Typical (Average) El Nino, Traditional El Nino, and El Nino Modoki Events
Guest Post by Bob Tisdale
Recently, there have been a number of posts around the blogosphere about the current El Nino or about Sea Surface Temperatures (SST). Accompanying them are predictions by the authors of those posts or by commenters of a pending La Nina event. But the “typical” El Nino event is not followed by a La Nina event. Also, the current 2009/10 El Nino event is an El Nino Modoki; that is, simply, the area with elevated SST anomalies is located more towards the center of the tropical Pacific than a traditional El Nino event; and few La Nina events follow El Nino Modoki.
A number of months ago I noticed some of my visitors arrived from Google searches of “typical El Nino” or “average El Nino”. I prepared this post for them back then but got sidetracked and never posted it.
This post looks at the development and decay of the average El Nino, of the average traditional El Nino, and of the average El Nino Modoki. I’ve also segmented the data into two periods, before and after 1979 to illustrate the change in development and strength of El Nino events. Last, as references, are spaghetti plots of the development and decay of all El Nino events since 1950 (excluding the current El Nino, since it’s not complete). The post could also be used by those bloggers who like to make predictions or by those wanting to see whether prognostications have any basis in history.
THE AVERAGE EL NINO
Figure 1 illustrates the development and decay of the average El Nino event for the period of 1950 through 2007. It starts in January of the development year and ends in December of the following (decay) year. To create the graph, I averaged the SST anomaly (ONI) values for the 24 months associated with each official El Nino event identified on the CPC’s Oceanic Nino Index (ONI) webpage:
http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ensoyears.shtml
The average El Nino reaches the +0.5 deg C threshold of an El Nino in late May, peaks in December, then quickly decays until it drops below the +0.5 deg C El Nino threshold in mid March. The SST anomalies of the average El Nino do drop below zero, but during the following ENSO season they do not cross the -0.5 deg C threshold for a La Nina event.
http://i39.tinypic.com/k3vuvo.png
Figure 1
BEFORE AND AFTER 1979
The frequency and magnitude of ENSO events changed about 1976. Between the mid-1940s and the mid-1970s, La Nina events dominated (with a period of El Nino dominance in the 1960s), and after, El Nino events were dominant. This can be illustrated with a long-term graph of NINO3.4 SST anomalies smoothed with a 121-month filter, Figure 2.
http://i43.tinypic.com/33agh3c.jpg
Figure 2
But studies such as Trenberth et al (2002) divide the data into periods before and after 1979, based on the development of El Nino events, so I’ve divided the data in this post at 1979. (The 1976/77 event was a weak traditional El Nino, and the 1977/78 El Nino was a weak El Nino Modoki.) Link to Trenberth et al (2002) “Evolution of El Nino–Southern Oscillation and global atmospheric surface temperatures”:
http://www.cgd.ucar.edu/cas/papers/2000JD000298.pdf
The average SST anomalies of the El Nino events before and after 1979 are shown in Figure 3. It comes as no surprise that El Nino events after 1979 are stronger and last longer than those before the cutoff year. Still, even in more recent decades, the average El Nino is not followed by a La Nina.
http://i40.tinypic.com/2wpto8w.png
Figure 3
TRADITIONAL EL NINO VERSUS EL NINO MODOKI
Central Pacific versus Eastern Pacific El Nino events are discussed in a number of recent papers. Ashok et al (2007) “El Nino Modoki and its Possible Teleconnection”… https://www.jamstec.go.jp/frcgc/research/d1/iod/publications/modoki-ashok.pdf
…provides an equation that can be used to identify El Nino Modoki:
“EMI= [SSTA]A-0.5*[SSTA]B-0.5*[SSTA]C …(1)
“The square bracket in Equation (1) represents the area-averaged SSTA over each of theregions A (165E-140W, 10S-10N), B (110W-70W, 15S-5N), and C (125E-145E, 10S-20N), respectively.”
