The most important sampling to date of biospheric and atmospheric chemistry in tropical rainforests will culminate in December, when National Science Foundation (NSF)-supported scientists complete a rare study of the African atmosphere. Ground-based and tower-mounted instruments and a research aircraft will support studies of biomass burning, rainforest-savanna boundaries and the influence of tropical vegetation on global air chemistry.
This fall's field work, which begins on Nov. 10, is the climax of a multiyear project called EXPRESSO, the Experiment for Regional Sources and Sinks of Oxidants. Leaders of the project are the NSF-supported National Center for Atmospheric Research (NCAR), in Boulder, Colorado; Paul Sabatier University, in Toulouse, France; the University of Brazzaville, in the Congo; and L'Institut Francais de Recherche Scientifique pour le Developpement en Cooperation in France.
"The EXPRESSO project is providing a comprehensive look at sources and sinks of ozone and other oxidants in the tropics," says Cliff Jacobs, program director in NSF's division of atmospheric sciences, which funds NCAR and EXPRESSO. "The central Africa region is one of several areas in the world that play an influential role in global chemistry cycles. EXPRESSO will help define the degree of influence central Africa has on these cycles."
Africa with its vast expanse of land near the equator, exerts a
powerful influence on tropical and global air chemistry. Huge
stretches of African savanna and rainforest are burned each fall and
winter for agricultural and territorial purposes. The fires produce
large amounts of hydrocarbons and oxides of nitrogen, which interact
with sunlight to produce ozone and other smoglike products -- often at
levels approaching those of a high-pollution day in a major city.
Satellite pictures show that the plumes of ozone stretch, at times, as
far as South America. EXPRESSO may s
Contact: Cheryl Dybas
National Science Foundation