BOULDER--Some of the most important sampling to date of biospheric and atmospheric chemistry in the tropical rainforest will culminate in November and December, when a team of scientists from the United States, France, Italy, the Central African Republic (CAR), and the Congo 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 November 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 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 Franais de Recherche Scientifique pour le Developpement en Cooperation. NCAR is operated by the University Corporation for Atmospheric Research under sponsorship of the National Science Foundation, which is providing substantial support for EXPRESSO.
With its vast expanse of land near the equator, Africa 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.
NCAR scientists have made several trips to Africa in the past three
years to take preliminary air samples, install instruments, and make
arrangements for this fall's field campaign. The
National Center for Atmospheric Research/University Corporation for Atmospheric Research