Research yields key to better predictions of El Nino

Jun 27, 2012 By Lee Tune

(Phys.org) -- A University of Maryland scientist and an undergraduate Indian student he mentored in India have uncovered a major new finding about El Nino -- the cyclical climate event that appears every 2-7 years, sometimes with major global weather impacts such as massive flooding in some regions and severe droughts in others and resulting major economic impacts.

Just published in Nature Climate Change, their research reveals a previously unrecognized sign of a looming that can be detected up to 18 months in advance, nine months earlier than current forecasting models allow. Raghu Murtugudde, a UMD professor of atmospheric and , and Nandini Ramesh, who was an undergraduate student at the Divecha Centre for Climate Change, Indian Institute of Science in Bangalore India when this research was performed, say their new clue to the beginning of an El Nino lies in the discharge of massive volumes of sub-surface warm water from the equatorial western Pacific Ocean north of Australia.

"Our new study shows that during the time between two El Ninos warm waters accumulate below the surface at that point in the Pacific and then begin to discharge towards the west nearly 18 months before the December-January appearance of a new El Nino when surface warming occurs at the International Dateline [the imaginary line that separates two consecutive calendar days and sits on the 180 deg. line of longitude in the middle of the Pacific Ocean]," says Murtugudde.

"We found that this immaculate conception of El Nino with a gestation period of 18 months remains identical for all flavors [types] of El Nino and appears to be the most fundamental process that drives El Ninos," he says. Scientists have known for four decades that El Nino events appear when waters in the tropical eastern Pacific start to warm up. However researchers have struggled to understand the early steps in this process even as they have watched three significant shifts, or , in El Ninos during the past 40 years, with the latest occurring since 2000. This newest flavor of El Nino has its warmest waters in the central-equatorial Pacific Ocean near the International dateline, rather than in the eastern-equatorial Pacific. Recent research suggests these El Ninos appear to be becoming more common and progressively stronger, and many scientists think this shift is a consequence of global warming.

"We know that to see the future for a how a particular El Nino will develop, you have to look below the surface," says Michael McPhaden, a Seattle-based scientist with the National Oceanic and Atmospheric Administration, who has been called "Mr. El Nino". "This study emphasizes that whatever flavor of El Nino we may encounter -- and there appear to be more than one -- the key to understanding and predicting El Nino is to continuously measure the cold, dark, and remote interior of the tropical Pacific Ocean. At face value, its paradoxical that to anticipate the rains (or lack thereof) in Texas, you have to look months earlier at temperatures 300 feet below the surface of the Pacific 10,000 miles away. Nature is that way though," says McPhaden, who oversees an array of Pacific Ocean monitors that send real-time readings used for monitoring, understanding and forecasting El Nino and La Nina.

The new findings by Ramesh and Murtugudde were published online on June 24 in the journal Nature Climate Change. The work was conducted by Ramesh under Murtugudde's close guidance while both were at the Divecha Centre for of the Indian Institute of Science, she as an undergraduate student and he as a visiting professor on sabbatical from UMD. For this study, they examined El Nino events from1958 through 2011 to try to identify any climate factors present in all of them. They found that although not all El Nino events follow the same course, they all begin with a discharge of massive volumes of sub-surface warm water from the equatorial western Pacific.

"This is an exciting result that provides a new paradigm for understanding and predicting El Ninos and for understanding the impact of global warming on El Ninos," says Murtugudde. "It has the potential for offering a way forward to predict El Nino with a significant lead time of over a year and also provides a caution against simple models that use statistical approaches of surface expressions of El Nino to make El Nino predictions." Further research, he adds, is clearly needed to understand what processes are responsible for initiating the warm water discharge below the surface so far in advance of the mature phase of the El Nino.

The El Nino Southern Oscillation

The El Nino Southern Oscillation, (ENSO) as it is known by scientists, is the fluctuation in sea-surface temperatures over the tropical . When these waters are cooler than average, like this past winter, it is known as La Nina. When these waters are warmer than average, we are in the El Nino phase of the cycle. When the waters are near average, the condition is considered to be a neutral phase.

Surface water temperature changes over world's largest body of water have a profound effect on weather patterns around the globe, by causing a shift in the strength and position of the storm tracks around the Earth. The U.S. Climate Prediction Center recently gave a 50 percent chance that El Nino conditions will develop during the second half of 2012. These new UMD-led findings could allow future predictions to become more accurate and provide much longer advance warning.

Explore further: Hurricane Edouard right environment for drone test (Update)

Related Stories

Forecasters say El Nino may be developing

Jun 08, 2009

(AP) -- A new El Nino could be approaching. Sea-surface temperatures have been warming in the tropical Pacific Ocean, suggesting the potential for the development of the El Nino climate phenomenon this summer, according ...

Changing El Nino could reshape Pacific Ocean biology

Jun 15, 2012

Over the past few decades, the scientific understanding of El Nino has grown increasingly complex. Traditionally viewed as a periodic warming focused largely in the eastern equatorial Pacific Ocean, El Nino is associated ...

El Nino To Affect Weather In Colorado And Western U.S.

Dec 01, 2006

Colorado's late fall snowstorms could disappear by mid-December due to the influence of an El Niño event in the tropical Pacific Ocean, said Klaus Wolter, a University of Colorado at Boulder and National Oceanic and Atmospheric ...

Warm temps, El Nino delay lakes' freezing

Jan 12, 2007

A strong El Nino and warmer temperatures pushed back lake freeze dates for the Northeast and Midwest areas of the United States, a water scientist said.

El Nino may, or may not, soak California

Dec 15, 2006

El Nino, the periodic warming of Pacific waters, puzzles meteorologists who said they don't know whether it will bring needed rain to Southern California.

Recommended for you

Tree rings and arroyos

3 hours ago

A new GSA Bulletin study uses tree rings to document arroyo evolution along the lower Rio Puerco and Chaco Wash in northern New Mexico, USA. By determining burial dates in tree rings from salt cedar and wi ...

NASA image: Agricultural fires in the Ukraine

5 hours ago

Numerous fires (marked with red dots) are burning in Eastern Europe, likely as a result of regional agricultural practices. The body of water at the lower left of this true-color Moderate Resolution Imaging ...

NASA marks Polo for a hurricane

5 hours ago

Hurricane Polo still appears rounded in imagery from NOAA's GOES-West satellite, but forecasters at the National Hurricane Center expect that to change.

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

Roland
not rated yet Jun 27, 2012
This article is confusing. "equatorial western Pacific Ocean north of Australia." Huh? North of AU is the Arafura Sea, but it isn't equatorial. Are they talking about the Caroline Basin? If so, why don't they say "north of New Guinea" ? Then they talk about the dateline, which is 40deg(~2500mi) east of there. Does the warm water move west, or east?