The most recent image from the TOPEX/Poseidon satellite shows the area of lower sea level or cold water, commonly referred to as La Nina, is weakening along the equator and there is an unusual buildup of warm water in the Western tropical Pacific.
The image shows sea surface height relative to normal ocean conditions on January 17, 1999 and sea surface height is an indicator of the heat content of the ocean.
Although weakening, the La Nina pattern continues to exert a strong influence on the worldwide climate system. According to oceanographers, the cold La Nina 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. This change of direction brings a heavy dose of precipitation to the Pacific Northwest and upper Midwest of the United States. For Southern California, the general pattern should continue to be a classic La Nina dry pattern with occasional winter storms.
"It might be raining this week, but we're having a very dry rainy season in Southern California," said, JPL's Dr. Bill Patzert, a research oceanographer.
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.
The January 17 image is now available online at:
The U.S./French TOPEX/Poseidon mission is managed by NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, CA.
The above story is based on materials provided by NASA/Jet Propulsion Laboratory. Note: Materials may be edited for content and length.
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