country’s way of life is another country’s pollution, Thompson has learned by studying data from satellites and atmospheric balloons over the past 10 years.
“Pollution is a global phenomenon,” says Thompson, of NASA’s Goddard Space Flight Center. “We do it to Europe. Europe does it to Asia. Asia does it to us.”
Thompson and her colleagues, in their latest work, have created the first cross-sectional view of ozone in the tropical portion of the troposphere, a layer of the atmosphere that begins at the surface and extends about to about 50,000 feet [15 kilometers]. This so-called low-level ozone is a greenhouse gas that is a byproduct of reactions from pollutants generated in the burning of garbage, gas and other fuels. She will present her findings Friday at a meeting of the American Geophysical Union in Washington D.C.
In a telephone interview, Thompson explained how pollutants travel the globe at the whim of prevailing air currents. Her work monitored just ozone, but it is somewhat of a proxy for other pollutants that waft similarly through the air, she said.
From South America, the bulk of low-level ozone generated in excess of naturally occurring levels tends to rise as much as 6-7 miles (10-12 kilometers) into the atmosphere. There, it drifts out over the Atlantic and stalls out. From Africa, the pollutants drift in the opposite direction, also ending up in the Atlantic.
A pile-up occurs south of the Equator that generates ozone levels typically twice as high as over the Pacific Ocean.
Between August and November, which corresponds to the burning seasons in South America and Africa, it gets worse. Atlantic ozone levels can be four to five time higher than what is measured over the Pacific. Scientists had noted the pile-up before, but now its sources have been probed by a series of balloons launched every week from 10 tropical countries over the past four years.
“This solves a decade-old mystery about where the Atlantic ozone was coming from,” Thompson said.
It’s not clear if the pile-up causes any local harm, the researcher said. But the extra ozone is known to contribute to warmer terrestrial temperatures by trapping the Sun’s energy.
The idea that pollution gets around is not new. But Thompson’s work points to a future in which scientists will be able to use balloons and satellites to track the movement of airborne pollution well enough to figure out who put what where — an increasingly important political issue as nations seek to cooperate (or not) on curbing global pollution.
Thompson and her colleagues plan to develop similar observing strategies to reveal how pollution moves near highly population regions of the Northern Hemisphere. Their eventual goal is to track pollution not just from country to country, but from state to state and even from one city to another.
The ozone study involved cooperation from the National Oceanic and Atmospheric Administration as well as scientists in Japan, Indonesia, Brazil, Kenya, South Africa, Java, Suriname and four Pacific Islands.