>I will be adding two volcano-adjusted SST anomaly subsets to the monthly updates starting with the February 2011 update. They are the East Pacific, which mimics NINO3.4 SST anomalies, and the Rest of the World, which rises in very clear steps during significant ENSO events.
You may want to bookmark the LINKS TO SST ANOMALY UPDATES for future reference.
I’ve written numerous posts about the upward steps in the Sea Surface Temperature (SST) anomalies of the East Indian-West Pacific Oceans (60S-65, 80E-180). Many of them are linked at the end if this post under the heading of “Further Discussions”. In an upcoming post, which is a continuation of my Comments On Tamino’s AMO Post, I’ll also be illustrating and discussing similar upward steps in the Atlantic Multidecadal Oscillation (AMO) data, which are detrended North Atlantic SST data (0-70N, 80W-0). Refer to Figure 1, which is a .gif animation. As illustrated, ENSO- and Volcano-adjusted AMO data rise in steps during the transitions from El Niño to La Niña, but between the upward steps, they mimic the inverted NINO3.4 SST anomalies.
Similar upward steps can also be illustrated if we divide the global oceans into two subsets so that one of them contains both the North Atlantic and the East Indian-West Pacific datasets. The two subsets, Figure 2, are the East Pacific Ocean (90S-90N, 180W-80W) and the Rest Of The World (90S-90N, 80W-180E), the latter of the two containing the North Atlantic and East Indian-West Pacific datasets. As we shall see, the East Pacific SST anomalies mimic the variations of ENSO proxies, with little trend, while the SST anomalies of the Rest of the World rise in very clear steps that coincide with the 1986/87/88 and 1997/98 El Niño events.
ACCOUNTING FOR THE IMPACTS OF VOLCANIC ERUPTIONS
I’ll be removing the linear effects of the two major volcanic eruptions, El Chichon and Mount Pinatubo, from the two SST datasets. To determine the scaling factor for the volcanic aerosol proxy, I used a linear regression software tool (Analyse-it for Excel) with global SST anomalies as the dependent variable and GISS Stratospheric Aerosol Optical Thickness data (ASCII data) as the independent variable. The scaling factor determined was 1.431. This equals a global SST anomaly impact of approximately 0.2 deg C for the 1991 Mount Pinatubo eruption. Refer to Figure 3. I’ll use that scaling factor for the East Pacific and Rest of the World datasets.
As shown in Figure 4, the Volcano-adjusted East Pacific SST anomalies vary in concert with the scaled NINO3.4 SST anomalies. There are periodic divergences, but the variations in the East Pacific SST anomalies mimic the commonly used ENSO proxy.
The linear trend for the East Pacific SST anomalies since November 1981 is basically flat, at only 0.08 deg C per Century. Refer to Figure 5.
This obviously means the rise in the global SST anomalies since the start if this satellite-based SST dataset must occur outside of the East Pacific.
REST OF THE WORLD
Figure 6 compares the SST anomalies and the linear trends of the East Pacific and the Rest Of the World. Since November 1981, the SST anomalies of the Rest of the World (90S-90N, 80W-180) have risen at a rate of approximately 1.01 deg C per Century, while the trend of the East Pacific SST anomalies is only 0.08 deg C per Century.
The East Pacific data used in this post represent approximately 33% of the global ocean surface area. (The percentage is based on the NCEP/DOE Reanalysis-2 “Land Mask” data available through the KNMI Climate Explorer.) So we can place the two datasets in perspective by scaling the East Pacific data by a factor of 0.5. Refer to Figure 7. Notice how flat the Rest of the World SST anomalies are after the 1997/98 upward shift. There are some minor fluctuations, but the Rest of the World SST anomalies are essentially flat until 2009/10. Backing up in time, the same could be said for the period from 1987/88 and 1997/98; the volcano-adjusted Rest of the World data also have not risen over that period.
Adding period-average values to the Rest Of The World SST anomalies, Figure 8, makes the upward steps stand out even more. It will be interesting to see where the “July 2009 to Present” SST anomaly average settles out, if it does before the next significant El Niño drives them higher.
In a recent discussion at another blog (I believe it was a discussion of the adjusted AMO data in Figure 1.), an AGW proponent noted that upward shifts in SST anomalies did not disprove the hypothesis of anthropogenic global warming.
As illustrated in this post, the SST anomalies of the East Pacific Ocean, or approximately 33% of the surface area of the global oceans, have risen very little since 1982. And between upward shifts, the trends of the SST anomalies for the rest of the world (67% of the global ocean surface area) remain flat. What processes could cause anthropogenic global warming to work only during the significant El Niño events of 1986/87/88, 1997/98 and 2009/10?
SST anomaly data is available through the NOAA NOMADS website:
The GISS Global Stratospheric Aerosol Optical Thickness data is available here:
My first detailed posts on the multiyear aftereffects of ENSO events are:
Can El Nino Events Explain All of the Global Warming Since 1976? – Part 1
Can El Nino Events Explain All of the Global Warming Since 1976? – Part 2
Supplement To “Can El Nino Events Explain All Of The Warming Since 1976?”
Supplement 2 To “Can El Nino Events Explain All Of The Warming Since 1976?”
And for those who like visual aids, refer to the two videos included in:
La Niña Is Not The Opposite Of El Niño – The Videos.
The impacts of these El Nino events on the North Atlantic are discussed in:
There Are Also El Nino-Induced Step Changes In The North Atlantic
Atlantic Meridional Overturning Circulation Data
As noted earlier, I’ve also written a rebuttal post to Tamino’s AMO Post. I hope to have a new post on the North Atlantic posted in a few weeks.
The posts related to the effects of ENSO on Ocean Heat Content are here:
ENSO Dominates NODC Ocean Heat Content (0-700 Meters) Data
North Atlantic Ocean Heat Content (0-700 Meters) Is Governed By Natural Variables
More detailed technical discussions can be found here:
More Detail On The Multiyear Aftereffects Of ENSO – Part 1 – El Nino Events Warm The Oceans
More Detail On The Multiyear Aftereffects Of ENSO – Part 2 – La Nina Events Recharge The Heat Released By El Nino Events AND…During Major Traditional ENSO Events, Warm Water Is Redistributed Via Ocean Currents.
More Detail On The Multiyear Aftereffects Of ENSO – Part 3 – East Indian & West Pacific Oceans Can Warm In Response To Both El Nino & La Nina Events