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Thursday, January 8, 2009

A Precursor of a Strengthening La Nina?

I’ve moved to WordPress.  This post can now be found at A Precursor of a Strengthening La Nina?
In a November 8, 2008 post Average Subsurface Temperature of the Equatorial Pacific, I discussed a dataset available from the CDC. They call the data Equatorial Upper-Ocean Heat Content Anomalies(1979-present). There they further qualify the data as “Equatorial Heat Content (average temperature in the upper 300 meters, deg C)”. I was disappointed at the time that the data hadn’t been updated since May (last data was for April, 2008), but I returned there and discovered an update that includes December 2008.

Figure 1 is a comparative graph of Average Equatorial Pacific Subsurface Temperature Anomaly and NINO3.4 SST Anomaly from January 2001 to December 2008. The longitudes of the subsurface data [180W-100W] don’t align exactly with NINO3.4 [170W-120W], but as illustrated the two datasets track reasonably well, WITH NINO3.4 LAGGING BY A MONTH OR TWO.
Figure 1

What caught my eye was the December 2008 Equatorial Pacific Subsurface Temperature Anomaly value. It’s presently at -1.44 deg C. If the NINO3.4 SST anomaly follows it, as it tends to do, then the La Nina would strengthen significantly. Unfortunately, tendencies help predictions, but they aren’t always true to form. NINO3.4 SST anomalies don’t always follow the Equatorial Pacific Subsurface Temperature Anomalies, as shown in Figure 2, which is a longer-term comparison. http://i40.tinypic.com/r09jjc.jpg
Figure 2

It’ll be interesting to see what happens.


The source of the Equatorial Pacific Subsurface Temperature Anomaly data is discussed and linked in the opening paragraph.

The Optimally Interpolated Sea Surface Temperature Data (OISST) are available through the NOAA National Operational Model Archive & Distribution System (NOMADS).


Bill Illis said...

Hi Bob,

Yeah, I noticed this too a few days ago. This is clearly an indicator of Nino trends, better correlation than the SOI.

Looks like the La Nina will continue strenthening. How much lower it goes, this indicator doesn't put a bottom on it yet.

Bob Tisdale said...

Bill: The CPC fixed their subsurface equatorial Pacific animation.

There are pockets with anomalies as low as -6 deg C. If they stay intact and make it to the surface, it'll be interesting to watch how other regions respond. I think I'll do a quick post about it.

Erl said...

If the South American waters show warming and an El Nino fills in from the East would it not be indicated that the warmth is arising due to more sunlight on the ocean between 20-40° latitudes, both hemispheres and up and down the coast of the Americas. Check a SST anomaly map like at http://www.eldersweather.com.au/climimage.jsp?i=sstag and notice the development of warm anomalies at these latitudes. Notice the significant anomaly at 30-40°S 90-120°W longitude (also centered on 35°N 150W)and the influx of warm waters towards the Galapagos Islands from the north and south. Notice the warm anomalies that have rapidly developed west of Africa, Madagascar, off the south west of Western Australia and east of Indonesia.

This points towards diminished cloud/ increased sunlight as the source of energy. I see a rapid transition to El Nino by March.

Bob Tisdale said...

Erl: Current films, papers, subsurface equatorial Pacific temperature anomaly data, etc., illustrate an El Nino evolves from west to east, with the Pacific Warm Pool as the major source of the heat. Also, I read a paper recently (can't find it right now) that believed the PWP was fed through a subsurface current from the Northwest Pacific--the Kuroshio Extension area, I believe.


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