Earth Science

Edited by: Neeraja Sankaran C.R. Trepte, R.E. Viega, M.P. McCormick, "The poleward dispersal of Mount Pinatubo volcanic aerosol,"

April 3, 1995

Edited by: Neeraja Sankaran
C.R. Trepte, R.E. Viega, M.P. McCormick, "The poleward dispersal of Mount Pinatubo volcanic aerosol," Journal of Geophysical Research, 98:18563-73, 1993. (Cited in 12 publications through January 1995)

Comments by Charles R. Trepte, Science Applications International Corp., Hampton, Va. 23681

This paper describes the distribution of aerosols emitted from the 1991 eruption of Mount Pinatubo in the Philippines. The aerosols, primarily tiny droplets of sulphuric acid, were tracked by a National Aeronautics and Space Administration remote sensing satellite as they dispersed into the stratosphere at tropic and subtropic latitudes for the first 10 months after the eruption.

Charles Trepte, an atmospheric scientist with Science Applications International Corp., a private, Hampton, Va.- based consulting firm that provides atmospheric-research support for NASA's Langley Research Center, also located in Hampton, describes the project as "an excellent opportunity to try to understand how material is transported into the lower stratosphere. That's important to know because we've had all this discussion about how greenhouse gases affect the ozone layer.

"But we really don't understand how these chemicals, which enter the stratosphere through the tropics, become [transported] to high latitudes and ultimately to polar regions where the ozone hole occurs. It was an excellent test case to better understand poorly known transport processes."

Although Science Applications was an integral collaborator in the study, Trepte himself took part in this investigation while working on his Ph.D. in the department of atmospheric and oceanic sciences at the University of Wisconsin, Madison, another partner in the project.

Trepte recounts that as the research team examined the aerosol data, it became apparent that the distribution of wind-borne chemicals in the atmosphere was more complex than they had previously envisioned.

"There's a phenomenon in the tropics called the quasi-biennial oscillation," he explains. "Over the tropics in the stratosphere, the wind reverses from easterly to westerly every 28 months, on average.

"What the aerosol data showed is that when the winds are easterly, chemicals in the stratosphere tend to stay at tropical latitudes, not moving into higher latitudes as quickly as people had first thought."

This knowledge, Trepte maintains, adds yet another piece to the complex puzzle of formulating global circulation models: "What information like this does is allow modelers to go back and improve their models." Data like this will "ultimately improve the way they can make predictions on the fate of ozone or climate in general."

Trepte speculates that the article has been more frequently cited than most papers in this field because its findings are useful to several earth-science subspecialties, including atmospheric chemistry and global warming: "It really did resonate with a lot of different disciplines."

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