La Nina – The Underappreciated Portion Of ENSO
Guest post by Bob Tisdale
Perform a Google Scholar search for documents including “El Nino” in quotes and there will be more than 200,000 results. On the other hand, “La Nina” will only raise 26,000+. Granted, the formal name of the coupled ocean-atmosphere phenomenon in the tropical Pacific is “El Nino-Southern Oscillation”, but that in quotes only returns 28,000+ results. So it appears that El Nino events do get much more “press” from the scientific community than La Nina events.
Figure 1 is a time-series graph of NINO3.4 SST anomalies from January 1979 to January 2010. El Nino events are a warming of the central and eastern tropical Pacific so they are displayed as a Positive SST anomaly, where La Nina events are a Negative. Visually, is the eye drawn to the upward spikes more than it is to the downward troughs? El Nino events are viewed as being larger in magnitude than La Nina events. NINO3.4 SST anomalies peaked at approximately 2.8 deg C during the Super El Nino events of 1982/83 and 1997/98, while the La Nina events that followed them failed to reach -2 deg C. But the La Nina events of 1988/89 and 2007/08 were stronger than the El Nino events that preceded them. (Refer to the note about base years at the end of this post.)
http://i48.tinypic.com/dpikxz.png
Figure 1
El Nino events release heat from the tropical Pacific, and through ocean currents and changes in atmospheric circulation, they raise surface temperatures outside of the tropical Pacific. These upward spikes in global temperatures, Figure 2, call attention to El Nino events during periods when global temperatures are rising. During La Nina events, the tropical Pacific releases less heat than normal, and global temperatures decline, which doesn’t have the same visual impact.
http://i45.tinypic.com/28wjsdy.png
Figure 2
La Nina events are a vital portion of the El Nino-Southern Oscillation coupled ocean-atmosphere process. La Nina events recharge the heat released from the tropical Pacific during the El Nino. Figure 3 is a graph of Tropical Pacific Ocean Heat Content compared to scaled NINO3.4 SST anomalies. Note that most La Nina events do not fully recharge the heat released by the El Nino events. From 1976 to 1994, tropical Pacific Ocean Heat Content dropped almost continuously, with occasional major dips and rebounds as an El Nino discharged heat and the subsequent La Nina partially recharged it. Then, the 1995/96 La Nina event, one that was not particularly strong, replaced all of the heat that had been released (plus some) over that 18-year stretch.
http://i46.tinypic.com/2vja1z5.png
Figure 3
THE 1995/96 LA NINA PROVIDED THE FUEL FOR THE NEXT EL NINO
During a La Nina event, tropical Pacific trade winds rise above normal levels. The increase in trade winds reduces cloud cover. Reduced cloud cover allows more Downward Shortwave Radiation (visible light) to warm the tropical Pacific. These coupled ocean-atmosphere processes associated with La Nina events were discussed in the post 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”.
As noted above, the 1995/96 La Nina was not a strong event, yet it recharged all of the ocean heat that had been released in almost two decades of El Nino events. In “Genesis and Evolution of the 1997-98 El Niño” [ Science 12 February 1999: Vol. 283. no. 5404, pp. 950 – 954, DOI:10.1126/science.283.5404.950], Michael McPhaden explains, “For at least a year before the onset of the 1997–98 El Niño, there was a buildup of heat content in the western equatorial Pacific due to stronger than normal trade winds associated with a weak La Niña in 1995–96.” Link to Science abstract:
http://www.sciencemag.org/cgi/content/abstract/283/5404/950
Link to NOAA copy of McPhaden (1999):
http://www.pmel.noaa.gov/pubs/outstand/mcph2029/text.shtml
So there was a short-term recharge of tropical Pacific Ocean Heat Content in 1995/96, which is very evident in Figure 3. And this short-term buildup of heat content provided the fuel for the 1997/98 El Nino. Contrary to the beliefs of anthropogenic warming proponents the 1997/98 El Nino was NOT fueled by a long-term accumulation of heat from manmade greenhouse gases.
AND THAT 1997/98 EL NINO WAS CALLED THE EL NINO OF THE CENTURY
The 1997/98 El Nino was strong enough to temporarily raise Global Lower Troposphere Temperature anomalies ~0.7 deg C, as illustrated in Figure 4. Note: The period of 1995 to present was used in the following graphs because there have been no explosive volcanic eruptions since 1995 to add unwanted noise to the data.
http://i47.tinypic.com/21nnu4z.png
Figure 4
And referring to Figure 5, Lower Troposphere Temperature anomalies of the Mid-To-High Latitudes of the Northern Hemisphere rose, but remained at elevated levels that varied well above the value in late 1996. This upward step (and a similar but smaller one caused by the 1986/87/88 El Nino) was discussed in the post “RSS MSU TLT Time-Latitude Plots…Show Climate Responses That Cannot Be Easily Illustrated With Time-Series Graphs Alone”.
http://i48.tinypic.com/33p6nbn.png
Figure 5
Sea Surface Temperature anomalies for the Mid-To-High Latitudes of the Northern Hemisphere also rose and remained at an elevated level. Refer to Figure 6, which compares that dataset to scaled NINO3.4 SST anomalies. The latitudes used for the SST anomalies in this illustration are 20N-65N, which are latitudes that have little impact from polar ice. This upward step in the Sea Surface Temperature anomalies for the Mid-To-High Latitudes of the Northern Hemisphere will be discussed in a future post. I have, however, discussed the impacts of El Nino events on the North Atlantic in the post There Are Also El Nino-Induced Step Changes In The North Atlantic. And the North Atlantic is also impacted by the Atlantic Multidecadal Oscillation, but that appears to have peaked in 2005.
