Will La Niņa wane as El Niņo lingers?

September 28, 1998
Webposted at 1:45 PM EDT

By Environmental News Network staff

The tropical Pacific Ocean continues to exhibit the complicated characteristics of both a lingering El Niņo, and a possibly waning La Niņa.

(ENN) -- El Niņo continues to linger in the Pacific Ocean and appears to be locked in a battle with a waning La Niņa, according to scientists studying new measurements of sea surface height made by the TOPEX/Poseidon satellite.

The image shows that the rapid cooling that had occurred in the central tropical Pacific has slowed and the area of low sea level, or cold water that is sometimes referred to as La Niņa, has slightly decreased in size and strength since August.

Scientists are still uncertain whether or not this cold pool will evolve into a long-lasting La Niņa situation.

The Sept. 12 image shows sea-surface height 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 Niņo, and a possibly waning La Niņa situation. The coexistence of these two contrasting conditions indicates that the ocean and the climate system remain in transition.

The patterns are expected to remain in the climate system for many months and will continue to influence weather conditions around the world in the coming fall and winter.

A La Niņa is essentially the opposite of an El Niņo condition, but during a La Niņa 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 Niņo, a La Niņa 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.

During a La Niņa, weaker wintertime jet streams are expected to prevail over the central and eastern Pacific. Enhanced monsoons are expected over Southeast Asia, South and Central America and Africa.

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