Results from a Scripps-led international experiment conducted in the Indian Ocean during February and March 1999 are helping scientists to unravel mysteries about climate processes related to air pollution and global warming.

The $25 million Indian Ocean Experiment, or INDOEX, involved more than 150 scientists from a dozen nations in a comprehensive field study to resolve how the interactions of pollution and clouds affect solar heating and climate in the region. Co-chief scientists were V. Ramanathan, director of the Scripps Center for Clouds, Chemistry and Climate (C4), and Paul J. Crutzen formerly of the Max Planck Institute for Chemistry in Germany and now an adjunct professor at Scripps. Major funding for INDOEX came from the National Science Foundation.

INDOEX scientists investigated atmospheric pollutants known as aerosols-natural and human-produced particles that are the result of industrial and automobile emissions, various types of burning, and airborne soil dust. The Indian Ocean is a perfect laboratory because it is the only place on Earth where pristine air from Antarctica directly converges with heavily polluted air from India and Asia.

INDOEX included intensive measurements of solar radiation, atmospheric chemistry, and cloud properties. These were made by hundreds of instruments on two ships, three aircraft, several satellites, and at five ground stations. Analysis of the data is under way and promises to produce crucial information needed to develop more accurate global climate prediction models, according to Ramanathan.He reports that widespread pollution was found over large sections of the region.

"There was a brownish haze layer over the Indian Ocean almost 1,000 miles off the coast," Ramanathan said. "It appeared as if the whole Indian subcontinent were surrounded by a mountain of pollution."

Preliminary results indicate aerosol pollutants scatter incoming solar radiation and reduce the amount of energy reaching the ocean's surface by as much as 10 percent. This finding raises serious questions concerning the impact pollution may have on climate processes and marine life.

The INDOEX headquarters were in the city of Malé in the Republic of Maldives, an island nation about 350 miles southwest of the tip of India. The Maldives include nearly 1,200 islands in 15 major atolls spanning approximately 470 miles to just south of the equator. Malé is the only commercially developed island. It is home to 70,000 residents within an area of about one-half square mile.