Ashok et al further describe the basis for their selection of El Nino Modoki events: “Based on the time series of the EMI shown in Figure 4a, we have identified seven typical El Niño Modoki events that lasted from boreal summer through boreal winter, peaking in one of these seasons (seasonal standard deviations for boreal summer and winter are 0.5ºC and 0.54ºC respectively). These typical El Niño Modoki events occurred in 1986, 1990, 1991, 1992, 1994, 2002, and 2004. Additionally, we identified a typical El Niño Modoki during the boreal winter of 1979-80 that lasted through the summer of 1980, though its amplitude fell below the threshold of 0.7 σ by then.” And they clarify with the footnote, “We call an El Niño Modoki event ‘typical’ when its amplitude of the index is equal to or greater than 0.7 σ, where σ is the seasonal standard deviation.”
Ashok et al appeared to use two definitions of an El Nino Modoki: first, the average of boreal summer through boreal winter for most events, and, second, the average of the boreal winter for the 1979 event. Using the average boreal summer through winter (June through February) El Nino Modoki Index and the boreal winter El Nino Modoki Index, Figure 4, as references, I’ve identified the typical El Nino Modoki events before 1979 (based primarily on the boreal winter data when they conflict). These along with traditional El Nino events are shown in Table 1, as are the breakdown of El Nino events after 1979.
http://i40.tinypic.com/16kc3kg.png
Figure 4
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http://i39.tinypic.com/24e7v2t.png
Table 1
Note 1: El Nino Modoki events identified by Ashok et al that do not qualify as official El Nino events on the ONI Index have been excluded.
Note 2: As illustrated in Table 1, there were more El Nino Modoki before 1979 than after, yet in press releases we’re advised that El Nino Modoki events are new, and that this NEW TYPE is resulting in a greater number of hurricanes with greater frequency and more potential to make landfall.” Refer to the press release…http://media-newswire.com/release_1094000.html…for the Hye-Mi Kim, et al (2009) paper “Impact of Shifting Patterns of Pacific Ocean Warming on North AtlanticTropical Cyclones”:
http://www.sciencemag.org/cgi/content/abstract/325/5936/77
The press release describes El Nino Modoki as “new” more than once. The “newness” of El Nino Modoki was also contradicted by data in my July 6, 2009 post There Is Nothing New About The El Nino Modoki.
Figure 5 compares the average El Nino Modoki and Traditional El Nino event since 1950. The typical Traditional El Nino is stronger than the El Nino Modoki and it results in a La Nina event, where the typical El Nino Modoki decays to a neutral SST anomaly of ~0.
http://i44.tinypic.com/5pkhn8.png
Figure 5
MORE COMPARISONS
Figures 6 through 9 provide further comparisons of El Nino Modoki and Traditional El Nino events before and after 1979. I won’t discuss these individually, other than to call your attention to the comparison of El Nino Modoki and Traditional El Nino events prior to 1979, Figure 8. Note that El Nino Modoki events were stronger and their durations were longer than Traditional El Nino events.
http://i41.tinypic.com/qz222u.png
Figure 6
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http://i41.tinypic.com/bk4ux.png
Figure 7
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http://i42.tinypic.com/dqzon.png
Figure 8
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http://i39.tinypic.com/elcfa0.png
Figure 9
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COMPARISONS OF INDIVIDUAL EL NINO EVENTS
Figure 10 compares the ONI SST anomalies for the 8 Traditional El Nino events from 1950 to 2007. Dashes are used to identify the El Nino events before 1979. Of the 8 Traditional events, only two El Nino events did not transition into La Nina events. The 1976/77 El Nino was followed by the 1977/78 El Nino Modoki.
http://i44.tinypic.com/jtxvg9.png
Figure 10
And the 1951/52 El Nino was not followed by a La Nina. The 1951/52 El Nino is also anomalous in that it peaks before the typical El Nino peak months of November, December, and January. However, looking at maps of ICOADS SST anomaly data (the basis for the Hadley Centre and NCDC’s SST data) for the tropical Pacific for October through December 1951 and for January 1952, Figure 11, we can see that there were few to no SST readings during those months in the NINO3.4 region (and most of the tropical Pacific for that matter), so the 1951/52 El Nino data could be considered suspect. (Always keep in mind that much of SST data before the eras of buoys and satellites are infilled.)
