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Monday, November 8, 2010

October 2010 SST Anomaly Update

I’ve moved to WordPress.  This post can now be found at October 2010 SST Anomaly Update
MONTHLY SST ANOMALY MAPThe map of Global OI.v2 SST anomalies for October 2010 downloaded from the NOAA NOMADS website is shown below. The peak of the seasonal elevated SST anomalies in the North Atlantic appears to have passed. They were enhanced this season by the Arctic sea ice melt associated with the last winter’s El Niño and with the 2009/10 upward shift in South Atlantic SST anomalies. The central equatorial Pacific SST anomalies are continuing their decline, and the Pacific is showing a classic La Niña pattern: Eastern tropical Pacific SST anomalies are depressed while the Kuroshio Extension in the northwest Pacific and the South Pacific Convergence Zone east of Australia have elevated SST anomalies.
October 2010 SST Anomalies Map (Global SST Anomaly = +0.19 deg C)


Global SST anomalies, based on the weekly Reynolds OI.v2 data, have made a rebound and taken another drop over the past month. This can be seen in the graph of weekly Global SST anomalies. The present value is about where it was a month ago, 0.095 deg C.
Weekly Global SST Anomalies

The next graph is a comparison of the global SST anomalies for 2010 compared to 1988, 1998, and 2007. Those were other transition years from El Niño to La Niña. In the graph, the data has been shifted so that the first weeks were all zeroed. The current transition is well within the range of past transitions from El Niño to La Niña.
Comparison Of Transitions From El Niño To La Nina

Monthly NINO3.4 SST anomalies are well below the -0.5 deg C threshold of a La Niña. The Monthly NINO3.4 SST Anomaly is -1.59 deg C. Weekly data has rebounded a bit and is now at -1.3 deg C.

Global SST anomalies took a good drop this month, -0.056 deg C. The decline in the Northern Hemisphere (-0.14 deg C) was partly offset by the increase in the Southern Hemisphere (+0.009 deg C).
Monthly Change = -0.056 deg C
NINO3.4 SST Anomaly
Monthly Change = -0.02 deg C

The SST anomalies in the East Indian and West Pacific made a slight rise this month. Will they continue to rise, noticeably, in response to the La Niña as they have in the past?

I’ve added this dataset in an attempt to draw attention to what appears to be the upward step responses. 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 = -0.007 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 November 1981 to October 2010.

Northern Hemisphere
Monthly Change = -0.139 deg C
Southern Hemisphere
Monthly Change = +0.009 deg C
North Atlantic (0 to 75N, 78W to 10E)
Monthly Change = -0.087 deg C
South Atlantic (0 to 60S, 70W to 20E)
Monthly Change = +0.127 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 = -0.172 Deg C
South Pacific (0 to 60S, 145 to 290E, where 290E=70W)
Monthly Change = -0.082 deg C
Indian Ocean (30N to 60S, 20 to 145E)
Monthly Change = +0.019 deg C
Arctic Ocean (65 to 90N)
Monthly Change = -0.075 deg C
Southern Ocean (60 to 90S)
Monthly Change = -0.031 deg C

The weekly NINO3.4 SST anomaly data illustrate OI.v2 data centered on Wednesdays. The latest weekly NINO3.4 SST anomalies are -1.32 deg C. That’s an increase of about 0.5 deg C since the minimum of about a month ago.
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).


Bill Illis said...

Thanks again Bob,

Just something that looks quite off to me with OI.v2

It looks like there is still a significant seasonality value left in the monthly regional SST series.

The global looks okay but the regional/hemisphere anomalies clearly have a significant seasonal signal remaining.

It might just be a visual artifact but if there is seasonality remaining, it really needs to be fixed and all the analysis based on it has to be redone after it is fixed. If so, it is major error.

Bob Tisdale said...

Bill: The NOAA SST climatology...
...leaves a significant seasonal component in the anomalies. I don't believe it was intentional. It's just that the seasonal cycle has changed significantly in the Northern Hemisphere since the 1997/98 El Nino. There's lots more seasonal sea ice melt contributing to the extra swings in the North Atlantic.


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