[cfgeeks] El Nino more like Los Ninos, weather study finds

[Kevin Inscoe]

El Nino more like Los Ninos, weather study finds
   Posted by: "Kim Noyes" kimnoyes at gmail.com noyeskim
   Date: Thu Jul 2, 2009 8:46 pm ((PDT))

 El Nino more like Los Ninos, weather study finds
 The Pacific Ocean warming can be broken down into two distinct patterns,
Georgia Institute of Technology researchers say. The finding could help
improve North Atlantic Hurricane predictions.
By Shara and Yurkiewicz
4:59 PM PDT, July 2, 2009
 El Nino, the seasonal Pacific Ocean warming that affects the world's
weather, may not be just one little boy -- it seems to be two little boys.

Two distinct patterns of warming occur in the Pacific Ocean, according to
researchers at the Georgia Institute of Technology in Atlanta, and their
frequencies have been changing in recent decades.

 Tracking one of these two events could yield earlier, more-accurate
predictions of seasonal North Atlantic hurricanes.

The periodic warming (El Nino) and cooling (La Nina) of the eastern
equatorial Pacific Ocean is known as the El Nino Southern Oscillation and
affects global weather patterns.

El Nino, which occurs about every three to five years, is an ocean warming
that begins in the early summer months and that reaches its peak in
December.

The event can bring droughts to Australia, flooding in the Southern U.S. and
Peru, changes in the Indian summer monsoon, and fewer North Atlantic
hurricanes.

But after poring over more than half a century's worth of atmospheric and
oceanic data collected by national and international centers, the Georgia
Tech researchers concluded that there are in fact two forms of Pacific Ocean
warming, and that these have different effects on the frequency and paths of
North Atlantic hurricanes.

One form, eastern Pacific warming, correlates with hurricane activity
identical to that of the conventional El Nino.

The other form, central Pacific warming, is associated with enhanced
hurricane activity on the Eastern Seaboard of the U.S. and eastern Mexico.

"Apparently, El Nino comes in two flavors," commented Kerry Emanuel, a
professor of atmospheric science at MIT who was not associated with the
study. Knowing that these two independent modes have different effects could
factor into predictions of Atlantic hurricanes, he added.

By tracking the second pattern, instead of just focusing on El Nino as a
whole, "we may know what the character of the hurricane family in the next
season will look like," said coauthor Peter Webster, professor of earth and
atmospheric sciences at Georgia Tech.

North Atlantic hurricanes affect the U.S. Gulf Coast, Middle America and the
Caribbean, and can cause billions of dollars in damage in the U.S. alone.

Current hurricane forecasting efforts use El Nino as a whole to predict the
number and frequency of hurricanes that will occur in the summer and fall.
But these predictions cannot be made before June.

"In May, the Pacific Ocean is trying to decide whether to have an El Nino, a
La Nina, or remain neutral," Webster said.

The study's findings, to be published Friday in the journal Science, could
help provide a few extra months of lead time. That's because the central
Pacific warming starts its annual cycle slightly earlier than the eastern
pattern. This would help the insurance industry, which now must lock in its
annual rates before the Pacific activities become clear.

The scientists also found that the central Pacific warming events have
increased in frequency over the last few decades: 80% of them in the last 60
years have occurred since 1990. At the same time, the eastern Pacific
warming events have declined.

Nobody knows why, Webster said. It could be temporary, associated with
natural oceanic or atmospheric oscillations, he added. But it is also
possible that increasing sea surface temperatures associated with global
warming may be causing the shift by triggering changes in trade wind
patterns.

"The nature of El Nino is changing, and there are lots of subtleties,"
Webster said. "We want to predict those variations in El Nino and work out
what the implications are of this new type of Pacific Ocean warming."

Source:
http://www.latimes.com/news/nationworld/nation/la-sci-weather4-2009jul04,0,5854766.story


-- 
Kevin P. Inscoe        Amateur Call Sign: KE3VIN
Deltona, FL 32738          28.9497N by 81.1952W
kevin [at] inscoe [dot] org  http://kevininscoe.com
Skype: ke3vin
"Write to be understood, speak to be heard, read to grow." - Lawrence
Clark Powell