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Warm water pool is thinning
February 19, 1998
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 Feb. 5, 1998 and sea surface height is an
indicator of the heat content of the ocean. The area and volume
of the El Niño warm water pool that is affecting global weather
patterns remains extremely large, but the pool has thinned along
the equator and near the coast of South America. This 'thinning'
means that the warm water is not as deep as it was a few months
ago. Oceanographers indicate this is a classic pattern, typical
of a mature El Niño condition that they would expect to see
during the ocean's gradual transition back to normal sea level.
In this image, 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
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 satellite imagery, buoy and ship data,
and a forecasting model of the ocean-atmosphere system, the
National Oceanic and Atmospheric Administration, (NOAA), has
continued to issue an advisory indicating the so-called El Niño
weather conditions that have impacted much of the United States
and the world are expected to remain through the spring.
For more information, please visit the TOPEX/Poseidon project
web page at
http://topex-www.jpl.nasa.gov/
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