Jacques van Oene
November 9th 04, 02:31 PM
Gretchen Cook-Anderson
Headquarters, Washington Nov. 8, 2004
(Phone: 202/358-0836)
Rob Gutro
Goddard Space Flight Center, Greenbelt, Md.
(Phone: 301/286-4044)
RELEASE: 04-369
TRMM SATELLITE PROVES EL NINO HOLDS THE REINS ON GLOBAL RAINS
NASA scientists recently found the El Nino Southern
Oscillation (ENSO) is the main driver of the change in rain
patterns all around the world.
The NASA and Japan Aerospace Exploration Agency (JAXA)
Tropical Rainfall Measuring Mission (TRMM) satellite has
enabled scientists to look around the globe and determine
where the year-to-year changes in rainfall are greatest. The
TRMM is a joint mission between NASA and JAXA designed to
monitor and study tropical rainfall.
Researchers Ziad Haddad and Jonathan Meagher of NASA's Jet
Propulsion Laboratory, Pasadena, Calif., Robert Adler and
Eric Smith of NASA's Goddard Space Flight Center, Greenbelt,
Md., used TRMM data to identify areas where the year-to-year
change in rainfall between 1998 and 2003 was greatest.
By studying the rain patterns in these areas over the past 50
years, with rain gauge data prior to 1998, they established
the main component of this change in global rainfall is
directly correlated with the El Nino Southern Oscillation.
The study appeared in a recent issue of the Journal of
Geophysical Research-Atmospheres.
Haddad and his colleagues compared local changes in worldwide
rainfall. For years, scientists have known El Nino
drastically modifies rainfall patterns in many regions. For
example, Indonesia and the Northeastern Amazon basin
consistently suffer droughts during El Nino and excessive
rains during La Nina. The Southeastern United States and
California are typically wetter than usual during El Nino and
drier than usual during La Nina.
Scientists also have known several regions with abundant rain
are not influenced by the El-Nino/La-Nina changes, including
the Bay of Bengal and the vast expanse of the Western Pacific
Ocean between the Marshall Islands, Micronesia and the
Marianas.
Until the launch of TRMM in 1997, it was impossible to
accurately measure change in tropical rainfall patterns,
because no instruments were available to record global
rainfall. TRMM uses microwave technology to probe through
clouds and estimate how much rainfall they are producing. The
TRMM data are invaluable over areas where there are no rain
gauges, such as the open ocean.
Using TRMM's measurements, the researchers were able to
condense the year-to-year change in rainfall patterns into a
single rain-change index. The index is a color-coded map that
shows areas of rainfall around the world that are influenced
somewhat to greatly, during an ENSO event.
Rainfall data from land and island stations were used to
extend this index back in time and to compare it with the
ENSO sea-surface temperature and atmospheric pressure. The
results showed a strong relationship between the rainfall
patterns and ENSO. "The fact that the rain-change index,
which comes directly from global measurements, tracks the
ENSO indices from the 1950s to the present confirms that El
Nino is the principal driver of global year-to-year rainfall
change," Haddad said.
NASA plans the Global Precipitation Measurement mission
(GPM), a future multi-national multi-satellite mission to
expand the scope of TRMM. GPM will focus on producing three-
dimensional maps of rain around the world every three hours.
TRMM is the first space-based rain gauge that uses microwaves
to see how much precipitation falls from clouds around the
tropics. The TRMM satellite's precipitation radar acts like a
highly sensitive microwave camera. It is capable of probing
clouds to reveal their vertical structure and precipitation
they produce. It has enabled scientists to measure rainfall
over the oceans and landmasses with unprecedented accuracy.
For more information and images about this story on the
Internet, visit:
http://www.nasa.gov/vision/earth/environment/elnino_rainchang
e.html
For information about NASA and other agency programs on the
Web, visit:
http://www.nasa.gov
-end-
--
---------------------------
Jacques :-)
www.spacepatches.info
Headquarters, Washington Nov. 8, 2004
(Phone: 202/358-0836)
Rob Gutro
Goddard Space Flight Center, Greenbelt, Md.
(Phone: 301/286-4044)
RELEASE: 04-369
TRMM SATELLITE PROVES EL NINO HOLDS THE REINS ON GLOBAL RAINS
NASA scientists recently found the El Nino Southern
Oscillation (ENSO) is the main driver of the change in rain
patterns all around the world.
The NASA and Japan Aerospace Exploration Agency (JAXA)
Tropical Rainfall Measuring Mission (TRMM) satellite has
enabled scientists to look around the globe and determine
where the year-to-year changes in rainfall are greatest. The
TRMM is a joint mission between NASA and JAXA designed to
monitor and study tropical rainfall.
Researchers Ziad Haddad and Jonathan Meagher of NASA's Jet
Propulsion Laboratory, Pasadena, Calif., Robert Adler and
Eric Smith of NASA's Goddard Space Flight Center, Greenbelt,
Md., used TRMM data to identify areas where the year-to-year
change in rainfall between 1998 and 2003 was greatest.
By studying the rain patterns in these areas over the past 50
years, with rain gauge data prior to 1998, they established
the main component of this change in global rainfall is
directly correlated with the El Nino Southern Oscillation.
The study appeared in a recent issue of the Journal of
Geophysical Research-Atmospheres.
Haddad and his colleagues compared local changes in worldwide
rainfall. For years, scientists have known El Nino
drastically modifies rainfall patterns in many regions. For
example, Indonesia and the Northeastern Amazon basin
consistently suffer droughts during El Nino and excessive
rains during La Nina. The Southeastern United States and
California are typically wetter than usual during El Nino and
drier than usual during La Nina.
Scientists also have known several regions with abundant rain
are not influenced by the El-Nino/La-Nina changes, including
the Bay of Bengal and the vast expanse of the Western Pacific
Ocean between the Marshall Islands, Micronesia and the
Marianas.
Until the launch of TRMM in 1997, it was impossible to
accurately measure change in tropical rainfall patterns,
because no instruments were available to record global
rainfall. TRMM uses microwave technology to probe through
clouds and estimate how much rainfall they are producing. The
TRMM data are invaluable over areas where there are no rain
gauges, such as the open ocean.
Using TRMM's measurements, the researchers were able to
condense the year-to-year change in rainfall patterns into a
single rain-change index. The index is a color-coded map that
shows areas of rainfall around the world that are influenced
somewhat to greatly, during an ENSO event.
Rainfall data from land and island stations were used to
extend this index back in time and to compare it with the
ENSO sea-surface temperature and atmospheric pressure. The
results showed a strong relationship between the rainfall
patterns and ENSO. "The fact that the rain-change index,
which comes directly from global measurements, tracks the
ENSO indices from the 1950s to the present confirms that El
Nino is the principal driver of global year-to-year rainfall
change," Haddad said.
NASA plans the Global Precipitation Measurement mission
(GPM), a future multi-national multi-satellite mission to
expand the scope of TRMM. GPM will focus on producing three-
dimensional maps of rain around the world every three hours.
TRMM is the first space-based rain gauge that uses microwaves
to see how much precipitation falls from clouds around the
tropics. The TRMM satellite's precipitation radar acts like a
highly sensitive microwave camera. It is capable of probing
clouds to reveal their vertical structure and precipitation
they produce. It has enabled scientists to measure rainfall
over the oceans and landmasses with unprecedented accuracy.
For more information and images about this story on the
Internet, visit:
http://www.nasa.gov/vision/earth/environment/elnino_rainchang
e.html
For information about NASA and other agency programs on the
Web, visit:
http://www.nasa.gov
-end-
--
---------------------------
Jacques :-)
www.spacepatches.info