Title  : PRELIMINARY RESULTS OF RESEARCH ON EL NINO REPORTED AT AGU FALL
         MEETING
Type   : Press Release
NSF Org: OD / LPA
Date   : December 3, 1993
File   : pr9391x



Cheryl Dybas                                                                  
December 3, 1993 (202) 357-9498                                                 
                    NSF PR 93-91

PRELIMINARY RESULTS OF RESEARCH ON EL NINO REPORTED AT AGU FALL MEETING

     In order to study the strong air-sea interaction occurring in the
"warm pool" in the western equatorial Pacific Ocean -- which is
responsible for the climate phenomenon called El Nino -- the TOGA
(Tropical Ocean Global Atmosphere) Coupled Ocean-Atmosphere Response
Experiment (COARE), was conducted between November 1992 and February
1993.  A striking finding of this National Science Foundation-funded
research program was that a significant fraction of the heavy rainfall
over the warm pool occurs from shallow clouds; this observation of
so-called "warm rain" has important implications for modeling the
atmosphere's response to cloud formation and precipitation.  Results of
the research will be presented at the American Geophysical Union fall
meeting in San Francisco from December 6-10. The large range of
atmospheric and oceanic conditions which were observed during COARE
confirm previous hypotheses about the role of air-sea interaction in the
warm pool system, and also provide an excellent database for future
model development.  Observations were made which are being used to
directly and indirectly estimate the exchange of heat, moisture, and
momentum between the atmosphere and ocean, with the objective of
improving scientists' ability to model and predict the evolution of the
warm pool system.  Observations from COARE show that heavy rainfall
events are responsible for salinity changes in the ocean which
substantially modify upper ocean mixing, and thus heat and momentum
exchanges.  This is important for improvements to future predictions of
the El Nino phenomenon, among other climate variations, where east-west
displacements of the warm pool system play an important role.

     Leading up to the COARE experiment, El Nino conditions in the
tropical Pacific were near normal, with slightly cold ocean conditions
developing in the eastern equatorial Pacific.  This led some El Nino
forecast models to predict the development of a cold event during early
1993.  However, the warm conditions returned in 1993, associated with an
eastward migration of the warm pool system.  TOGA COARE was conducted
during the re-development of the El Nino, allowing an unprecedented
sampling of the conditions in the western Pacific which may have led to
this re-intensification.  Scientists hope that these observations will
help them understand why the model predictions failed, according to
researcher Roger Lukas of the University of Hawaii.

     Pioneering observations of oceanic rainfall were made using Doppler
weather radar on ships and on research aircraft.  These observations
provide the very elusive areal averages of precipitation needed to
compute freshwater exchange between the ocean and atmosphere, as well as
the detailed motions inside atmospheric systems.

-end-

     The National Science Foundation is an independent agency of the
federal government established in 1950 to promote and advance scientific
progress in the United States.  NSF accomplishes its mission primarily
by competitively awarding grants to educational institutions for
research and education in the sciences, mathematics, and engineering.


     This and other information is available electronically on STIS,
NSF's Science and Technology Information System.  For more information
about STIS contact the Publications Section at (202) 357-7861 and
request the "STIS Flyer," NSF Publication #91-10, or send an E-mail
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