Scientists propose El Niño network in Indian Ocean

November 15, 2000

Australia, India and Malaysia could benefit significantly from the development of a multi-million dollar observing system in the Indian Ocean that could identify climate signals similar to El Niño climate signals in the southern Pacific Ocean, say researchers.

University of Colorado at Boulder Professor Peter Webster, one of several scientists worldwide who is spearheading studies of the Indian monsoon system, said the network could indicate changes in regional rainfall months in advance and positively impact the lives of almost two-thirds of the world's population.

"During the last two years we have discovered that there are modes of variability in the Indian Ocean similar to the El Niño phenomena," said Webster, director of CU-Boulder's Program in Atmospheric and Oceanic Sciences. "We are now starting to use this understanding for the prediction of climate variability in the Indian Ocean."

Since more than half of the world's population resides around the Indian Ocean rim in essentially agrarian societies, the prediction of climate variability is crucial in helping people in those regions maintain sustainable crop development, he said.

Webster and Professor Sulochana Gadjil of the Indian Centre for Atmospheric and Ocean Sciences and the Indian Institute of Science each gave keynote presentations on the topic at the Perth Oceans and Climate 2000 Conference. The conference was held in Perth, Australia, Nov. 10 to Nov. 14.

Both scientists called for international support in creating an ocean-wide observation network of moored and drifting instruments in the tropical Indian Ocean. The network would be similar to the existing array of mooring instruments in the Pacific Ocean, which was used to predict massive changes in ocean conditions leading up to the last major El Niño event in 1997.

India's Department of Ocean Development has established a regional trial network of meteorological ocean buoys, which will be complemented by a series of drifting floats similar to those deployed by the Australian Commonwealth Scientific and Industrial Research Organization, or CSIRO, in the Indian Ocean northwest of Australia.

"In the Indian Ocean, the network could help predict the strength of key rainfall events -- such as the Indian monsoon -- which govern sustainability in Indian food production and influence winter rainfall across southern Australia," Webster said. More than 60 percent of Indians depend on agriculture for their livelihoods, and there has been widespread concern in recent years over decreased crop production there, he said.

"There are large fluctuations in the annual food-grain production in response to the variability of the monsoon," said Gadjil. "Sustained observations of the critical atmospheric and oceanic variables over the equatorial Indian Ocean is an essential prerequisite to understanding the development of cloud build-up and large-scale monsoon rainfall."

Gadjil discovered that the monsoon is maintained by the northward movement of clouding over the equatorial Indian Ocean. She has been involved in an Indian observational experiment on the Bay of Bengal since 1999.

Webster, who has led international oceanographic research cruises in the Indian Ocean involving Australian and American researchers, said the way the upper ocean and atmosphere interact is the best indicator for predicting variations in rainfall and climate. "There seems to be a strong connection between processes occurring in the upper 100 meters of the Indian Ocean and, for example, how much winter rain falls in southern Australia, he said.

In 1999 Webster discovered a series of currents in the Indian Ocean linked to a basin-wide shift in sea temperatures, winds and rain. Known as the "Indian Ocean Dipole," it affects the frequency of storm systems.

Earlier this year, CSIRO Chief Nan Bray called for the evaluation of a climate observing system that could indicate changes for regional rainfall months ahead. "We think the Indian Ocean effects are predictable because ocean currents are involved, and currents are more predictable than weather," said Bray. "Improved climate prediction for the nations around the Indian Ocean would impact the lives of almost two-thirds of the world's population."
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Nearly 100 scientists from 10 countries participated in the Oceans and Climate 2000 workshop on Sustained Observations of Climate in the Indian Ocean at the recent ocean conference in Perth. The workshop was sponsored by the Intergovernmental Oceanographic Commission of UNESCO, the West Australian government, Australia's Federal Department of Industry, Science and Technology and CSIRO. Contact:

University of Colorado at Boulder

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