February 23, 2010

Indian Ocean Provides Clues To El Nino

Researchers are tracking Indian Ocean climate patterns with the possibility that they will improve early-warning systems for the El Nino phenomenon, which could save countless lives and billions of dollars lost each year to the severe weather it causes.

Researchers from Japan and France said their new forecast model may predict an El Nino up to 14 months ahead of time, several months earlier than with current models. A paper on the project was published in the journal Nature Geoscience.

"It is important because...this helps to improve El Nino forecasts. It can save a lot of money for agriculture," lead researcher Takeshi Izumo at the Research Institute for Global Change in Yokohama, Japan, said in a telephone interview with Reuters.

The El Nino phenomenon is responsible for wreaking havoc such as floods, droughts, and severe weather systems. Developing countries that are dependent on agriculture and fishing are most badly affected, though the 1997-98 El Nino cost the United States nearly $25 billion, according to the NOAA.

The Indian Ocean Dipole (IOD), the equivalent of an El Nino in the Indian Ocean, had a role in causing the phenomenon, Izumo and his colleagues discovered. "IOD strongly influences the triggering of El Nino (the following year). In this study, we did a simple forecast model, we included the IOD index and we can have a very good forecast for the El Nino in the next year," Izumo said.

The team said they found a missing piece of the puzzle for triggering an El Nino. "We showed here that in addition to the usual causal factor, which is that of warm water volume recharge, there is the IOD which is a very important causal factor for El Nino development," he added.

If scientists and weather forecasters have an accurate and early prediction system for an El Nino, they could help lessen the destruction caused by the phenomenon. "El Nino forecasting is important for disaster prevention and impact management, and helps to reduce El Nino-related losses," Izumo said.

The 1997 El Nino was responsible for a severe drought that struck Indonesia, which in turn caused many fires. Better forecasting models could have played a role in preventing many of those fires.

An El Nino is followed by a cold phase, called a La Nina, which usually occurs the following year.


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