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2009-10 El Nino near certain: new kind of El Nino hurricane threat discovered
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El Niño years typically result in fewer hurricanes forming in the Atlantic Ocean. But a new study suggests that the form of El Niño may be changing potentially causing not only a greater number of hurricanes than in average years, but also a greater chance of hurricanes making landfall, according to climatologists at the Georgia Institute of Technology. The study appears in the July 3, 2009 edition of the journal Science as reported by the Georgia Tech News Service and ScienceDaily.
“Normally, El Niño results in diminished hurricanes in the Atlantic, but this new type is resulting in a greater number of hurricanes with greater frequency and more potential to make landfall,” said Peter Webster, professor at Georgia Tech’s School of Earth and Atmospheric Sciences.
That’s because this new type of El Niño, known as El Niño Modoki (from the Japanese meaning “similar, but different”), forms in the Central Pacific, rather than the Eastern Pacific as the typical El Niño event does. Warming in the Central Pacific is associated with a higher storm frequency and a greater potential for making landfall along the Gulf coast and the coast of Central America.
Even though the oceanic circulation pattern of warm water known as El Niño forms in the Pacific, it affects the circulation patterns across the globe, changing the number of hurricanes in the Atlantic. This regular type of El Niño (from the Spanish meaning “little boy” or “Christ child”) is more difficult to forecast, with predictions of the December circulation pattern not coming until May. At first glance, that may seem like plenty of time. However, the summer before El Niño occurs, the storm patterns change, meaning that predictions of El Niño come only one month before the start of hurricane season in June. But El Niño Modoki follows a different prediction pattern.
“This new type of El Niño is more predictable,” said Webster. “We’re not sure why, but this could mean that we get greater warning of hurricanes, probably by a number of months.”
As to why the form of El Niño is changing to El Niño Modoki, that’s not entirely clear yet, said Webster.
“This could be part of a natural oscillation of El Niño,” he said. “Or it could be El Niño’s response to a warming atmosphere. There are hints that the trade winds of the Pacific have become weaker with time and this may lead to the warming occurring further to the west. We need more data before we know for sure.”
In the study, Webster, along with Earth and Atmospheric Sciences Chair Judy Curry and research scientist Hye-Mi Kim used satellite data along with historical tropical storm records and climate models.
The research team is currently looking at La Niña, the cooling of the surface waters in the Eastern and Central Pacific.
"In the past, La Nina has been associated with a greater than average number of North Atlantic hurricanes and La Nina seems to be changing its structure as well,” said Webster. “We’re vitally interested in understanding why El Niño-L Niña has changed. To determine this we need to run a series of numerical experiments with climate models.”
(Reuters) - An El Nino weather pattern this year appears almost certain, Australia's Bureau of Meteorology said in a revised forecast, raising the prospect of drought in Australia and a even weaker monsoon in India.
The odds for El Nino, an abnormal warming of the eastern Pacific Ocean that creates havoc in weather patterns across the Asia-Pacific region, had risen significantly since two weeks ago, when the bureau said there was a more than 50 percent chance.
"El Nino is a little bit like recession, you are in it before you can say you have one. If it continues as it is now, the historians will say the El Nino started in May," said David Jones, head of the bureau's climate analysis, told Reuters.
He said they could declare a full El Nino within weeks.
That's probably bad news for farmers in Australia who have sown near record acreage, and in India, which is already bracing for below-average monsoon rains, the lifeblood of the country's agriculture.
It would also have implications for commodity markets, potentially lifting wheat prices that have slumped over the past month on expectations of a bumper global harvest, and adding further fuel to soaring sugar prices that are already bracing for a second disappointing crop year from top consumer India.
Most of Australia's 2009/10 wheat crop has been planted following plentiful rain, leading to forecasts of a harvest of as much as 23 million tons, the best since 2005/06 when 25.2 million tons were harvested.
"The growers I speak to say if we were to get some rains in spring we could get above average yields. But if the El Nino forecast materialized, we are again at risk of having a sub-standard crop," said Richard Koch, managing director of farm advisory firm Profarmer.
Australia's grain production is still recovering from the worst drought in more than 100 years that cut the annual wheat harvest to as little as 10.6 million tons in 2006/07.
India's weather office last week cut its forecast for the June-September monsoon rains by 3 percentage points to 93 percent of normal, after four years of above average rainfall. From June 1 to June 24 rains were 54 percent below normal.
A severe El Nino spawns searing drought in countries in southeast Asia, harming rubber production, while causing heavy flooding in Peru, Ecuador and Chile, among others.
The bureau's latest report found that the eastern Pacific Ocean was continuing to warm, with sea temperatures one degree Celsius above normal, and trade winds were continuing to weaken. They see little chance of avoiding an El Nino.
The Southern Oscillation Index (SOI), calculated from monthly and seasonal fluctuations in air pressure between Tahiti and Darwin, remained at around negative 2, while the monthly value for May was negative 5.
A sustained negative SOI often indicates El Nino.
"A more complete picture of the situation in the Pacific will be available next week when the final June indices are calculated.”
The Climate Prediction Center in the United States said in June that conditions were favorable for a switch to El Nino conditions during June to August. Reported by Bruce Hextall and Michael Perry in Sydney.
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