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Monday, December 28, 2009

NINO3.4 SST Anomalies Are Approaching 2 Deg C

I’ve moved to WordPress.  This post can now be found at NINO3.4 SST Anomalies Are Approaching 2 Deg C
While the 2009/10 El Nino is still far from “Super El Nino” strength, NINO3.4 SST anomalies (OI.v2) for the week centered on December 23, 2009 have reached 1.94 deg C.
Weekly NINO3.4 SST Anomalies

The increase is also visible in a .gif animation of the global SST anomalies for the last 4 weeks.
Global SST Anomaly Animation

Referring to the NOAA Equatorial Pacific Temperature Depth Anomaly Animation webpage…
…more warm subsurface water may rise to the surface during this El Nino.
NOAA Equatorial Pacific Cross-Section - Temperature Anomaly Animation

Preliminary monthly NINO3.4 SST anomalies for December 2009 show an increase of 0.14 deg C to 1.81 deg C.
Preliminary December 2009 NINO3.4 SST Anomalies

And the preliminary global SST anomalies for December 2009 are showing an increase of 0.03 deg C to 0.29 deg C.
Preliminary December 2009 Global SST Anomalies

The preliminary monthly SST Anomalies are presented by the NOAA NOMADS webpage, but they will be updated over the next few weeks and will be finalized on January 11, 2010, according to the OI.v2 FAQ webpage:

And for those wondering about the hotspot in the mid-to-high latitudes of central South Pacific, it is an area that is correlated with NINO3.4 SST anomalies. Refer to the following maps of time sequence of temperature anomaly correlations from Trenberth et al (2002) "Evolution of El Nino–Southern Oscillation and global atmospheric surface temperatures":http://www.cgd.ucar.edu/cas/papers/2000JD000298.pdf

Trenberth et al (2002) Figure 8

OI.v2 SST data is available through the NOAA NOMADS webpage:


Anonymous said...

What about the El Niño Modoki index?
It is there any indication of this El Niño turning to a traditional one?

By the way, what is the formula to calculate the El Niño Modoki index?

Bob Tisdale said...

Anonymous 11:35AM: You asked, "What about the El Niño Modoki index? It is there any indication of this El Niño turning to a traditional one?"

It's looking like an El Nino Modoki event.

You asked, "By the way, what is the formula to calculate the El Niño Modoki index?"

Refer to this post:

John said...

Hi Bob -

I was looking at your past Modoki posts and had a question - have any of the prior El Ninos that created step changes been Modoki events? It didn't look like it from the graph I saw in your initial Modoki post (in fact the Modoki index seems strongly negative for some of the step-change events).

Just curious if you think if the Modoki factor plays an influence in the step-change nature of an El-Nino.

Bob Tisdale said...

John: I’ve been calling the 1986/87/88 El Nino a traditional El Nino, but was it really? The 1986 portion of it was an El Nino Modoki:
And in 1987, the El Nino Modoki Index just squeaks into El Nino Modoki territory.

Looks like I’ll have to go back and change the wording regarding the step changes from “significant traditional El Nino events” to “strong El Nino events.”

Will the 2009/10 El Nino also cause a step change? We shall see in a year or two.

Anonymous said...

Just stopped by to assist with your "hit envy." All the best in 2010.

Do you have anything up on why the trade winds slacken at the initiation of El Nino? It seems a rather key process...

Bob Tisdale said...

Anonymous 3:04PM: You asked, "Do you have anything up on why the trade winds slacken at the initiation of El Nino?"

Unfortunately, no. I recall reading a paper a while ago that presented the initiators of a number of El Nino events, but I can't recall its title. I want to say the paper dealt with the models used to predict ENSO events, and since there were a number of initiators, forecasting was problematic.



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