The Relationship Between ENSO And Global Surface Temperature Is Not Linear

I’ve moved to WordPress.  This post can now be found at The Relationship Between ENSO And Global Surface Temperature Is Not Linear

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INTRODUCTION

The first part of this post is a rehashing of points made in earlier posts here and at WattsUpWithThat, including “Multiple Wrongs Don’t Make A Right, Especially When It Comes To Determining The Impacts Of ENSO”, and “Regression Analyses Do Not Capture The Multiyear Aftereffects Of Significant El Nino Events.” I will keep repeating the message with each new paper that attempts to perpetuate the misconceptions, or misunderstandings, or misinterpretations of ENSO until the message gets through.

The point introduced in this post: The message has landed in at least one paper, but more on that in the Closing.

Expect to find a repeat of this message as soon as the Journal of Climate publishes the 2009 Thompson et al paper “Identifying signatures of natural climate variability in time series of global-mean surface temperature: Methodology and Insights.” It also fails to account for the long-term cumulative effects of ENSO on Global Surface Temperature.

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Lean and Rind in their 2009 paper “How Will Earth’s Surface Temperature Change in Future Decades?” make a common error. Link to Lean and Rind (2009):
http://pubs.giss.nasa.gov/docs/2009/2009_Lean_Rind.pdf

And there are many other papers that err in the same way. These include:

Foster et al (In Press) “Comment on ‘Influence of the Southern Oscillation on tropospheric temperature’” JOURNAL OF GEOPHYSICAL RESEARCH, VOL. ???, XXXX, DOI:10.1029/
Link:
http://www.cgd.ucar.edu/cas/Trenberth/trenberth.papers/Foster_et%20alJGR09_formatted.pdf

Lean and Rind (2008) “How Natural and Anthropogenic Influences Alter Global and Regional Surface Temperatures: 1889 to 2006” [GEOPHYSICAL RESEARCH LETTERS, VOL. 35, L18701, doi:10.1029/2008GL034864, 2008].
Link:
http://pubs.giss.nasa.gov/docs/2008/2008_Lean_Rind.pdf

Santer, B.D., Wigley, T.M.L., Doutriaux, C., Boyle, J.S., Hansen, J.E., Jones, P.D., Meehl, G.A., Roeckner, E., Sengupta, S., and Taylor K.E. (2001), “Accounting for the effects of volcanoes and ENSO in comparisons of modeled and observed temperature trends,” J. Geophys. Res., 106, 28033–28059.
Link:
http://pubs.giss.nasa.gov/docs/2001/2001_Santer_etal.pdf

Thompson, D. W. J., J. J. Kennedy, J. M. Wallace, and P. D. Jones (2008), “A large discontinuity in the mid-twentieth century in observed global-mean surface temperature,” Nature, 453, 646–650, doi:10.1038/nature06982.
Link:
http://www.nature.com/nature/journal/v453/n7195/abs/nature06982.html

Trenberth, K.E., J.M.Caron, D.P.Stepaniak, and S.Worley, (2002), “Evolution of El Nino-Southern Oscillation and global atmospheric surface temperatures,” J. Geophys. Res., 107 (D8), 4065, doi:10.1029/2000JD000298
Link:
http://www.cgd.ucar.edu/cas/papers/2000JD000298.pdf

Wigley, T. M. L. (2000), “ENSO, volcanoes, and record-breaking temperatures,” Geophysical Res. Lett., 27, 4101–4104.ENSO, volcanoes and record‐breaking temperatures
Link:
http://www.agu.org/pubs/crossref/2000/2000GL012159.shtml

All of these papers assume that the relationship between ENSO and Global Surface Temperature is linear. Lean and Rind (2009) present this assumption in their Figure 1, which is Figure 1 of this post.




http://i32.tinypic.com/35kjsoy.png
Figure 1

Note how the ENSO signal in Cell B of Figure 1 is fundamentally a scaled-down version of the Multivariate ENSO Index or MEI. Lean and Rind note the use of the MEI, “The multivariate ENSO index, E, is a weighted average of the main ENSO features contained in sea-level pressure, surface wind, surface sea and air temperature, and cloudiness [Wolter and Timlin, 1988].” The other papers noted above use others ENSO indices such as Southern Oscillation Index data, NINO3.4 or NINO3 SST anomalies, or Cold Tongue Index SST anomalies as their ENSO reference, and they all make the same erroneous assumption.

