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Monday, May 10, 2010

April 2010 SST Anomaly Update

I’ve moved to WordPress.  This post can now be found at April 2010 SST Anomaly Update

The map of Global OI.v2 SST anomalies for April 2010 downloaded from the NOMADS website is shown below. The drop in central equatorial Pacific SST anomalies toward ENSO-neutral temperatures is obvious. The response should work its way eastward over the next couple of months.
April 2010 SST Anomalies Map (Global SST Anomaly = +0.32 deg C)


NINO3.4 SST anomalies are dropping but El Niño conditions remained during April in the central tropical Pacific (Monthly NINO3.4 SST Anomaly = +0.68 deg C). Weekly data has fallen into ENSO-neutral ranges (+0.30 deg C). Global SST anomalies increased slightly again during April (0.017 deg C). On a hemispheric basis, the rise was limited basically to the Northern Hemisphere, since the increase in the Southern Hemisphere was negligible (0.002 deg C). And looking at the major ocean basins, the North Pacific, South Atlantic, Indian Ocean, and the East Indian-West Pacific Ocean datasets all show drops this month, but they were not strong enough to outweigh the rises in the North Atlantic and South Pacific.
Monthly Change = +0.017 deg C
NINO3.4 SST Anomaly
Monthly Change = -0.46 deg C


The SST anomalies in the East Indian and West Pacific have ended (temporarily) their lagged rise in response to the El Niño . Will they also rise, noticeably, in response to a La Niña as they have in the past? Will there even be a La Niña following this El Niño? Refer to Typical (Average) El Nino, Traditional El Nino, and El Nino Modoki Events.

I’ve added this dataset in an attempt to draw attention to the upward step response. Using the 1986/87/88 and 1997/98 El Niño events as references, East Indian-West Pacific SST Anomalies peak about 7 to 9 months after the peak of the NINO3.4 SST anomalies, so we shouldn’t expect any visible sign of a step change for almost 18 to 24 months. We’ll just have to watch and see.
East Indian-West Pacific (60S-65N, 80E-180)
Monthly Change = -0.114 deg C

Further information on the upward “step changes” that result from strong El Niño events, refer to my posts from a year ago Can El Niño Events Explain All of the Global Warming Since 1976? – Part 1 and Can El Niño Events Explain All of the Global Warming Since 1976? – Part 2

And for the discussions of the processes that cause the rise, refer to More Detail On The Multiyear Aftereffects Of ENSO - Part 2 – La Niña Events Recharge The Heat Released By El Niño Events AND...During Major Traditional ENSO Events, Warm Water Is Redistributed Via Ocean Currents -AND- More Detail On The Multiyear Aftereffects Of ENSO - Part 3 – East Indian & West Pacific Oceans Can Warm In Response To Both El Niño & La Niña Events


The MONTHLY graphs illustrate raw monthly OI.v2 SST anomaly data from November 1981 to April 2009.

Northern Hemisphere
Monthly Change = +0.036 deg C
Southern Hemisphere
Monthly Change = +0.002 deg C
North Atlantic (0 to 75N, 78W to 10E)
Monthly Change = +0.156 deg C
South Atlantic (0 to 60S, 70W to 20E)
Monthly Change = -0.037 deg C

Note: I discussed the upward shift in the South Atlantic SST anomalies in the post The 2009/10 Warming Of The South Atlantic.

North Pacific (0 to 65N, 100 to 270E, where 270E=90W)
Monthly Change = -0.083 Deg C
South Pacific (0 to 60S, 145 to 290E, where 290E=70W)
Monthly Change = +0.105 deg C
Indian Ocean (30N to 60S, 20 to 145E)
Monthly Change = -0.072 deg C
Arctic Ocean (65 to 90N)
Monthly Change = +0.024 deg C
Southern Ocean (60 to 90S)
Monthly Change = -0.109 deg C


The weekly NINO3.4 SST anomaly data illustrate OI.v2 data centered on Wednesdays. The latest weekly NINO3.4 SST anomalies are +0.30 deg C. They’re working their way down. How low will they go?
Weekly NINO3.4 (5S-5N, 170W-120W)


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


Andrew said...

Bob, I have a question about the ENSO step change effects you've identified. How long after an El Nino event would the increases in temperature take to dissipate? I find it hard to believe that temperatures would be permanently elevated. Also, what, if anything, could cause a step decrease?

Bob Tisdale said...

Andrew, you asked, "How long after an El Nino event would the increases in temperature take to dissipate?"

On the order of 7 to 8 years for the 1997/98 El Nino, because the shifts are caused by numerous interdependent processes that also take place during the 1998/99/00/01 La Nina, and because subsequent El Nino events, the lesser El Nino Modoki, prolong it. I'm working on a video that will help explain, above and beyond what I've written in the posts so far.

HR said...

Thanks Bob for putting the hard work in on this. Hopefully you're getting some of that Big Oil money, you deserve it ;)

I've got a question about the Arctic Ocean data. Is this ice free areas? Does the area change as the ice retreats? Apart from the recent large spikes there doesn't seem to be much of a trend going on there. Is this because the ice, when it's around, keep the temperatures fairly steady?



Bob Tisdale said...

Pete: You asked, “I've got a question about the Arctic Ocean data. Is this ice free areas?”


You asked, “Does the area change as the ice retreats?”

Yes. A good post to see this is one I did about that spike in 2007. See:

You asked, “Apart from the recent large spikes there doesn't seem to be much of a trend going on there. Is this because the ice, when it's around, keep the temperatures fairly steady?”

The trend since 1981 in the Arctic is slightly higher than the Global trend, and the biggest contributor to that trend is the area North of the North Atlantic, and of course, the North Atlantic has the AMO. Over the long term, the Arctic trend is less than the global trend:

It’s tough to say what’s going on with anomalies in areas with ice melt. In 2007, areas of the Arctic Ocean were exposed that hadn’t been ice free for a while. How then does NOAA calculate an anomaly? NOAA established a climatology that gives temperatures for the ice for each month. If the ice doesn’t melt, the anomaly is zero. When it does melt, then it’s compared to what NOAA thinks the temperature should be. Is the climatology right? Dunno, but it’s a logical way to treat anomalies there.

Volker Doormann said...

Hi Bob,

is it possible to download data files for all the graphs?



Bob Tisdale said...

Volker: All of the data used in the graphs are available through the links at the end of all of my posts. For the monthly updates they are the NOAA NOMADS website here:

or here:



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