http://i46.tinypic.com/2ylpix3.png
Figure 6
And for those wondering how well the SST and TLT anomalies for the Mid-To-High Latitudes of the Northern Hemisphere correlate, I’ve prepared Figure 7. The SST anomaly data were scaled by a factor of 1.8. There are divergences from year to year, but keep in mind that the coverage areas are very different; the TLT anomalies also include data over continental land masses. One thing is certain; the 1997/98 El Nino caused upward steps in both datasets.
http://i49.tinypic.com/2uo2o8y.png
Figure 7
And there are the impacts of the 1997/98 El Nino on the East Indian and West Pacific Oceans (60S-65N, 80E-180), which I first discussed in a series of posts more than a year ago. The 1997/98 El Nino shifted Sea Surface Temperature anomalies upward in this area of the global oceans, too. Refer to Figure 8. The cause of this was discussed in the posts Can El Nino Events Explain All of the Global Warming Since 1976? – Part 1 and Can El Nino Events Explain All of the Global Warming Since 1976? – Part 2.
http://i48.tinypic.com/2qamu88.png
Figure 8
Basically, the warm water that was built up during the 1995/96 La Nina collected below the surface of an area in the western tropical Pacific known as the Western Pacific Warm Pool (to depths of 300 meters). During the 1997/98 El Nino, the warm water contained in the Western Pacific Warm Pool sloshed east and spread across the surface of the central and eastern tropical Pacific. The warmer-than-normal waters raised Sea Surface Temperatures and changed atmospheric circulation. Then, as the La Nina of 1998/99/00/01 progressed, the trade winds, Pacific Equatorial Currents, and a phenomenon known as a Rossby wave returned the remaining surface and subsurface warm water to the western Pacific. Some of the warm water returned to the Pacific Warm Pool, but a major portion of it remained on the surface and was redistributed by ocean currents to western North and South Pacific, and a portion of the warm water migrated to the Eastern Indian Ocean.
BLAME THE 1995/96 LA NINA FOR THE RECORD TEMPERATURES DURING THE 2000s AND IN 2010
So, if you’re wondering why the present moderate El Nino event of 2009/10 is raising global temperatures to record levels, you have to go back in time. The 1995/96 La Nina provided the build-up of warm waters that was then discharged by the 1997/98 El Nino and redistributed by the 1998/99/00/01 La Nina. The end results were upward steps in SST anomalies and TLT anomalies for major portions of the globe.
One of the methods anthropogenic global warming advocates (scientists and bloggers) use to illustrate the assumed effects of greenhouse gases on global temperatures is to illustrate the divergence between the linear trends of global temperatures and a scaled ENSO index such as NINO3.4 SST anomalies. Refer to Figures 9 and 10. But the upward steps illustrated in Figure 5 and 6 bias global temperature data upwards.
http://i46.tinypic.com/2vsl2mr.png
Figure 9
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http://i50.tinypic.com/2d7j0ux.png
Figure 10
And the biases created by those step changes in the SST and TLT anomalies of the Mid-To-High Latitudes of Northern Hemisphere are responsible for much of the differences between NINO3.4 SST anomalies and global temperature anomalies. We can illustrate this looking at the data for the rest of the world; that is, by comparing the linear trend of NINO3.4 SST anomalies with the linear trends the TLT and SST anomalies for the tropics and the Mid-To-High Latitudes of the Southern Hemisphere. Refer to Figures 11 and 12. As shown, the linear trends of the NINO3.4 SST anomalies are slightly negative, but the linear trends for the SST and TLT anomalies of the tropics and Mid-To-High Latitudes of the Southern Hemisphere are relatively flat–much flatter than the global datasets.
http://i50.tinypic.com/vsn97q.png
Figure 11
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http://i49.tinypic.com/11mcj7p.png
Figure 12
That would mean the ENSO-induced step increases in SST and TLT anomalies of the Mid-To-High Latitudes of the Northern Hemisphere caused the vast majority of the positive linear trends for the global SST and TLT anomaly datasets. See Figures 13 and 14, which show the strengths of the positive trends for those areas of the globe.
http://i47.tinypic.com/i4okg2.png
Figure 13
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http://i50.tinypic.com/35347qh.png
Figure 14
Figures 15 and 16 compare the SST and TLT anomalies for the Mid-To-High Latitudes of the Northern Hemisphere to the Global data and to the SST and TLT anomalies for the Mid-To-High Latitudes of the Southern Hemisphere. It should now be clear that the majority of the rises in Global SST and TLT anomalies since 1995 were caused by the 1997/98 El Nino-induced upward steps in the SST and TLT anomalies for the Mid-To-High Latitudes of the Northern Hemisphere.
http://i50.tinypic.com/33p64k1.png
Figure 15
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http://i47.tinypic.com/1zywv8k.png
Figure 16
In short, the effects of the La Nina- and El Nino-induced step changes in the SST and TLT anomalies of Mid-To-High Latitudes of the Northern Hemisphere are mistaken for, and misrepresented as proof of, anthropogenic global warming.
