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ShareApr. 26, 1999 — An international team led by the University of Colorado at Boulder will begin a research effort in the Indian Ocean April 26 to study the South Asian summer monsoon, which has been shown to affect weather patterns as far away as the United States.
Peter Webster, director of CU-Boulder's Program in Atmospheric and Oceanic Sciences who is directing the massive project, said the team will be studying the upper 400 meters of the ocean and its interaction with the overlying atmosphere. "Studies on the coupling of the ocean and atmosphere should provide new clues in predicting the summer monsoon and its variability," he said.
The $2 million effort, known as the Joint Air-Sea Monsoon Interaction Experiment, or JASMINE, is a joint venture of CU-Boulder, the University of Washington, the University of Hawaii, the National Oceanic and Atmospheric Administration, the National Science Foundation, NASA and several Australian agencies.
"Roughly 65 percent of the world's population lives in monsoon regions," said Webster. "This is the fastest growing region on the planet. By the year 2025, it is anticipated this number will grow to 75 percent."
Data indicate the last Indian monsoon impacted the behavior of El Niño and subsequent weather patterns in the United States, said Webster. "Our primary goal is to understand the basic physics that underpin these variations in the Indian Ocean monsoons and eventually allow us to predict them so that the people of the region will have warning some months in advance of drought or floods."
The six-week expedition will be aboard the NOAA Ship, Ron Brown, and will take place in the Bay of Bengal in the northeast Indian Ocean between April 26 and June 6, he said.
Variability of South Asian monsoons occurs on time scales of 20 days to 40 days, Webster said. They can change from strong periods of precipitation to severe droughts that affect agrarian populations in the region, he said.
"It is the variability on these time scales that really impact agriculture and society," Webster said. Other monsoon systems significantly affect the climates of Asia, Africa and Australia.
The strength of the summer monsoon is influenced by the El Niño-Southern Oscillation System, or ENSO, which takes place in the Pacific Basin, said Webster. Marked by periodic changes in the equator's atmospheric mass and pressure every two to 10 years, the Southern Oscillation triggers El Niño's signature movement of warm water from the western Pacific eastward that raises ocean temperatures.
Because of its interplay with ENSO, the annual Indian monsoon season frequently disrupts climate worldwide, from droughts in Australia and Indonesia to heavy rainfall and flooding over the coast of South America and the southeastern United States.
Webster co-directed a massive research effort known as the TOGA-COARE program that involved more than 1,000 scientists, technicians and students from 20 nations from 1991 to 1994 to better understand the ocean-atmosphere interactions in the tropical Pacific.
That study indicated heavy rains from systems ranging from small, warm clouds to large weather disturbances created a freshwater "lens" of water on the surface of the Pacific northeast of Australia, inhibiting mixing with the underlying saltwater as it expanded eastward across the Pacific during El Niño.
"This fresh layer of water is the main reason the tropical Pacific remains so warm during these periods," he said.
Roughly twice the size of the United States, the warm pool of water off the Australian coast is known as Earth's "boiler box" because of its influence on worldwide weather.
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