http://i42.tinypic.com/qod3bq.png
Figure 11
And Figure 12 is a comparison of the 10 El Nino Modoki events. I’ve also identified the earlier events with dashes. Of the 10 El Nino Modoki, only 2 events transitioned into La Nina events, the 1963/64 and 1994/95 El Nino events. The SST anomalies during the ENSO season following the 2004/05 El Nino dipped below the La Nina threshold, but did not remain there long enough to be considered an official La Nina.
http://i44.tinypic.com/72deeq.png
Figure 12
CLOSING COMMENT
Will a La Nina follow the 2009/10 El Nino? Considering that only 2 of 10 El Nino Modoki events since 1950 were followed by La Nina events, the odds are against it. But nature does provide surprises.
SOURCES
The ONI data is available through the NOAA CPC webpage:
http://www.cpc.noaa.gov/products/analysis_monitoring/ensostuff/ensoyears.shtml
The HADISST SST anomaly data used for the El Nino Modoki graph, and the ICOADS data used for the tropical Pacific SST maps are available through the KNMI Climate Explorer:
http://climexp.knmi.nl/selectfield_obs.cgi?someone@somewhere
I also used the KNMI Climate Explorer to create the maps.
Is there a way to assess the effects of a weak or strong sunspot cycle on strength and/or duration of El Niño events? Since there is likely to be a lag time of indefinite amount, I suggest using a non-parametric correlative analysis, such as grading. For example, if a sunspot cycle is weak, average, or strong, give it a 1,2 or 3. For the other way of gauging strength, length of cycle, this may give a better result using duration years of the cycle. The trick would be to find out the lag time, since it must take a while for maxima to influence a decrease in cloud cover that concomitantly increases heat which then gets stored near Japan and released later in an El Niño event.
Ulric Lyons says:
May 2, 2010 at 10:54 am (John Finn comment)
Correction: “while even numbered cycles were low during LIA, have more recently become stronger”
should have said; were higher during LIA, became weaker ( from early 1800`s) until recently.
Bob Tisdale says:
May 2, 2010 at 9:30 am
Am I right that etudiant had it the wrong way around – re. your recent posting on heat discharge and recharge associated with the ENSO cycle. You explained that it is the La Nina that recharges ocean heat (at least Pacific) and conversely the el Nino that discharges heat. So the long term ocean heat trend results from the balance of the two processes.
Kevin Trenberth’s recent “dude – where’s my heat?” article about the “missing” heat presented a graph showing falling ocean heat content while rising radiative budget due to CO2.
http://www2.ucar.edu/news/missing-heat-may-affect-future-climate-change
It makes sense in the context of your ENSO heat exchange description, that in a period dominated by el Nino, such as the last 30 years or so, that heat discharge should exceed recharge and thus OHC should be on a downward slope. As Trenberth asserts and other sources of data also support – OHC is indeed declining over the last decade or two. Or maybe not? I guess OHC globally is tricky to assess so there are different assessments out there. What is your take on this? (Douglass and Knox also concluded that global OHC is currently declining.)
R. Gates says:
May 2, 2010 at 11:17 am
Don’t take it personally. It’s a philosophical/workplace question that is found in many trades.
It takes many forms:
Never let the machine run you, you run the machine.
Do you run the xxxx, or does xxxx run you?
In the climate business, too many are running off on a model output that seems right, but the observational data walks away from. In effect, the models are running them in circles. What should be happening, R. Gates, is that the climatists should be running the errant models into the recycle bin.
Without the models being run independently, there is no way to verify the output other than recent events agreeing or disagreeing. When an untested/unverified model has to have corollaries attached to it in a never-ending process, the handwriting is already on the wall.
Enneagram says: May 2, 2010 at 8:57 am
Though we are in “interesting times”, in a minimum, so here you can find el Nino data from 1525:
http://www.scribd.com/doc/30810082/Ninos
‘Enneagram’ that is a very fascinating and telling list of the El Nino events. If delta T for intense El Nino is plotted along time scale, then it is evident the same periodicity as one in the long term solar cycle spectrum or the Sunspot anomaly.
http://www.vukcevic.talktalk.net/LFC22.htm
Hello Bob.