A BRIEF LOOK AT AN EARLIER LA NINA EVENT
The 1972/73 El Nino was a strong ENSO event. NINO3.4 SST anomalies, referring to Figure 17, peaked above 2 deg C. There were only two El Nino events stronger than the 1972/73 El Nino in the second half of the 20th Century, and they were the two Super El Nino events of 1982/83 and 1997/98.
http://i46.tinypic.com/29krqd2.png
Figure 17
But the 1972/73 El Nino shares another superlative with the 1997/98 El Nino. Both El Nino events were followed by La Nina events that lasted through not one ENSO season, not two ENSO seasons—they lasted through three consecutive ENSO seasons. The La Nina event of 1998/99/00/01 recharged the heat content released by the 1997/98 El Nino and returned the tropical Pacific Ocean Heat Content to the new higher levels established during the 1995/96 La Nina. Refer to Figure 18. The La Nina event of 1973/74/75/76 recharged the heat released from the Tropical Pacific by El Nino events during the decade of the early 1960s to the early 1970s. And it also added to the Tropical Pacific Ocean Heat Content.
http://i46.tinypic.com/2vja1z5.jpg
Figure 18
The Pacific Climate Shift of 1976/77 is a much-studied phenomenon. Trenberth et al (2002) discussed the differences in the evolution of El Nino events before and after the shift, and Trenberth et al (2002) referenced other papers that discussed effects of the Pacific Climate Shift on ENSO. Link to Trenberth et al (2002):
http://www.cgd.ucar.edu/cas/papers/2000JD000298.pdf
El Nino events became stronger after the Pacific Climate Shift. The frequency of El Nino events and El Nino Modoki increased. As noted in an early post, The 1976 Pacific Climate Shift, there were notable shifts in the SST anomalies and linear trends of Pacific Ocean basin subsets.
But I have yet to find a paper that attributes the Pacific Climate Shift of 1976/77 to the La Nina event of 1973/74/75/76 or one that even suggests that the 3-year-long La Nina played a role. Yet through known coupled ocean-atmosphere processes, the 1973/74/75/76 La Nina increased the warm water available for the additional El Nino events after 1976 and for the significant El Nino events of 1982/83 and 1986/87/88.
The explosive volcanic eruption of El Chichon may have counteracted the Super El Nino of 1982/83, but the 1986/87/88 El Nino was strong enough to cause upward shifts in the SST and TLT anomalies of the Mid-To-High Latitudes of the Northern Hemisphere, and the SST anomalies of the East Indian and West Pacific Oceans, similar to the shifts caused by the 1997/98 El Nino illustrated in this post.
A NOTE ABOUT BASE YEARS
Note: The relative strengths of El Nino versus La Nina events discussed early in this post would of course depend on the base years chosen for anomalies. And as illustrated in Figure 17 there is a minor difference depending on whether the base years of 1950 to 1979 or 1979 to 2000 are used. The significance of the difference would depend on how the data is being used. Example: A scaled running total of NINO3.4 SST anomalies will reproduce the basic global temperature anomaly curve as illustrated in Reproducing Global Temperature Anomalies With Natural Forcings if the base years are 1950 to 1979. If the base years of 1979 to 2000 are used, the result will not be similar to the global temperature curve.
http://i47.tinypic.com/2wlrkf4.png
Figure 19
CLOSING COMMENT
The La Nina event of 1973/74/75/76 provided the tropical Pacific Ocean Heat Content necessary for the increase in strength and frequency of El Nino events from 1976 to 1995. The 1995/96 La Nina furnished the Ocean Heat Content that served as fuel for the 1997/98 El Nino. And the 1998/99/00/01 La Nina recharged the tropical Pacific Ocean Heat Content after the 1997/98 El Nino, returning it to the new higher level established by the La Nina of 1995/96.
It would appear that La Nina events do all of the work, while El Nino events get all the glory—and the research.
SOURCE
All data for this post is available through the KNMI Climate Explorer:
http://climexp.knmi.nl/selectfield_obs.cgi?someone@somewhere
Bob,
Thanks for your reply. What you have described doesn’t quite get to my point. However, I may have a better picture of your hypothesis because of your discussing the connection of ENSO to the PDO in another posting on this thread. I had assumed your hypothesis is one of explaining a secular increase in global temperature, but now I realize you may be saying that varying intensity of ENSO leads to the longer cycle we call PDO, and, who knows, the PDO leads to longer cycles and so on ad nauseum. We short-lived humans look at the climatic data and think we are looking at a secular trend, but we are simply looking at a long cycle wrought by ENSO. I can accept this as a reasonable possibility.
Did I paraphrase your thinking correctly?
Not exactly. I wouldn’t use the term “boiler phase”. As a heat engine ENSO has a continuously operating “boiler” in the equatorial western Pacific. The boiler does not operate at a constant heat input rate, however. Variations in cloudiness perhaps, and variations in the inflow of surface wind lead to large swings in heat input. This leads to large swings in heat to run the engine itself, which runs spasmodically. Thus, rejected heat in the temperate and polar regions is also spasmodic, and we observe from this occasional runs upward in global temperature, with a slow decay back toward a baseline of some sort.
