Team finds new way to identify which El Nino events will have biggest impact on U.S. winter weather

Feb 08, 2013
El Niño, warmer than average waters in the Eastern equatorial Pacific (shown in orange on the map), affects weather around the world. A new study, just published in the February 2013 issue of the Journal of Climate, describes an atmospheric El Niño signal that is very strongly associated with U.S. winter weather impacts. Credit: NOAA Visualization Lab

(Phys.org)—Weather forecasters have long known that El Niño events can throw seasonal climate patterns off kilter, particularly during winter months. Now, new research from NOAA and the University of Washington suggests that a different way to detect El Niño could help forecasters predict the unusual weather it causes.

A network of buoys that spans the Pacific, the TAO-Triton array, observes conditions in the upper ocean and is essential for forecasting El Niño months in advance, and for monitoring it as it grows and decays. A new study, just published in the February issue of the Journal of Climate, describes an atmospheric El Niño signal that is very strongly associated with U.S. impacts. Ed Harrison, Ph.D. of the NOAA Pacific Marine Environmental Laboratory in Seattle and Andrew Chiodi, Ph.D., of the NOAA Joint Institute for the Study of the Atmosphere and Ocean at the University of Washington, co-authored the paper.

"When it comes to El Niño's , we are always looking for ways to improve our forecasting skill," said Harrison. "Our goal is to extract the most useful information to predict El Niño seasonal weather anomalies."

Harrison and Chiodi looked at all El Niño events that were identified by measurements since 1979. They then examined for these events and found that a subset of the events showed a sharp dip in heat radiating from the tops of deep convective clouds, an indicator known as outgoing long-wave radiation or OLR. When comparing the El Niño events to historical weather records, the scientists found that the El Niño events with drops in OLR were the ones most likely to play havoc with winter weather.

They also found that El Niño events with no corresponding drop in OLR did not produce statistically significant anomalies in . The dip in heat from deep usually occurred before winter, so the timing of the signal could help forecasters improve winter seasonal outlooks, the scientists said.

"By sorting El Niño events into two categories, one with OLR changes and one without, forecasters may be able to produce winter seasonal outlooks with more confidence than previously thought possible," Harrison said.

El Niño refers to a warming of waters along the equator in the Eastern Pacific Ocean. Through its influence on the atmosphere, El Niño shifts tropical rainfall patterns which causes further shifts in weather around the globe, including milder winters in western Canada and parts of the northern United States and wetter winters in the some southern states.

Industry sectors from energy and construction to transportation and tourism are keenly interested in how El Niño will affect their costs. El Niño-influenced weather can affect fuel oil demand, travel delays, and retail sales. Better accuracy in El Niño predictions could help industry to prepare for its impacts more efficiently.

Explore further: Fiction prepares us for a world changed by global warming

More information: journals.ametsoc.org/doi/abs/10.1175/JCLI-D-12-00097.1

add to favorites email to friend print save as pdf

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 ...

El Nino phenomenon to die out by mid-year

Mar 30, 2010

Weather experts said Tuesday that El Nino, the weather anomaly that wreaks havoc around the Pacific and east Africa, has peaked and would disappear by mid-year.

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 ...

Recommended for you

Drought may take toll on Congo rainforest, study finds

13 hours ago

(Phys.org) —A new analysis of NASA satellite data shows Africa's Congo rainforest, the second-largest tropical rainforest in the world, has undergone a large-scale decline in greenness over the past decade.

User comments : 0

More news stories

On global warming, settled science and George Brandis

The Australian Attorney General, Senator George Brandis is no stranger to controversy. His statement in parliament that "people do have a right to be bigots" rapidly gained him notoriety, and it isn't hard to understand why ...

When things get glassy, molecules go fractal

Colorful church windows, beads on a necklace and many of our favorite plastics share something in common—they all belong to a state of matter known as glasses. School children learn the difference between ...

FCC to propose pay-for-priority Internet standards

The Federal Communications Commission is set to propose new open Internet rules that would allow content companies to pay for faster delivery over the so-called "last mile" connection to people's homes.