Distinguishing between ‘normal’ El Nino and the ‘Modoki’ variety seems to be a useful approach.
Going by Fig 4 it looks like the Modoki index is higher during a cooling spell than it is during a warming spell.
Would you go along with that ?
If so, I wonder whether a reduced flow of energy from ocean to air is the factor that generally results in a weakened Modoki version of the standard El Nino.
As regards any subsequent La Nina do you see any corresponding change in the nature of La Nina events that follow a Modoki as against those that follow the standard El Nino.
I ask because whatever causes the El Nino to manifest itself in a slightly different form could also do the same to any subsequent La Nina.
Where I am going with this query is to try and ascertain whether reduced/increased rates of energy transfer from the oceans affect the forms of both El Nino and La Nina as part of a general cooling/warming trend.
It makes sense that for a trend towards either warming or cooling then both El Nino and La Nina SST patterns might be affected.
phlogiston: You wrote, “It makes sense in the context of your ENSO heat exchange description, that in a period dominated by el Nino, such as the last 30 years or so, that heat discharge should exceed recharge and thus OHC should be on a downward slope. As Trenberth asserts and other sources of data also support – OHC is indeed declining over the last decade or two.”
The ENSO discharge and recharge taking place in the tropical Pacific contributes to global OHC, but the biggest contributor to the decline in OHC in recent years is the North Atlantic. It’s also the biggest contributor to the rise for the prior few decades. My complaint with the new Trenberth study is that, on one hand, he’s claiming that the warm water is being subducted and lost from the record and will return in future decades, but he neglects to mention how much of the recent rise is the return of warm waters from a previous AMOC “cycle”.
phlogiston May 2, 2010 at 11:46 am: You italicized, “Am I right that etudiant…” and appeared to the attribute it to me. Just a clarification. I didn’t write what you italicized.
Stephen Wilde: You asked, “Going by Fig 4 it looks like the Modoki index is higher during a cooling spell than it is during a warming spell. Would you go along with that ?”
Assuming you’re calling the period before 1979 the cooling spell and the period after 1979 to warming spell, I’ll clarify, the El Nino Modoki index may be higher in the early period, but El Nino Modoki EVENTS are stronger during the period after 1979 (the warming spell). Refer to Figure 7:
http://i41.tinypic.com/bk4ux.png
You asked, “As regards any subsequent La Nina do you see any corresponding change in the nature of La Nina events that follow a Modoki as against those that follow the standard El Nino.”
I haven’t looked, but there were only two La Nina events following El Nino Modoki events, which really isn’t enough to determine a pattern:
http://i44.tinypic.com/72deeq.png
Ashok et al does discuss La Nina Modoki, though:
https://www.jamstec.go.jp/frcgc/research/d1/iod/publications/modoki-ashok.pdf
Re the naming of neutral phases of the ENSO, I’ve always been partial to “La Nada”.
Tenuc: You asked, “Do prolonged neutral El Niño conditions result in a greater loss in total ocean energy than the other the other events?”
An El Nino event releases more heat than normal from the tropical Pacific, so I’d have to say no.
You asked, “Is there a link between El Niño strength and the SH polar vortex?”
I haven’t studied it. Sorry.
Bob Tisdale says:
May 2, 2010 at 8:37 am
Bob,
The majority of the warmer water in the central Pacific should be north of the equator till next autumn, its whether it will maintain warm by the time it returns that will decide.
Ulric Lyons: You asked, “How much lattitude has this?”
I’ve searched for the latitudes a couple of times but never found the answer.
Mr. Tisdale,
How dare you use historical data to actually come up with a prediction. What’s next, the sky is blue and the grass is green? 😉 Anyway, nice work.
melinspain says:
May 2, 2010 at 5:14 am
Is it possible to spell correctly “El Niño” and “La Niña”? Thanks
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Some of our keyboards do not allow accents so to get the correct spelling it takes cut and past of yours. I have to do that for french all the time.
REPLY: one way is to use keyboard keys Alt + 0241 = ñ (241 in the numeric keypad) – Anthony
etudiant says:
May 2, 2010 at 6:55 am
Thank you Bob for a most helpful overview.