As an engine running in some sort of cycle, ENSO has to pass back through the same state variables occasionally. I had interpreted Tisdale’s suggestion of steps upward, as saying, in effect, that the engine was now running so as to pass through states of larger magnitude. If you read my posting above at 15:22:18, you’ll see that I now interpret him as saying there are simply long cycles (PDO) driven by shorter ones (ENSO). There is a way to paraphrase Swift in all this, but I don’t quite see how at present.
Pascvaks (12:53:08) : Thanks for the links. I’ll have to study it.
Kids, repeat after me: It´s the sun, It´s the sun. It´s the sun…
Erl Happ: You asked, “Have you checked the relationships between ENSO 3.4 SST anomalies, tropical Pacific SST anomalies and global tropical SST anomalies? I don’t think ENSO 3.4 anomalies are at all representative of the global tropics.”
Yup:
http://i49.tinypic.com/111utmr.png
Looks to me as though Scaled NINO3.4 SST anomalies and the Tropical SST anomalies for the Globe and Pacific all match up quite well. There’s some divergence after the 1997/98 El Nino, but nothing unexpected.
Stephen Wilde: You wrote in reply to Richard M, “If it be the case that the MWP/LIA/ Modern Warm Period cycle is primarily ocean induced then it is outside Bob’s work and implies a possibility that the PDO phase shift is not merely an ENSO artifact but rather an independent feature modifying ENSO over a time scale upon which the longer term ocean cycling interacts with ENSO events.”
As I continuously remind you, without data to support your claims, they are speculation, nothing more.
You wrote, “Indeed it is plausible that longer term ocean cycles (different in each ocean) averaged out globally first affect the air circulations and then affect the Trade Winds resulting in the ENSO cycle.”
More unfounded speculation, without data to support it.
You wrote, and the part of your comment I strongly object to, “Thus possibly (I’m not sure on this yet) Bob could have the causation reversed.”
If you’re not sure, then you have no basis on which to comment. My writings on the relationship between ENSO and the PDO are based on the findings of Newman et al (2003):
http://www.cdc.noaa.gov/people/gilbert.p.compo/Newmanetal2003.pdf
And on Zhang et al (1997), which was the paper that established the calculation of the PDO, and is the method used by Nate Mantua to this day:
http://www.atmos.washington.edu/~david/zwb1997.pdf
If you’d like references for Pacific basin SST anomaly patterns and how they originate in the tropics, refer to Evans et al (2001):
http://iceman2.umd.edu/www/preprints/pdv.pdf
and to Shakun and Shaman (2009):
http://www.leif.org/EOS/2009GL040313.pdf
Ruhroh: You asked, “Is there a level of model which is more simplistic than ‘zero-th’ order?”
I’m in the process of writing a very detailed, very basic multi-part post on the topics discussed in this one. I don’t know your background or how well versed you are on these discussions, but I’ll let you know it is intended for those new to ENSO, AMO, etc. Even has more basic discussions such as why anomalies are used. I’ve written the first part and have managed to keep it free from acronyms (other than two uses of ENSO). But I want to release all of the posts at once, so it may take me another few months to get through it all.
Impressive post, Bob. It seems to have stimulated a lot of curiosity in this field; perhaps some of us are a bit over-stimulated. That means you’ve done a fine job!
And thanks for the link to Dr. Kessler’s FAQs. Very helpful, particularly this: “We don’t know what initiates El Niño. But we do see that it apparently does not take much to destabilize the strong-trade-wind/large-temperature-contrast non-El Niño state discusse(d) in the section above. This is because of ocean-atmosphere coupling.”
My theory, if anybody is interested, is that upwelling cold water in the Eastern Pacific raises the local ocean viscosity and simultaneously increases the density of the air above. (Ocean density will also increase because of plankton, etc.). Eventually, these factors, working in concert, impede the trade winds just enough to trigger the El Niño portion of the cycle. Once that 1/2 meter hump of water begins to slide east from Indonesia, there’s no stopping it.
Other triggers likely exist, as mentioned in the FAQs:
http://faculty.washington.edu/kessler/occasionally-asked-questions.html#q1
Thank you Bob for your help on all of the questions here. One more from me.
-It appears this Nino is dropping quite fast temperature wise,is this an unusual
drop or just the fact that it peaked quickly?
Neutral by April, I say…
Lights are on here:
lgl (09:46:12) “Another interesting question is why didn’t all the other La-Ninas cause steps in OHC, why only the 75 and 95 Ninas? LOD changed from increasing to decreasing around 73 and 93 so I’ll bet those changes in earth rotation are the real cause of the step ups.”
Bob, the 1973/74/75/76 & 1995/96 events correspond with decadal-timescale peaks in the rate of change of terrestrial angular velocity – i.e. -LOD’ – the red curve here…
http://www.sfu.ca/~plv/-LOD_aa_Pr._r.._LNC_NL3a.png
… and with minima in terrestrial nutation obliquity…
http://www.sfu.ca/~plv/NutationObliquity_.png
… and also with negative surges in terrestrial nutation longitude.