The assumption made is that the relationship between ENSO and Global Surface Temperature is linear. It is not. There are residual effects of significant El Nino events, like those in 1986/87/88 and 1997/98. These residual effects create upward step changes in Global Surface Temperatures, Figure 2, that are seen as divergences between the ENSO signal and Global Surface Temperatures. These divergences are mistaken for the impacts of Anthropogenic influences.


http://i29.tinypic.com/25gv2j5.png
Figure 2

As noted in Figure 2, these step changes are easily seen in two datasets. The first is the SST anomalies of the Eastern Indian and Western Pacific Oceans, Figure 3.
http://i31.tinypic.com/24l5rlw.png
Figure 3

The area represented by the East Indian and West Pacific Ocean SST anomalies (the black curve in Figure 3) is shown in Figure 4. The coordinates are 60S to 65N, 80E to 180. It occupies a significant portion of the world oceans, in the range of 25 to 30% of global sea surface from 60S to 65N.
http://i39.tinypic.com/5n55as.jpg
Figure 4

Refer to the following posts for further information:
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

The second dataset these step changes in response to the 1986/87/88 and the 1997/98 El Nino events can be seen in are the TLT anomalies of the Mid-to-High latitudes of the Northern Hemisphere, Figure 5. The 1986/87/88 and 1997/98 El Nino events are highlighted in the Hovmoller.
http://i31.tinypic.com/71r08x.jpg
Figure 5

Refer to my post:
“RSS MSU TLT Time-Latitude Plots...Show Climate Responses That Cannot Be Easily Illustrated With Time-Series Graphs Alone”.

CLOSING

The myths of Anthropogenic Global Warming are maintained by the continued misrepresentation of the impacts of ENSO on Global Surface Temperatures. But as noted in the Introduction, at least one paper, Stockwell and Cox (Submitted) “Comment on ‘Influence of the Southern Oscillation on tropospheric temperature’ by J. D. McLean, C. R. de Freitas, and R. M. Carter”, has proposed an alternate explanation.

Link to abstract:
http://arxiv.org/abs/0908.1828

Stockwell and Cox write in the abstract, “We demonstrate an alternative correlation between the El Nino Southern Oscillation (ENSO) and global temperature variation to that shown by McLean et al. [2009]. We show 50% of the variation in RATPAC-A tropospheric temperature (and 54% of Had-CRUT3) is explained by a novel cumulative Southern Oscillation Index (cSOI) term in a simple linear regression. We review evidence from physical and statistical research in support of the hypothesis that accumulation of the effects of ENSO can produce natural multi-decadal warming trends. Although it is not possible to reliably determine the relative contribution of anthropogenic forcing and SOI accumulation from multiple regression models due to collinearity, these analyses suggest that an accumulation ratio cSOI/SOI of 4:8 +/- 1:5% and up to 9 +/- 2% is sufficient for ENSO to play a large part in the global mean temperature trend since 1960.”

In time, maybe (maybe not), the true nature of ENSO will be accounted for by climate scientists in their analyses and GCMs. Until that time, I will continue to repeat what I’ve documented in numerous ways. The relationship between ENSO and global surface temperature is not linear.

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H/T to David Whitehouse who noted in his post Forecasting the Earth’s Temperature that Lean and Rind (2009) had been published.

