El Nino and La Nina at a standoff

Warmer El Nino waters still linger to the north of the equator while the area of low sea level, or cold water that is sometimes referred to as La Nina, remains in the center of the Pacific

October 27, 1998
Web posted at: 5:20 PM EDT

By Environmental News Network staff

(ENN) -- El Nino and La Nina are battling for dominance in the tropical Pacific Ocean leaving scientists uncertain as to whether the ocean is headed toward a long-term La Nina situation.

The news comes from analysis of the latest image of sea surface height from the TOPEX/Poseidon satellite which has provided the background for El Nino and La Nina forecasts over the past year.

The new image shows that sea level across the tropical Pacific has essentially maintained the same pattern since mid-June. Remnants of the high sea level, warmer El Nino waters still linger to the north of the equator while the area of low sea level, or cold water that is sometimes referred to as La Nina, remains in the center of the Pacific.

The image shows sea-surface height on Oct. 12, relative to normal ocean conditions. Sea surface height is an indicator of the heat content of the ocean; the pool of cold water in the Pacific is detected by the satellite as a region of lower than normal sea level.

The tropical Pacific Ocean continues to exhibit the complicated characteristics of both a lingering El Nino and a possibly waning La Nina situation. The coexistence of these two contrasting conditions indicates that the ocean and the climate system remain in transition.

These strong patterns have remained in the climate system for many months and will continue to influence weather conditions around the world this fall and winter.

A La Nina is essentially the opposite of an El Nino condition. During a La Nina the trade winds are stronger than normal and the cold water that normally exists along the coast of South America extends to the central equatorial Pacific. Like El Nino, a La Nina situation also changes global weather patterns and is associated with less moisture in the air resulting in less rain along the west coasts of North and South America.

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