As for the trend in step-changes:
http://www.sfu.ca/~plv/CumuSumGLAAM.png
See also a figure on the page lgl points out:
http://www.crces.org/presentations/dmv_ipwp/images/figure5b.gif
lgl, that figure explains a lot:
http://www.crces.org/presentations/dmv_ipwp/images/figure7.gif
Panels c & d help explain patterns here:
http://www.sfu.ca/~plv/fSAM_fAAO..png
For those interested – details here:
http://www.crces.org/presentations/dmv_ipwp/
See particularly:
http://www.crces.org/presentations/dmv_ipwp/images/figure10.gif
and
http://www.crces.org/presentations/dmv_ipwp/images/figure9.gif
… and compare with the lower panels here:
http://www.sfu.ca/~plv/100204.PNG
–
Tenuc, I think those guys are overlooking confounding – see here:
http://www.sfu.ca/~plv/QBO_fGLAAM_fLOD.png
http://www.sfu.ca/~plv/JN_QBO.png [Note: There’s also QBO phase-coherence with interannual aa index, but it’s intermittent & complex.]
Note the slight phase-contrast-shift in the ’60s when LOD suddenly rose sharply – this shows up as a zero-crossing in this plot:
http://www.sfu.ca/~plv/-LOD_aa_Pr._r.._LNC_NL3a.png
Coupling snapped back together following the climate shift:
http://www.sfu.ca/~plv/fLOD_fGLAAM_PhaseCoherence.PNG
Compare with:
http://www.sfu.ca/~plv/100204.PNG
–
Bob Tisdale (09:51:44) “Since the PDO is an aftereffect of ENSO […] ENSO drives the PDO, not vice versa”
Strongly disagree with this portrayal Bob. Oversimplifying the narrative helps it reach some branches of the masses, but there are some bright folks around here who know that an r^2 of 0.5 is missing half of the picture, including what happens around climate regime shifts (as Ninderthana has explained here in the past).
The easy out is to consider that both PDO & ENSO, which are different-timescale manifestations of related processes, are being bounced around by a 3rd factor.
Thanks for the link to Kessler’s FAQ – the speculative notes on priming & triggering are useful in contemplating why interannual filtering methods based on simple concepts from recurrence methodology (like in Tsonis et al.) helps clarify SOI multivariate-phase-coherence timescale.
–
Re: Joe (11:11:55)
Looks like you might have been reading Barkin.
Stephen Wilde, my impression is that you are underestimating the atmosphere. Consider that all it takes is small decadal pressure changes in the atmosphere (think about what this does to wind) to drive cumulative redistribution. See Sidorenkov & Barkin.
–
Bob Tisdale (16:38:30) ” http://i49.tinypic.com/111utmr.png Looks to me as though Scaled NINO3.4 SST anomalies and the Tropical SST anomalies for the Globe and Pacific all match up quite well.”
The 2004 event stands out as an example of when N3.4 does not tell the right story locally. Were I to give a presentation to knowledgeable local folks, they would immediately note the 2004 discrepancy, so thanks to Erl for reminding us to look at related variables that sometimes tell local stories better.
—
lgl, how can we calculate (or download) the eclipse curve?
http://virakkraft.com/uah-rss-moon.png
http://virakkraft.com/enso-solar-eclipse.png
Bob, at (03:38:52), you wrote During a La Nina event, tropical Pacific trade winds rise above normal levels. The increase in trade winds reduces cloud cover. Reduced cloud cover allows more Downward Shortwave Radiation (visible light) to warm the tropical Pacific.” I should have added “…raising tropical Pacific Ocean Heat Content,” to eliminate the possibility of confusion. Note in the above graph how tropical Pacific OHC rises during the La Nina events of 1995/96 and 1998/99/00/01.
The increase in Trade Wind strength reduces cloud cover and thus warms the tropical Pacific. This helps me to understand at least partly the mechanism going on here. I can imagine a circular flow chart with La Nina at the top and El Nino at the bottom as this event seems to be cyclic with amplitude variation. Does such a flow chart exist ?
Thanks for the good work.
Claiming that La Nina events fuel El Nino events is exaggerating one factor at the expense of another.
During a La Nina the trade winds push warm water across the Pacific and cold water upwells behind it and heat is exchanged with the atmosphere. When that warm water reaches the western Pacific it rises and, in the main, tracks back along the equator in the upper atmosphere and loses its heat to space. In contrast, during an El Nino the trade winds cease and the water warms from the sun. This causes upwelling in the central Pacific – a lot of cloud near the dateline – and in this situation the Hadley Cell circulation distributes it into the mid latitudes and further north if the circumpolar jetstreams will allow it to (i.e. the winds aren’t extending a long way south).
This notion of La Nina fuelling El Nino is limited to a shift in the thermocline, from a La Nina condition of a deep thermocline in the west and shallow in the east (i.e. sloping down as you move east to west), to a relatively flat thermocline under El Nino conditions. The depth of the thermocline in the west is somewhat limited because oceanic warming cannot continue indefinitely. Heat is constantly being exchanged with the atmosphere and that causes an uplift, seen as developing cloud. The warmer the water the greater the uplift.
The period 1945-76 saw very few El Nino events and a progressive increase towards La Nina conditions. That sustain period of La Nina conditions wasn’t reflected in the very next El Nino, which according to Bob should have been huge.
And finally I note that Bob wrote his piece without even one mention to last year’s JGR paper that I wrote with two colleagues and in which we discussed how ENSO activity very largely drives subsequent global temperatures. I’m aware that Bob doesn’t seem to like the SOI calculated according to the Troup system, and I wonder why.
Paul Vaughan (20:51:42) :
I haven’t seen a curve. I made it from a file named 5MCSE-Maps-10.pdf
Think it’s http://eclipse.gsfc.nasa.gov/5MCSE/5MCSE-Maps-10.pdf but can’t get there at the moment.
