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TOPEX/Poseidon image shows El Niño is still strong
September 25, 1997
This image of the Pacific Ocean was produced using sea
surface height measurements taken by the U.S./French
TOPEX/Poseidon satellite. The image shows sea surface height
relative to normal ocean conditions on September 20, 1997 and
provides more convincing information that the weather-disrupting
phenomenon known as El Niño is back and getting stronger. The
white and red areas indicate unusual patterns of heat storage; in
the white areas, the sea surface is between 14 and 32 centimeters
( 6 to 13 inches) above normal; in the red areas, it's about 10
centimeters (4 inches) above normal. The surface area covered by
the warm water mass is about one and one-half times the size of
the continental United States. The added amount of oceanic warm
water near the Americas, with a temperature between 21-30 degrees
Celsius (70-85 degrees Fahrenheit), is about 30 times the volume
of water in all the U.S. Great Lakes combined. The green areas
indicate normal conditions, while purple (the western Pacific)
means at least 18 centimeters (7 inches) below normal sea level.
The El Niño phenomenon is thought to be triggered when the steady
westward blowing trade winds weaken and even reverse direction.
This change in the winds allows a large mass of warm water (the
red and white area) that is normally located near Australia to
move eastward along the equator until it reaches the coast of
South America. The displacement of so much warm water affects
evaporation, where rain clouds form and, consequently, alters the
typical atmospheric jet stream patterns around the world. Using
these global data, limited regional measurements from buoys and
ships, and a forecasting model of the ocean-atmosphere system,
the National Centers for Environmental Prediction (NCEP) of the
National Oceanic and Atmospheric Administration, (NOAA), has
issued an advisory indicating the presence of the early
indications of El Niño conditions.
For more information, please visit the TOPEX/Poseidon project
web page at
http://topex-www.jpl.nasa.gov/
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