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TOPEX/El Niño Watch - La Niñ
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PIA01525
Sol (our sun)
Altimeter
| Title |
TOPEX/El Niño Watch - La Niña Weakening, January 17, 1999 |
| Original Caption Released with Image |
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 January 17, 1999, sea surface height is an indicator of the heat content of the ocean. This image shows that the unusual large-scale warming (shown here in red and white) in the northwest Pacific that was first observed by the satellite in November 1998 has increased in size and spread east to the central Pacific and south to the equator. The low sea level or cold pool of water along the equator, commonly referred to as La Niña (shown in purple), has weakened in size and heat content during the last several months. Although weakening, the La Niña pattern continues to exert a strong influence on the worldwide climate system. According to oceanographers, the cold La Niña water acts like a boulder in a stream, steering the planet's prevailing winds and changing the course of storms that are born over the ocean. Equally important to North America's winter weather is the very large area of unusually warm Western Pacific ocean. Although the appearance of this feature is not fully understood or anticipated, it is adding energy to the winter storms coming out of the North Pacific which is fueling the very volatile weather over the continental U.S. In this image, the white areas show 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. The purple areas are 14 to 18 centimeters (6 to 7 inches) below normal and the blue areas are 5 to 13 centimeters (2 to 5 inches) below normal. For more information, please visit the TOPEX/Poseidon project web page at http://topex-www.jpl.nasa.gov |
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TOPEX/El Niño Watch - La Niñ
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PIA01526
Sol (our sun)
Altimeter
| Title |
TOPEX/El Niño Watch - La Niña Hangs On, February 27, 1999 |
| Original Caption Released with Image |
Propulsion Laboratory for NASA's Office of Earth Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA., The cold pool of water in the Pacific known as "La Niña" still persists, although it is slowly weakening, according to scientists studying new data from the U.S.-French TOPEX/Poseidon satellite. A new image, produced using sea-surface height measurements taken by the satellite, is available on the Internet at http://www.jpl.nasa.gov/elnino/. It shows sea-surface height on February 27, 1999 relative to normal ocean conditions, reflecting the heat content of the ocean. The low sea level or cold pool of water along the equator (shown in purple and blue), commonly referred to as La Niña, still dominates the equatorial Pacific Ocean. This La Niña, which first appeared in May through June 1998, still persists, although it is slowly weakening, scientists say. Given its persistence and present strength, the ocean cooling trend is expected to continue to exert a strong influence on global climate systems throughout the spring and into the early summer. This situation is similar to the 1997-1998 El Niño, which extended into early summer 1998. The world's oceans are the great reservoirs of heat that influence global climate because they can cool or heat the atmosphere above. This transfer of heat drives weather patterns across both land and sea. La Niña provides a physical link connecting the large, slow changes in the ocean with predictable changes in day-to-day weather."La Niña shifts the high-altitude weather highway known as the jet stream," said Dr. William Patzert, an oceanographer at NASA's Jet Propulsion Laboratory. "It funnels storm tracks to the Pacific Northwest, which has resulted in heavy rainfall and lots of snow in that region so far, as well as the upper Midwest. Much of the Southwest, by contrast, has been shielded from stormy weather and, as a result, has received significantly less precipitation than normal to date. This year's La Niña was average in its intensity, but at its peak, it was associated with a 15 to 20-centimeter deep trough (6 to 8 inches) in the central tropical Pacific," Patzert said. "The depression was correlated with a 2 to 3-degree Centigrade (about 3.5 to 5.5 degrees Fahrenheit) dip in normal ocean surface temperatures." The image also shows that the very large, unusual area of higher or warmer water (shown here in red and white) in the western Pacific Ocean, from the tropics to the Gulf of Alaska, continues to expand. Although the appearance of this feature is not fully understood, it is recognized as influential to overall weather and climate. The white areas in the image indicate that the sea-surface height is between 14 and 32 centimeters (6 to 13 inches) above normal, in the red areas, sea-surface height is about 10 centimeters (4 inches) above normal. The green areas indicate normal conditions. The purple areas are between 14 to 18 centimeters (6 to 7 inches) below normal, and the blue areas are between 5 to 13 centimeters (2 to 5 inches) below normal. The TOPEX/Poseidon mission is managed by the Jet |
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