Paul Vaughan (20:51:42)
“The easy out is to consider that both PDO & ENSO, which are different-timescale manifestations of related processes, are being bounced around by a 3rd factor.”
Quite so.
lgl and Paul,
http://virakkraft.com/enso-solar-eclipse.png
That bump at 1976 is veeeery interesting.
Pascvaks (14:02:10) :The new emerging paradigm is the electric nature of the universe, the plasma universe. In this view our sun relates to earth as an anode to a cathode, and by the “solar wind” (solar currents to earth), proton flares and/or GCR (90% protons), change “winds”(field drived) changing climate, Ninos to Nina (clockwise tradewinds to counterclockwise).
This is, of course, “blasphemous” to the accepted creed, but we should risk excommunion, even malediction from the inquisition friars,if we are to go ahead.
John McLean (23:01:53) : You wrote, “Claiming that La Nina events fuel El Nino events is exaggerating one factor at the expense of another.”
I would have to conclude from your opening sentence that you disagree with my presentation and description of the data in this post, John. The graphs present the data, so I have to conclude you disagree with my description of what the graphs show. And I note a not-too-friendly tone in your comment, so I will maintain it in my reply.
You then went on to provide an incomplete and disjointed description of ENSO, John, lasting for a number of paragraphs. Why incomplete and disjointed? Let’s look at a few sentences in your description.
You wrote, “In contrast, during an El Nino the trade winds cease and the water warms from the sun.”
You weren’t very explicit on where the sun warms the water, John. Is it central or western or eastern tropical Pacific? Nor did you describe how the water warms from the sun. Was there a decrease in cloud cover? If so, where? Cloud cover increases over the central and eastern tropical Pacific during an El Nino, and it decreases over the Pacific Warm Pool. Convection and cloud cover follow the location of the warm water. And the variations in downward shortwave radiation oppose the variations in cloud cover. That is, a decrease in cloud cover yields an increase in downward shortwave radiation. Higher trade winds yield less cloud cover over the central and eastern tropical Pacific, which in turn yields more downward shortwave radiation, which in turn yields warmer water. If you were saying that the central and eastern tropical Pacific SST anomalies warm during an El Nino event because of an increase in downward shortwave radiation, you are wrong, John. Over the central and eastern tropical Pacific, cloud cover increases and downward shortwave radiation decreases during an El Nino.
You wrote next, “This causes upwelling in the central Pacific – a lot of cloud near the dateline – and in this situation the Hadley Cell circulation distributes it into the mid latitudes and further north if the circumpolar jetstreams will allow it to (i.e. the winds aren’t extending a long way south).”
There are so many shifts in the topics being discussed in that sentence, John, it’s hard to keep track of them. That’s my example of the disjointed parts of your ESNO description.
Your use of upwelling is associated with warm water, but upwelling is normally associated with cool waters. And your description of why the water warms in the central equatorial Pacific is lacking. The trade winds cause a temperature gradient across the tropical Pacific, with the water in the west warmer than it is in the east. The trade winds also “pile” the warm water in the west so that it is higher in elevation in the west than it is in the east. When the trade winds relax, they no longer hold the warmer water that’s higher in elevation in the west and gravity causes it to slosh east. This raises the temperature of the central and eastern tropical Pacific as the warmer water travels to the east. Your description also fails to include the all-important Kelvin wave(s), but that part’s nitpicky.
I’ve written so many posts about the processes that take place during ENSO events it’s hard to pick a few. I believe if you were to read about ENSO-induced changes warm water volume…
http://bobtisdale.blogspot.com/2008/11/equatorial-pacific-warm-water-volume.html
…and if you were to read about ENSO-induced changes in the Pacific Equatorial Currents and the Pacific Equatorial Countercurrent…
http://bobtisdale.blogspot.com/2009/02/equatorial-currents-before-during-and.html
…and if you were to read about the variations in subsurface equatorial Pacific temperatures…
http://bobtisdale.blogspot.com/2009/02/cross-sectional-views-of-three.html
And:
http://bobtisdale.blogspot.com/2009/02/cross-sectional-views-of-three_28.html
…and if you were to read about ENSO-induced changes in tropical Pacific sea level anomalies…
http://bobtisdale.blogspot.com/2009/12/animations-of-aviso-tropical-pacific.html
(The above posts are descriptions of the linked animations, but I’m sure you could acquire data if you liked and study it.)
…and if you were to study ENSO-induced changes in Downward Shortwave Radiation presented in Pavlakis et al (2008) “ENSO Surface Shortwave Radiation Forcing over the Tropical Pacific” (2008)…
http://www.atmos-chem-phys-discuss.net/8/6697/2008/acpd-8-6697-2008-print.pdf
…and if you were to study Trenberth et al (2002) “Evolution of El Nino–Southern Oscillation and global atmospheric surface temperatures”…
http://www.cgd.ucar.edu/cas/papers/2000JD000298.pdf
…and if you were to read my series of posts on the multiyear aftereffects of ENSO events…
http://bobtisdale.blogspot.com/2009/11/more-detail-on-multiyear-aftereffects.html
AND (with your attention on this one):
http://bobtisdale.blogspot.com/2009/11/more-detail-on-multiyear-aftereffects_26.html
AND:
http://bobtisdale.blogspot.com/2009/12/more-detail-on-multiyear-aftereffects.html
…you would find that my presentation and description in this post is confirmed by the papers and by my presentations of the many coupled ocean-atmosphere processes that take place during ENSO events.
