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Monday, March 7, 2011

February 2011 SST Anomaly Update

I’ve moved to WordPress.  This post can now be found at February 2011 SST Anomaly Update

The map of Global OI.v2 SST anomalies for February 2011 downloaded from the NOMADS website is shown below.

February 2011 SST Anomalies Map (Global SST Anomaly = +0.098 deg C)

Monthly NINO3.4 SST anomalies have risen from their ENSO season low, heralding the start of the end of this La Niña. The Monthly NINO3.4 SST Anomaly is -1.24 deg C.

The SST anomalies in most ocean basins rose this month. This is likely as response to the ebbing of the La Niña. The Arctic, North Atlantic, and East Indian-West Pacific are the exceptions; the SST anomalies there rose. The result was no change in Northern Hemisphere SST anomalies, and an increase in Southern Hemisphere data, for an increase in global SST anomalies (+0.031 deg C). They are presently at +0.098 deg C.
(1) Global
Monthly Change = +0.031 deg C
(2) NINO3.4 SST Anomaly
Monthly Change = +0.349 deg C

As noted in the post Sea Surface Temperature Anomalies – East Pacific Versus The Rest Of The World, I have added these two datasets to the monthly updates. Both datasets have been adjusted for the impacts of volcanic aerosols, and both are smoothed with 13-month running-average filters to reduce the seasonal noise. The global oceans were divided into these two subsets to illustrate two facts. First, the linear trend of the volcano-adjusted East Pacific (90S-90N, 180-80W) SST anomalies since the start of the Reynolds OI.v2 dataset is basically flat, with a linear trend of only 0.08 deg C per Century.
(3) Volcano-Adjusted East Pacific (90S-90N, 180-80W)

And second, the volcano-adjusted SST anomalies for the Rest of the World (90S-90N, 80W-180) rise in very clear steps, in response to the significant 1986/87/88 and 1997/98 El Niño/La Niña events. It also appears as though the SST anomalies of this dataset are making another shift in response to the most recent ENSO event.
(4) Volcano-Adjusted Rest of the World (90S-90N, 80W-180)

The SST anomalies in the East Indian and West Pacific took a major nose dive this month.

I’ve added this dataset in an attempt to draw attention to what appears to be the upward steps in response to significant El Niño events that are followed by La Niña events.
(5) East Indian-West Pacific (60S-65N, 80E-180)
Monthly Change = -0.005 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 animations included in post La Niña Is Not The Opposite Of El Niño – The Videos further help explain the reasons why East Indian and West Pacific SST anomalies can rise in response to both El Niño and La Niña events.

The MONTHLY graphs illustrate raw monthly OI.v2 SST anomaly data from December 1981 to February 2011.

(6) Northern Hemisphere
Monthly Change = 0.000 deg C
(7) Southern Hemisphere
Monthly Change = +0.055 deg C
(8) North Atlantic (0 to 75N, 78W to 10E)
Monthly Change = -0.119 deg C
(9) South Atlantic (0 to 60S, 70W to 20E)
Monthly Change = +0.210 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. It does not appear as though the South Atlantic will return to the level it was at before that surge, and where it had been since the late 1980s. That is, it appears to have made an upward step and continues to rise. Why? Dunno---yet.

(10) North Pacific (0 to 65N, 100 to 270E, where 270E=90W)
Monthly Change = +0.042 Deg C
(11) South Pacific (0 to 60S, 145 to 290E, where 290E=70W)
Monthly Change = +0.014 deg C
(12) Indian Ocean (30N to 60S, 20 to 145E)
Monthly Change = +0.027 deg C
(13) Arctic Ocean (65 to 90N)
Monthly Change = -0.019 deg C
(14) Southern Ocean (60 to 90S)
Monthly Change = +0.003 deg C

The weekly NINO3.4 SST anomaly data portray OI.v2 data centered on Wednesdays. The latest weekly NINO3.4 SST anomalies are -1.26 deg C.
(15) Weekly NINO3.4 (5S-5N, 170W-120W)

The weekly global SST anomalies are at +0.115 deg C.
(16) Weekly Global

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


HR said...

Thanks Bob,

So you're seeing another step up in global SST? I think some AGW-theory critics were expecting (hoping for) a step down to appear by the end of this La Nina given that solar and many of the natural ossilations have changed direction recently. If it's not CO2, have you any ideas what might be making all the steps upward ones?

Bob Tisdale said...

I'm hoping the AMO will start to decline and/or that there will be a Pacific Climate Shift in the opposite direction. That way it could be determined if the recent warming is simply an "alignment" of multidecadal ocean "cycles".

John said...

Hi Bob -

Do we have any solid theories as to what caused the Pacific Climate Shift? Or any reason to think it will shift in the opposite direction (e.g. analysis showing past shifts occurred)?

Trying to remember, but I can't recall anything specific.

Thanks, as always.

Bob Tisdale said...

John: There are as many theories about the cause of the 1976/77 Pacific climate shift as there are papers. Each paper would offer an additional insight. Two that stand out are (1) a shift in sea level pressure in the North Pacific and (2) a pocket of extratropical warm waters from the below the surface of the South Pacific finding its way into the tropics. I haven't found one that is convincing on its own. 1976/77 was also the end of a multiyear La Nina.

I have read a paper (maybe more than one) about shifts occurring in the 1910s and the 1940s as well, but it would take some time for me to find it (them) again.

Robert said...

Hey Bob,
I was wondering how would one compute an AMO index similar to how it was done over Lucia's (by Zeke) from a practical perspective using KNMI. I can make a gridbox for the North Atlantic just fine but how can I get a series for the rest of the world excluding the North Atlantic?

Bob Tisdale said...

Robert: I discussed the same method of calculating the AMO a few weeks before Zeke in this post:

The reason my graph...
...looks different than Zeke's is due to the differences in the SST datasets.

I discussed that with Zeke on Zeke's AMO post at Lucia's.

Bob Tisdale said...

Robert: I forgot to tell you. In the post I linked for you the other day about calculating the AMO as the difference between the North Atlantic and the Rest of the World SST anomalies, I had used 15% as the scaling factor of the North Atlantic. The 15% was 1/2 of the 30% represented by the surface area of the Atlantic (North and South) when compared to the rest of the world WITHOUT the Arctic and Southern Oceans. That is, using the surface areas of the Atlantic, Indian and Pacific Oceans, the Atlantic represents about 30% of the global surface area. Half of that is obviously 15%. This seemed appropriate as a ballpark number since GISS deletes most of the Southern and Arctic Oceans. However, if you include the Southern and Arctic Oceans, the percentage of the North Atlantic would drop to around 12%. If you include only the surface area of the coordinates used in the post, that scaling factor for the North Atlantic would drop to around 11.5%.


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