August 2009 SST Anomaly Update

I’ve moved to WordPress.  This post can now be found at August 2009 SST Anomaly Update

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MONTHLY SST ANOMALY MAP

The map of Global OI.v2 SST anomalies for August 2009 downloaded from the NOMADS website is shown below.
http://i32.tinypic.com/2rcbdx2.png
August 2009 SST Anomalies Map (Global SST Anomaly = +0.28 deg C)

MONTHLY OVERVIEW

Global SST anomalies rose 0.004 deg C between July and August. In other words, for all intents and purposes, they remained unchanged. The equatorial Pacific continues to show weak El Nino conditions (Monthly NINO3.4 SST Anomaly = +0.81 deg C and Weekly NINO3.4 SST Anomaly = +0.89 deg C). Monthly NINO3.4 SST anomalies dropped a small amount (-0.05 deg C) in August, while the weekly data shows NINO3.4 SST anomalies have been modulating slightly for the past few weeks.
http://i31.tinypic.com/2wbui5v.png
Global
Monthly Change = +0.004 deg C
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http://i25.tinypic.com/5mc0wk.png
NINO3.4 SST Anomaly
Monthly Change = -0.052 deg C

NOTE ABOUT THE DATA

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

MONTHLY INDIVIDUAL OCEAN AND HEMISPHERIC SST UPDATES
http://i30.tinypic.com/24gom83.png
Northern Hemisphere
Monthly Change = +0.019 deg C
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http://i26.tinypic.com/22drgp.png
Southern Hemisphere
Monthly Change = -0.008 deg C
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http://i26.tinypic.com/2e64is9.png
North Atlantic (0 to 75N, 78W to 10E)
Monthly Change = -0.047 deg C
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http://i30.tinypic.com/2ir42lf.png
South Atlantic (0 to 60S, 70W to 20E)
Monthly Change = -0.132 deg C
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http://i30.tinypic.com/2iawwt3.png
North Pacific (0 to 65N, 100 to 270E, where 270E=90W)
Monthly Change = -0.019 Deg C
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http://i25.tinypic.com/4kgryr.png
South Pacific (0 to 60S, 145 to 290E, where 290E=70W)
Monthly Change = +0.027 deg C
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http://i26.tinypic.com/fm51e0.png
Indian Ocean (30N to 60S, 20 to 145E)
Monthly Change = +0.034 deg C
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http://i31.tinypic.com/24cf8yg.png
Arctic Ocean (65 to 90N)
Monthly Change = +0.379 deg C
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http://i32.tinypic.com/2vjxtp1.png
Southern Ocean (60 to 90S)
Monthly Change = +0.047 deg C

WEEKLY NINO3.4 SST ANOMALIES

The weekly NINO3.4 SST anomaly data illustrate OI.v2 data centered on Wednesdays. The latest weekly NINO3.4 SST anomalies are +0.895 deg C.
http://i27.tinypic.com/5ujod3.png
Weekly NINO3.4 (5S-5N, 170W-120W)

SOURCE

The Optimally Interpolated Sea Surface Temperature Data (OISST) are available through the NOAA National Operational Model Archive & Distribution System (NOMADS).
http://nomad3.ncep.noaa.gov/cgi-bin/pdisp_sst.sh?lite

ENSO Dominates NODC Ocean Heat Content (0-700 Meters) Data

I’ve moved to WordPress.  This post can now be found at ENSO Dominates NODC Ocean Heat Content (0-700 Meters) Data

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UPDATE October 19, 2009

On October 15, 2009, the NODC corrected errors in the Ocean Heat Content data for the period of April through June 2009. This post has been updated with that corrected data.

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The Royal Netherlands Meteorological Institute (KNMI) recently added the National Oceanographic Data Center (NODC) Ocean Heat Content (OHC) dataset to their Climate Explorer website, allowing users to download data based on user-defined global coordinates.
http://climexp.knmi.nl/selectfield_obs.cgi?someone@somewhere

This OHC dataset was presented in the Levitus et al (2009) paper “Global ocean heat content(1955-2008) in light of recent instrumentation problems” [GEOPHYSICAL RESEARCH LETTERS, VOL. 36, L07608, doi:10.1029/2008GL037155, 2009]ftp://ftp.nodc.noaa.gov/pub/data.nodc/woa/PUBLICATIONS/grlheat08.pdf

There are differences in the presentation of the data. The NODC illustrates their OHC data for the 0 to 700 meter layer in 10^22 Joules, but KNMI presents the data on an area-averaged basis, in units of Gigajoules (10^9 Joules) per square meter. The data is the same; the units in which the data is presented are different. Also, the NODC provides the data on a quarterly basis; that is, the data is grouped in three-month averages. KNMI presents the NODC OHC data on a monthly basis by listing the quarterly data for each of the three months. This is why the OHC data appears to be squared off in the graphs of monthly raw data. This can be seen in Figure 1.

