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Rob Gutro               May 1, 2003
Goddard Space Flight Center
(Phone: 301-286-4044)
Rgutro{at}pop900.gsfc.nasa.gov

Chip Rose
University of Maryland-Baltimore County
(Phone: 410-455-5793)
Crose{at}umbc.edu

Harvey Leifert
American Geophysical Union
(Phone: 202/777-7507)
hleifert{at}agu.org

RELEASE NO. 03-44

NASA DISCOVERS A SOGGY SECRET OF EL NINO

NASA-funded researchers have discovered El Nino's soggy secret. When
scientists identified rain patterns in the Pacific Ocean, they
discovered the secret of how El Nino moves rainfall around the globe
during the life of these periodic climate events when waters warm in
the eastern Pacific Ocean.

The results may help scientists improve rainfall forecasts around the
globe during the life of an El Nino, and may also offer new insights
into how an El Nino develops.

The findings were highlighted in a paper authored by Scott Curtis of
the University of Maryland - Baltimore County, Baltimore, Md., and
Bob Adler, of Goddard Space Flight Center, Greenbelt, Md. The study
appeared in a recent issue of the American Geophysical Union's
Journal of Geophysical Research.

In an effort to predict and understand the effects of El Nino, most
scientists focus on seasonal changes in rainfall patterns, like where
and when rain falls during winter. This study takes a different
approach by first looking at the evolution of rainfall over the
geographic area of the Pacific, which has the power to change the
global winds and re-direct rainfall patterns around the world.

Curtis and Adler found a significant pattern of alternating rainfall
for El Ninos since 1979, with wetness in eastern China, dryness over
Indonesia and wetness in the south Indian Ocean and Australia.

They noted that this pattern swings eastward as the El Nino weakens.
As El Nino weakens, rainfall patterns alternate from one area to
another. In the eastern Pacific, there is wetness on the Equator,
dryness off the coast of Mexico, and wetness off the coast of
California. The traditional view of El Nino based on seasonal
rainfall patterns obscures these relationships.

El Nino events, like individual thunderstorms, differ in intensity,
lifespan, rainfall, and other characteristics, making them difficult
to quantify. So, Curtis and Adler had to set parameters to define El
Ninos based on rainfall that occurs in the equatorial Pacific. They
looked at the periods before rainfall began, when the El Nino
started, peaked, faded, and after it ended. They also identified
areas around the globe that were consistently wet or dry during each
El Nino evolution stage.

Curtis and Adler utilized global rainfall datasets developed from
satellites and rain gauges from all over the world, which are part of
the Global Precipitation Climatology Project under the Global Energy
and Water Cycle Experiment (GEWEX), a project heavily supported by
NASA.

Data from the Tropical Rainfall Measuring Mission (TRMM) satellite,
used in this study, will also help ensure the accuracy of satellites
used by the National Oceanic and Atmospheric Administration (NOAA)
and Department of Defense. TRMM is a joint NASA/Japanese Space Agency
mission to study tropical rainfall and its implications for climate.
Each day, the TRMM spacecraft observes the Earth's equatorial and
tropical regions.

In the future this kind of study will help pinpoint where an El Nino
will generate floods, droughts, and changes in rainfall around the
globe. This information will be extremely useful once NASA's Global
Precipitation Measurement mission, currently in formulation launches
sometime after 2007.

This NASA funded work addresses a number of NASA's Earth Science
Enterprise research strategies, including how variations in local
weather, precipitation and water resources are related to global
climate variation, in this case caused by El Nino. By recognizing
global rainfall patterns associated with El Nino and by better
understanding the impacts of El Nino, researchers may be able to
better understand and predict these climate variations.

For more information and images on the Internet, visit:
http://www.gsfc.nasa.gov/topstory/2003/0428soggyNino.html

For information the about various programs mentioned above on the
Internet, visit:
El Nino events:
http://www.elNino.noaa.gov/edu.html

GEWEX:
http://www.gewex.org/

Global Precipitation Measurement mission:
http://gpm.gsfc.nasa.gov/

TRMM:
http://trmm.gsfc.nasa.gov

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*****************************
Mark S. Hess
Chief, Office of Public Affairs
NASA/GSFC, Code 130
E-Mail:  Mark.S.Hess{at}nasa.gov
Phone:  301 286-6255
Fax:  301 286-1707
*************

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