You wrote, “The period 1945-76 saw very few El Nino events and a progressive increase towards La Nina conditions. That sustain period of La Nina conditions wasn’t reflected in the very next El Nino, which according to Bob should have been huge.”
I don’t believe I wrote or implied that every strong La Nina event or a sustained period of La Nina events would generate a huge El Nino, John. And I believe I was quite clear on which specific La Nina events raised tropical Pacific OHC. In the summary, I wrote, The La Nina event of 1973/74/75/76 provided the tropical Pacific Ocean Heat Content necessary for the increase in strength and frequency of El Nino events from 1976 to 1995. The 1995/96 La Nina furnished the Ocean Heat Content that served as fuel for the 1997/98 El Nino. And the 1998/99/00/01 La Nina recharged the tropical Pacific Ocean Heat Content after the 1997/98 El Nino, returning it to the new higher level established by the La Nina of 1995/96.
So this part of your comment either expresses your misunderstanding of what was written or expresses your intentional misrepresentation of it.
Also, the data appears to contradict your statement, John. If you were to examine the NINO3.4 SST anomaly data I presented above in Figure 17…
http://i46.tinypic.com/29krqd2.png
…for the period of 1955 to 1975, you would find that the moderate to strong La Nina events were in fact followed by moderate to strong El Nino events, and that during a “sustained period of La Nina conditions”, such as the one from the late 1950s to the mid 1960s, the La Nina conditions (negative anomalies) were weak and so was the El Nino that followed.
You wrote, “And finally I note that Bob wrote his piece without even one mention to last year’s JGR paper that I wrote with two colleagues and in which we discussed how ENSO activity very largely drives subsequent global temperatures.”
There were hundreds of papers I could have cited, John. Also, it would have been nice if you had provided a link to the July 2009 paper you referred to: “Influence of the Southern Oscillation on tropospheric temperature”…
http://ruby.fgcu.edu/courses/twimberley/EnviroPhilo/InfluenceSoOscillation.pdf
That way those reading your comment wouldn’t have to chase it down on their own.
In short, your paper discusses using the SOI to reproduce global TLT anomalies from the 1960s to present. In your abstract, you wrote, “Change in SOI accounts for 72% of the variance
in GTTA for the 29-year-long MSU record and 68% of the variance in GTTA for the longer 50-year RATPAC record.” Where GTTA is global tropospheric temperature anomalies. I, on the other hand, have shown that global temperature anomalies using HAdCRUT data can be reproduced as a function of NINO3.4 SST anomalies for the period of the 1910s to present, if one assumes that the global oceans integrate the effects of ENSO:
http://bobtisdale.blogspot.com/2009/01/reproducing-global-temperature.html
In other words, had you used NINO3.4 SST anomalies and global surface temperatures for your study, you may have been able to extend your research back for another four decades and you may have captured more of the rise in global temperatures for the longer time period.
You concluded with, “I’m aware that Bob doesn’t seem to like the SOI calculated according to the Troup system, and I wonder why.”
Really? Have I written that I don’t “seem to like the SOI” somewhere? Please cite your source.
Bob Tisdale –
Looking at the image/pic above. Is there anything that has appeared telling about changes in the jet streams for the period you are studying? (Sorry if I missed something already addressed, still on 1st cup of eyeopener.)
Paul Vaughan: Thanks for the links to the LOD data. Please feel free to post it in your comments during any subsequent threads. Note the subject matter of this post. It’s very specific. In no way have I attempted to explain every facet of ENSO. It’s impossible. Also, the LOD/ENSO relationship appears to be hotly contested, so if I were to include it in posts, it would draw from the points I try to make.
You wrote, “Strongly disagree with this portrayal Bob,” in response to my comment about the PDO being an aftereffect of ENSO.
We can disagree, Paul, I have no problem with that, but in another reply, I posted links to four papers that discussed that the PDO and the basin-wide patterns in the Pacific are aftereffects of ENSO:
Newman et al (2003):
http://www.cdc.noaa.gov/people/gilbert.p.compo/Newmanetal2003.pdf
Zhang et al (1997):
http://www.atmos.washington.edu/~david/zwb1997.pdf
Evans et al (2001):
http://iceman2.umd.edu/www/preprints/pdv.pdf
Shakun and Shaman (2009):
http://www.leif.org/EOS/2009GL040313.pdf
I’ve also written two posts that address many of your concerns, and I believe you’ve read at least one of those already, but here they are for those who may be unfamiliar with them:
http://bobtisdale.blogspot.com/2009/04/misunderstandings-about-pdo-revised.html
AND:
http://bobtisdale.blogspot.com/2009/05/revisiting-misunderstandings-about-pdo.html
The first one was also co-posted here at WUWT, for those who want to run through the comments:
http://wattsupwiththat.com/2009/04/28/misunderstandings-about-the-pacific-decadal-oscillation/
Last, you wrote regarding the effects of ENSO on local climate, “The 2004 event stands out as an example of when N3.4 does not tell the right story locally.”