http://i34.tinypic.com/1zgx284.png
Figure 1

Figure 1 is a comparison graph of the Global OHC anomaly data (NODC), scaled NINO3.4 SST Anomalies (HADISST), and scaled Sato Index (GISS) data. This is the same format used in the graphs of the subsets illustrated in this post. The NINO3.4 SST anomalies are used to illustrate the timing of the El Nino-Southern Oscillation (ENSO) events. The Sato Index of Mean Optical Thickness at 500nm are provided to illustrate the timing of explosive volcanic eruptions. I’ve also smoothed the data for each OHC anomaly subset with a 13-month running-average filter, Figure 2.
http://i36.tinypic.com/es58ux.png
Figure 2

NOTE: All OHC anomaly data presented are for the 0-700 meter layer.

TROPICS

The Tropical Pacific OHC anomaly data is illustrated in Figure 3. A number of things to note: The tropical Pacific OHC anomalies fall during El Nino events, but then recharge during the La Nina. For the most part, when the El Nino events occur at the same time as volcanic eruptions, the recharge does not return the OHC anomalies to the value they were at before the El Nino, but if the El Nino occurs without the influence of a volcanic eruption, the La Nina recharges the Tropical Pacific OHC anomalies to the pre-El Nino level. And it does it quickly. Note also how the 1972/73 El Nino event causes an upward step in the OHC anomalies of the Tropical Pacific. The OHC anomalies then decrease gradually, being influenced by the eruptions of El Chichon in 1982 and Mount Pinatubo in 1991, until they rise suddenly in 1995. In an earlier post, I illustrated how a shift in Tropical Pacific Total Cloud Amount may have caused the 1995 rise in Tropical Pacific OHC, providing fuel for the 1997/98 El Nino. Refer to my post Did A Decrease In Total Cloud Amount Fuel The 1997/98 El Nino?
http://i36.tinypic.com/eqwdvl.png
Figure 3

However, the Tropical Indian Ocean OHC anomaly data reveals a sudden decline in 1995. Did a shift of warm water and/or cloud cover from the Tropical Indian Ocean to the Tropical Pacific also fuel the 1997/98 El Nino? I’ll investigate this in a future post. Note how the Tropical Indian Ocean OHC anomalies correlate with NINO3.4 SST anomalies over a large portion of the term of the data, but after 1995, the amplitude of the variations changes drastically.
http://i35.tinypic.com/2pphbf4.png
Figure 4

In Figure 5, I’ve combined the OHC anomaly data for the Tropical Indian and Pacific Oceans. The OHC anomaly data for this subset follows the base of the NINO3.4 SST anomalies remarkably well. The OHC anomalies of the Tropical Indian and Pacific Oceans follow the rise in NINO3.4 SST anomalies after the 1972/73 and 1997/98 El Nino events. In other words, like the Tropical Pacific, there also appears to be a 25-year decay after the upward step from the 1972/73 El Nino (also influenced by the 1982 and 1991 volcanic eruptions), until the 1997/98 El Nino causes another upward step.
http://i38.tinypic.com/25hdezk.png
Figure 5

The step changes in the Tropical Atlantic OHC anomalies are obvious. The first occurred three years after the peak of 1972/73 El Nino, as the NINO3.4 SST anomalies rose from the secondary minimum of the two-year La Nina event. The same thing occurred with the next significant El Nino that was strong enough to generate a La Nina that lasted through two ENSO seasons, and that was the 1997/98 El Nino. Note also how the OHC anomalies of the Tropical Atlantic have been dropping quickly since 2005.
http://i38.tinypic.com/2me2vc1.png
Figure 6

MID-TO-HIGH LATITUDES

The North Pacific OHC anomalies are like no other OHC subset. In 1967, there was a sudden drop in the North Pacific OHC anomalies. Twenty plus years later North Pacific OHC anomalies rebounded. I’ll have to investigate this dataset further in a later post, to try to isolate where the majority of that variability takes place.
http://i35.tinypic.com/s3j1h1.png
Figure 7

