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Monday, November 23, 1998 Published at 13:07 GMT


La Nina 'frozen' in the Pacific

Fighting it out in the Pacific - El Nino and La Nina

By BBC News Online Science Editor Dr David Whitehouse

The latest observations of the Pacific Ocean show that there is a stand-off between last year's El Nino event and this summer's La Nina. It leaves scientists wondering what will happen next in the Pacific.

Data obtained with the Topex-Poseidon satellite that measures the height of the oceans suggests that somehow El Nino and La Nina are coexisting in the Pacific.

[ image: Different colours represent different ocean heights]
Different colours represent different ocean heights
In a La Nina, which is the opposite of El Nino, cold water that normally exists along the coast of South America extends to the central equatorial Pacific. During such an event, the trade winds are stronger than normal.

Like El Nino, La Nina also affects global weather patterns. More winter storms are expected in North America.

"The forecasted intensification of the La Nina at the end of 1998 has yet to live up to its billing," said Dr Bill Patzert of Nasa. "The size and heat content of this cold pool of water has remained remarkably stable for the past five months,"


The image shows the state of the Pacific on 8 November.

In the image, purple represents 14-18 cm (6-7 inches) below normal; red 10cm (4 inches) below normal; white 14-32 cm (6-13 inches) above normal, with green representing average conditions.

Sea surface height is an indicator of the heat content of the ocean. It shows that remnants of the higher sea level, warmer El Nino waters still linger north of the equator.

The more recent La Nina event, remains in the centre of the Pacific.

The coexistence of El Nino and La Nina leads oceanographers to believe that the ocean and climate system has not recovered from the record-breaking warming that has taken place during the past two years.

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