A research campaign in the Indian Ocean indicates there are ocean-atmosphere interactions similar to El Niño events in the Pacific, but are not always tied to El Niño as previously had been believed by climate researchers.

Peter Webster, director of the University of Colorado at Boulder's Program in Atmospheric and Oceanic Sciences, or PAOS, who is directing the project, said the 1997 to 1999 findings were somewhat surprising. "Our research indicates the Indian Ocean has it's own El Niño -like phenomenon characterized by an east to west oscillation of warm waters that affect other parts of the world," said Webster.

During 16 of the years from 1950 to 1998, the equatorial sea-surface temperature gradients reversed -- much like El Niño -- substantially warming the western portion of the Indian Ocean. But only three of the years were active El Niño years, he said.

Although the Indian Ocean's summer monsoon was strongly linked to the El Niño/Southern Oscillation system, or ENSO, from 1960 to 1988, there has been no significant link since that time, said Webster. ENSO triggers movement of warm water from the western Pacific eastward every two to 10 years, wreaking havoc on the environment through the proliferation of droughts and floods worldwide.

A paper on the subject by Webster, Andrew Moore and Johannes Loschnigg from CU-Boulder's PAOS and Robert Leben from CU-Boulder's aerospace engineering department was published in the Sept. 23 issue of Nature.

In 1997 and 1998 the Indian Ocean monsoon triggered the wettest year on record in East Africa, sparking an outbreak of mosquito-borne Rift Valley Fever and associated cholera and malaria in livestock and people. "This event occurred completely independent of El Niño activity," said Webster.

"I think people have become a bit 'El Niñocentric,'" he said. "Certainly El Niño plays a major role in climate variation on Earth, but t
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Contact: Peter Webster
Peter.Webster@colorado.edu
303-492-6344
University of Colorado at Boulder
22-Sep-1999