Erl had probably noted that regional responses to ENSO events varied between El Nino events well before El Nino Modoki were defined and well before the regional effects of El Nino Modoki were isolated from traditional El Nino events. And as someone whose winery is strongly impacted by El Nino events, Erl could probably note differences between one traditional El Nino event and another and between one El Nino Modoki and another. But my reply was to Erl’s specific question about tropical SST anomalies and NINO3.4 SST anomalies.
Regards
tallbloke (02:18:20) :
And that’s where I cheated a little some will say. There’s a low latitude eclipse in october 76 but since that’s so late in the year I didn’t give it a low lat score. Somewhere around zero would be more correct.
Re: John McLean (23:01:53)
Thanks for dropping by and sharing valuable notes.
–
Bob, the links you need are:
1) EOP (Earth orientation parameters):
http://hpiers.obspm.fr/
2) SSD (solar system dynamics):
http://ssd.jpl.nasa.gov/?horizons
There’s a learning curve for both.
In the past I have disagreed with you regarding your portrayal of SOI & PDO relations. I continue to do so – more strongly now since you continue to ignore EOP & SSD.
Investigations of terrestrial oscillations involving EOP & SSD are not necessarily “competing” with all of your views – one option I can suggest is regarding them as “complementary”.
When investigating multivariate phase-relations, the interesting features are the mismatches. If all the wiggles matched, we’d have nothing to learn and there would be no need for discussion – indeed we’d simply have redundant variables that could be tossed away without loss of info. From the timescale-specific phase-mismatches between LOD, QBO, GLAAM, SOI, NAM, SAM, etc. we can learn about SOI priming, triggering, etc.
Consider that the solar system is gently rocking the anomaly tendencies one way or another from the central limit (of chaotic & stochastic components) in a manner that integrates meaningfully at some timescales. The notion that the trigger (rocker) does little if the system isn’t primed (piled WPWP) is very useful. Explaining phase-contrast residuals might be easier than most have imagined.
–
tallbloke (13:44:10) “[…] Paul Vaughan warns there may be a counfounding issue with a similar length solar cycle.”
Solar system – (not solar).
–
lgl, one way or another an objective calculation of the eclipse curve is needed. I’ll keep watching in case you turn up some useful links. I want to pursue this – and efficiently. Thanks for sharing the graphs to direct our attention.
The 2010 El Nino, which really wasn’t, it didn’t reach the SA west coast to be baptized as such:
http://www.elnino.noaa.gov/
Not even NOAA could make it happend.
Paul Vaughan (11:28:08) :
The link I gave should be correct so maybe there’s a server problem. I saved a copy long ago I can e-mail you if you like (if my mailsystem accepts 20 MB)
Here’s another curve back to 1930, as objective as I’m able to 🙂
http://virakkraft.com/hadcrut-eclipse.png
Paul Vaughan: You wrote, “In the past I have disagreed with you regarding your portrayal of SOI & PDO relations. I continue to do so – more strongly now since you continue to ignore EOP & SSD.”
It could be that you and I have a different perspective on the PDO and its variability. Let’s look at the curves created by subtracting the different NINO indices (NINO1+2, NINO3, NINO3.4 & NINO4) from the PDO available through JISAO. The NINO datasets are based on HADISST.
http://i50.tinypic.com/1zbv1tz.png
The differences present the decadal variability that I’m sure you’re aware of, and upon which you may base your opinions. The JISAO PDO data is the leading PC of North Pacific SST anomalies North of 20N. JISAO uses three SST datasets spliced together to create the PDO: UKMO Historical SST for 1900-81, OI.v1 for 1982 to 2001, and OI.v2 for 1983 to present. Does the difference between the datasets impact the curve? Dunno. UKMO (Met Office) SST data may have ended in 1981. It surely has been replaced by HADSST and HADSST2. But that’s really not the point I’m trying to make or illustrate.
There are, of course, other SST datasets. The NCDC created a number of versions of their ERSST before arriving at the present version, ERSST.v3b. And the NCDC publishes PDO data using the same methods used by JISAO.
ftp://eclipse.ncdc.noaa.gov/pub/ersstv3b/pdo/pdo.1854.latest.situ.v3b.ts
There are differences between the two PDO datasets, which are visible by subtracting the ERSST.v3b PDO data from the JISAO PDO data.
http://i46.tinypic.com/sq73ty.png
And there are differences between Hadley Centre and NCDC versions of NINO SST data. This can be illustrated as HADISST NINO3.4 SST anomalies minus ERSST.v3b NINO3.4 SST anomalies.
http://i46.tinypic.com/euj4uc.png
The differences between the ERSST.v3b version of the PDO data and the various ERSST.v3b NINO Indices create curves that in no way resemble the JISAO/HADISST versions.
http://i48.tinypic.com/jtrsqu.png
The differences between the versions of the PDO Minus NINO data suggest to me that there may not be the multidecadal divergences between PDO and ENSO that many believe exist. In other words, the JISAO/HADISST version creates a convenient curve that people like.
Also, I while back on a thread here at WUWT I explained how the PDO pattern was created by ENSO, and if I can dig it up I’ll throw it here for you.
Regards
Re: Bob Tisdale (18:18:39)
Thanks for the elaboration Bob. It helps clarify that technicalities & definitions can drive misunderstandings.
We are indeed focused on different aspects of related phenomena – not a bad thing – complementary as I see it.
Thanks to all who have participated in this thread – the various links provided by contributors have been useful.