As illustrated in Figure 8, the South Pacific OHC anomalies show a sharp upward step change following the 1997/98 El Nino. Between 1971 and 1996, the OHC anomalies oscillate at or near 0 GJ/sq meter. The cause of the small rise between the 1960s and 1970 is elusive, but it’s not a significant rise compared to the upward step after the 1997/98 El Nino.
http://i37.tinypic.com/2vhvkwi.png
Figure 8

The South Indian Ocean OHC anomaly data, Figure 9, shows a decrease from 1955 until the late 1960s. Then the 1968/69/70 El Nino caused a minor rise in OHC anomalies. This was followed by a major upward step from the 1972/73 El Nino. OHC anomalies in the South Indian Ocean remained relatively flat until the eruption of Mount Pinatubo, when the OHC anomalies dipped. The upward step change after the 1997/98 El Nino is hard to miss. The decay until 2006 almost returned the South Indian Ocean OHC anomalies to the pre-1997/98 values, but the El Nino of 2006/07 bumped it back up again.
http://i34.tinypic.com/hrwuva.png
Figure 9

The North Atlantic OHC anomaly data, Figure 10, with its gradual climb, is clearly dominated by the Atlantic Multidecadal Oscillation. The impacts of ENSO events are visible, however. I have investigated the North Atlantic OHC data in a follow-up post “North Atlantic Ocean Heat Content (0-700 Meters) Is Governed By Natural Variables”.
http://i35.tinypic.com/10nb42t.png
Figure 10

There is a clear step change in the South Atlantic OHC anomaly data, Figure 11, following the 1972/73 El Nino. In this case, however, the response appears to be lagged an extra couple of years. The response is so long, it appears to result from the lesser El Nino of 1976/77. The South Atlantic OHC anomalies remain relatively flat until they appear to respond to the 1997/98 El Nino with an upward step that starts again many years after the peak of the El Nino. Why so long?
http://i38.tinypic.com/mwbkoj.png
Figure 11

In the original version of this post, I compared the South Atlantic and Tropical Atlantic OHC data in Figure 12 to illustrate the relationship between the two datasets. I found it detracted from the post, so I’ve deleted it.

DELETED
Figure 12

ARCTIC AND SOUTHERN OCEANS
I’ve provided the Arctic and Southern Ocean OHC anomaly data in Figures 13 and 14, without commentary, for those who are interested in seeing what those curves look like.
http://i33.tinypic.com/25zjazp.png
Figure 13

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http://i33.tinypic.com/2rqgity.png
Figure 14

CLOSING
It is clear that significant El Nino events can and do cause upward step changes in Ocean Heat Content. This indicates that ENSO events do more than simply release heat from the tropical Pacific into the atmosphere. Apparently, El Nino events also cause changes in atmospheric circulation in ways that impact Ocean Heat Content. If and when GCMs are able to recreate the variations in atmospheric circulation that cause these changes in Ocean Heat Content, GCMs may have value in predicting future climate variability. At present, they do not.

SOURCES
The NINO3.4 SST anomaly data is based on HADISST data available through the KNMI Climate Explorer:http://climexp.knmi.nl/selectfield_obs.cgi?someone@somewhere

Sato Index data is available through GISS:http://data.giss.nasa.gov/modelforce/strataer/
Specifically:http://data.giss.nasa.gov/modelforce/strataer/tau_line.txt

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UPDATE October 8, 2009:
KNMI corrected a problem in its NODC Ocean Heat Content data on October 1, 2009. The error grew in effect with the distance from the equator. It changed the scale of the variations but did not drastically change the overall shape of the curves. The problem, therefore, had no real impact on this post, which illustrated the timing of ENSO-induced step changes in a number of ocean subsets. But to prevent a disagreement between the data presented in this post and future ones, I have redone the graphs in the following.

In the original version of the post, I had also provided links to graphs of unsmoothed versions of Figures 3 through 14. I have not provided them in this revision.

This post also updates the data through June 2009.

Regards