I’m very impressed by the substantial Sea Surface Temperature increase (about 0.2*C) shown in Fig 3.
That indicates an enormous amount of heat added in the more recent Nino events.
As such, this data seems to me the most robust evidence of global warming yet presented.
Is there anyone you would recommend who has done comprehensive ocean heat content measurements that are publicly available and as intelligible as your Nino/Nina work?
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Take it a step further. As water warms it dissolves less CO2 (out gases) and therefore a warming of the oceans by 2 degrees would CAUSE an increase in CO2. The next question is where is the heat actually coming from. Willis had an interesting post here. http://wattsupwiththat.com/2009/06/14/the-thermostat-hypothesis/
Bob Tisdale says:
May 2, 2010 at 2:23 pm
Ulric Lyons: You asked, “How much lattitude has this?”
I’ve searched for the latitudes a couple of times but never found the answer.
Here:
http://weather.unisys.com/surface/sst_anom.html
http://www.vukcevic.talktalk.net/LFC19.htm
It reached to Portugal´s Madeira island where it provoked floods.
Bob Tisdale says:
May 2, 2010 at 12:53 pm
I messed up the italics – sorry for giving the wrong impression! It was all me – there was no quote from you.
aurbo says:
May 2, 2010 at 1:52 pm
Re the naming of neutral phases of the ENSO, I’ve always been partial to “La Nada”.
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I second the motion, all in favor say Aye….. ROTFLMAO
Bob Tisdale says:
May 2, 2010 at 12:45 pm
“The ENSO discharge and recharge taking place in the tropical Pacific contributes to global OHC, but the biggest contributor to the decline in OHC in recent years is the North Atlantic. ”
Yes indeed this new ocean that we have since the Triassic makes things more complex and interesting. I guess that the Norwegian sea downwelling is a dominant factor in the thermo-haline circulation (THC). I do have trouble with the idea – that Trenberth appeals to – that warm water sinks to the bottom and joins THC, and represents “warming in the pipeline”. Downwelling as I understand it occurs when seawater is close to or at freezing point, and the low temperature combined with increased salinity due to ice formation, give the unfrozen seawater a high enough density to sink down into the sub-thermocline depths. If this water is slightly warmer it would not sink. But I dont have facts and figures to prove this. However it might be that the volume and pattern of downwelling could vary, rather than the temperature of the downwelled water, than this could provide linkage between climate variation and THC variation over century timescales.
(hope I got the italics right this time!)
REPLY: one way is to use keyboard keys Alt + 0241 = ñ (241 in the numeric keypad) – Anthony
Thanks for the tip Anthony. Unfortunately it does not work on this computer. Hubby has a Unix system on it. Linux maybe
melinspain: You requested, “Is it possible to spell correctly ‘El Niño’ and ‘La Niña’?”
I’ve just added “El Niño” and “La Niña” to the autocorrect in MS Word, so the spelling will be correct in future posts.
Regards
I am no authority but I would contend that these terms have been used enough in the English language to qualify as English words of Spanish origin rather than Spanish words. And since English vowels don’t wear hats, none are needed. It is a longstanding tradition among anglophones to steal things from other languages and misuse them as we see fit. It is just our way.
I meant to say that our letters don’t wear hats. And I don’t mean to disparage the fashions of other languages but merely point out that English letters like to go au naturel. I suppose that last bit should have been italicized but then that brings up a whole other annoying issue.
Bob,
Thank you for the helpful clarification.
Your concept, that heat accumulates during Nina phases and is dissipated during Nino episodes, is very plausible. My query was because the more recent Ninos show a substantially higher SST than previous, indicating greater heat accumulation in recent decades.
The NOAA data referenced by R Gates likewise shows a large increase since 1990 in ocean heat content.(more than 10*23 Joules for the top 700 meters).
The Trenberth chart you posted also shows continued increase in ocean heat, albeit at a substantially declining rate, as opposed to the steeper increase expected by the AGW models.
In your model, these data should result in more frequent as well as longer Ninos, to dissipate the increased heat, pretty much as we are seeing.
But I’m still puzzled where the extra heat is coming from.