Saturday, November 10, 2012

ENSO Update: El Nino Lurking Beneath The Waters

The ENSO state as of now remains troubled, with a large expanse of warm waters below the surface, but very little amounts of warm water are actually reaching the surface, where it matters.

The image above shows the latest observed underwater temperature anomalies. Above normal temperature waters are shown in yellows and oranges, while cooler waters appear in blues. At about the 100-200 meter zone, there is a big body of above normal water to the east of the 180 longitude line. That puts this warm body of water roughly in the Nino 3.4 - Nino 3 regions, known as the area most used for identifying the ENSO state. While this body of water may look pretty strong, observe the cool body of water just developing between 50-300 meters below the surface to the west of the 180 line. This cooling trend has just started developing, and based on an animation of underwater temperature anomalies, this cooling trend should continue. That would eat away at the warm body of water, especially in the Nino 3.4 region.

There is a second warm body of water between the surface-150 meter mark, which is more compact and appears more likely to move to the surface. However, just as the aforementioned body of water is having trouble, this second above-normal body of water is also struggling. If you see the upper-right corner of the picture, you can see a small pocket of much below-normal temperature anomalies. That is just off the coast of South America on the Equator. This pocket of cold water is also eating away at the warm waters, but I have more confidence that this body of warmth will propagate to the surface rather than sit underwater and be slowly eaten away by the cool waters, like what is happening near the 180 longitude line.

Observed sea surface temperatures as of Halloween show pretty much what I was diagnosing in the underwater section below. We can see a warm body of water on the surface to the west of the 180 longitude line, while there is a general mess of above and below normal anomalies to the east of the 180 longitude line. In other words, the areas to the east of this line are undetermined as far as the ENSO state goes.

I expect a warming trend on the surface, focused between the 140-100 W longitude lines as the warm body of water tries to move towards the surface. Cooling is likely just off the immediate S. American coast on the Equator, as the cold pocket I explained above could very well bump up to the surface.

Seeing as the CPC cancelled their El Nino watch (as was widely expected), and the first days of November bring about an undetermined ENSO state, I expect this unknown state to continue through the month of November, possibly in to December. This possibility for December will ride on what the big body of water I mentioned first does.


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