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Monday, April 19, 2010

Mid-April 2010 SST Anomaly Update

I’ve moved to WordPress.  This post can now be found at Mid-April 2010 SST Anomaly Update
NOTE: The weekly OI.v2 SST data is available in two periods through the NOAA NOMADS website, from November, 1981 through 1989, and from 1990 to present. I’ve been providing these mid-month updates with graphs that include the full term of the second batch of data. It’s really impossible to tell from those graphs what has transpired over the past few weeks due to the length of the dataset, so I’ve added shorter-term graphs, beginning in 2004, to make the wiggles visible.


NINO3.4 SST anomalies for the week centered on April 14, 2010 show that central equatorial Pacific SST anomalies are continuing to decline. Presently they’re at 0.84 deg C, which is still well into El Nino temperature levels.
NINO3.4 SST Anomalies
NINO3.4 SST Anomalies - Short-Term

Weekly Global SST anomalies are still elevated, near the peak levels for this El Nino. They are not showing any signs, yet, of dropping in response to the decline in central equatorial Pacific temperatures.
Global SST Anomalies
Global SST Anomalies - Short-Term

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


magellan said...

Any guess as to why SST have not yet begun their descent?

Bob Tisdale said...

d: After the 1997/98 El Nino, the Global SST anomalies did not start to decline until September.

A look at a comparison graph of Northern and Southern Hemisphere SST anomalies can help explain why Global SST anomalies appear to linger at the peak SST anomalies. Note the opposing seasonal components of the hemispheric datasets. The Southern Hemisphere anomalies vary much less than the Northern Hemisphere. (The oceans of the Southern Hemisphere cover a larger global surface area than the Northern Hemisphere, so the Southern Hemisphere data contributes more to the global average.) Note also how, during the 1997/98 El Nino, there are two peak Northern Hemisphere SST anomalies. The initial rise and the first peak are combined effects of the El Nino and the Northern Hemisphere seasonal component. The Northern Hemisphere seasonal component then appears to override the El Nino, causing an initial drop. But since the El Nino is still in progress when the 1998 seasonal component starts its rise, there is a secondary spike in the Northern Hemisphere SST anomalies.

The Northern Hemisphere “Secondary El Nino Peak” effect does not appear in the years of the lesser El Nino events, but it does seem to be showing up for the 2009/10 El Nino.

This sounds like a good idea for a post. Thanks.

John said...

Hi Bob -

I think I may have asked this before, but I'm drawing a blank if I really did.

Have you heard anything discussing the hot spot in the South Atlantic?

I've heard the anomalies off the coast of Africa in the North Atlantic may be a combo of Nino and decreased dust storms in Africa, but I've not heard anything discussing the South Atlantic.

Thanks, and apologies if this is a repeat.


Bob Tisdale said...

John: You asked, "Have you heard anything discussing the hot spot in the South Atlantic?"

It's not a repeat. And I assume you're asking about the large area of the South Atlantic between 30S and 10S from coast to coast in this map:

I would think it's also caused by the El Nino. Unfortunately, it doesn't really show up in the Unisys SST animation:

Bob Tisdale said...

John: I took a closer look at the South Atlantic:

You're right. That is odd. I'll try to look into it this week.

Anonymous said...


Some interesting paleo-oscillation papers to be presented here:


Bob Tisdale said...

Anonymous: Thanks for the paleo link.



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