From the University of Hawaii ‑ SOEST:
Climate researchers discover new rhythm for El Niño
El Niño wreaks havoc across the globe, shifting weather patterns that spawn droughts in some regions and floods in others. The impacts of this tropical Pacific climate phenomenon are well known and documented.
A mystery, however, has remained despite decades of research: Why does El Niño always peak around Christmas and end quickly by February to April?
Now there is an answer: An unusual wind pattern that straddles the equatorial Pacific during strong El Niño events and swings back and forth with a period of 15 months explains El Niño’s close ties to the annual cycle.
This finding is reported in the May 26, 2013, online issue of Nature Geoscience by scientists from the University of Hawai’i at Manoa Meteorology Department and International Pacific Research Center.
“This atmospheric pattern peaks in February and triggers some of the well-known El Niño impacts, such as droughts in the Philippines and across Micronesia and heavy rainfall over French Polynesia,” says lead author Malte Stuecker.
When anomalous trade winds shift south they can terminate an El Niño by generating eastward propagating equatorial Kelvin waves that eventually resume upwelling of cold water in the eastern equatorial Pacific. This wind shift is part of the larger, unusual atmospheric pattern accompanying El Niño events, in which a high-pressure system hovers over the Philippines and the major rain band of the South Pacific rapidly shifts equatorward.
With the help of numerical atmospheric models, the scientists discovered that this unusual pattern originates from an interaction between El Niño and the seasonal evolution of temperatures in the western tropical Pacific warm pool.
“Not all El Niño events are accompanied by this unusual wind pattern” notes Malte Stuecker, “but once El Niño conditions reach a certain threshold amplitude during the right time of the year, it is like a jack-in-the-box whose lid pops open.”
A study of the evolution of the anomalous wind pattern in the model reveals a rhythm of about 15 months accompanying strong El Niño events, which is considerably faster than the three- to five-year timetable for El Niño events, but slower than the annual cycle.
“This type of variability is known in physics as a combination tone,” says Fei-Fei Jin, professor of Meteorology and co-author of the study. Combination tones have been known for more than three centuries. They where discovered by violin builder Tartini, who realized that our ear can create a third tone, even though only two tones are played on a violin.
“The unusual wind pattern straddling the equator during an El Niño is such a combination tone between El Niño events and the seasonal march of the sun across the equator” says co-author Axel Timmermann, climate scientist at the International Pacific Research Center and professor at the Department of Oceanography, University of Hawai’i. He adds, “It turns out that many climate models have difficulties creating the correct combination tone, which is likely to impact their ability to simulate and predict El Niño events and their global impacts.”
The scientists are convinced that a better representation of the 15-month tropical Pacific wind pattern in climate models will improve El Niño forecasts. Moreover, they say the latest climate model projections suggest that El Niño events will be accompanied more often by this combination tone wind pattern, which will also change the characteristics of future El Niño rainfall patterns.
Citation: Stuecker, M. F., A. Timmermann, F.-F. Jin, S. McGregor, and H.-L. Ren (2013), A combination mode of the annual cycle and the El Niño/Southern Oscillation, Nature Geoscience, May 26 online publication at http://dx.doi.org/10.1038/ngeo1826.
h/t to Dr. Leif Svalgaard
Doesn’t seem to me from the information here that a “cause” has been found. Perhaps a correlating event, but that’s about it…
It doesn’t correlate to anything since the frequency is wrong. What is new is that they have managed to get a El Nino “type” oscillation out of a model.
The “cause” is the lunar declinational atmospheric and ocean tides at culmination come in and out of phase with the solar declinational tidal effects when the culmination angle of both are close to the same angle. as the 18.6 year cycle of the extent of the lunar culmination varies, the relationship is strengthened or weakened as the two effects go in and out of phase. The lunar declinational angle at culmination is now less than 20.5 degrees and decreasing for the next couple of years so the effects are going to be minimal for several years until it returns back toward 23 degrees when the effects is optimal for El Nino production alternating with La Nina effects with the additional heliocentric interactions of the outer planets, and the procession of the nodes of the moon, being confounding effects that make the pattern seem rather random looking.
So those above who hint that there is a Juniper? or Saturn or lunar nodal effect in the mix will not find the answer from only one variable being considered. The strongest effect is from the declinational tidal interactive effects from both the sun and the moon.
We got the outbreak of tornadoes as the combined sun/lunar declinational tidal effects in the atmosphere when into phase as the moon was coming back from Maximum North culmination till crossing the equator. Now that it has reached Maximum South yesterday (the 26th) and is pulling in a surge of secondary tidal bulge effects across the upper mid-west, we are having a derecho streaming across Iowa into Illinois as a result. Much like last time;
http://research.aerology.com/severe-weather/derecho-storm-seen-from-space/
I’ve just checked the formula and I think the paper has got it wrong , as I did above by following their logic.
They are making the error of confusing the audible beat frequency with actual frequency. This is explained in Wikipedia page I linked above. The REAL frequency is half what they calculate. The ear can only hear acoustic intensity so the “beats” we hear are twice as fast as the actual oscillation.
So I double my previous results to give 20 and 30 months ( twice their 15m)
Now 30m is 2.5 years
http://climategrog.wordpress.com/?attachment_id=278
Looks like this deserves a closer look .
@richard Holls
the years of the major VE force eruptions I used above : 1883 1902 1912 1963 1982 1991
All those dates differ by 19 or 9 years. cf “18.6 year cycle of the extent of the lunar culmination”
From the snippet we get at the doi link provided I find this acompanying figure 2:
“Frequency is abbreviated to f. To illustrate the PC2 combination tone frequencies, PC1 was shifted to 1−f (dashed blue) and 1+f (dashed green) and scaled by a factor 1/3. Grey rectangles indicate the near-annual combination tone frequen…”
I need to see the paper to be sure and see what they actually did to get their modelled results but it appears they did use the wrong calculated result for the beat pattern of 1 and 5 years.
I like the attempt to see with greater detail. Originally (I’m talking forty years ago,) I heard talk of the El Nino versus a sort of “regular state.” Then there was an El Nino versus a La Nina versus a regular state. Now they are starting to speak of various types of El Nino and La Nina, based on where the greatest anomalies are centered, versus a regular La Nada state.
I think they need to drop the idea of any sort of “regular state.” It is a bit like talking about the “average inflation” of our lungs; it is a midpoint we pass but never stay at.
The writer adopts a sort of sensationalist tone, beginning, “El Niño wreaks havoc across the globe…” and moving on from there. Perhaps it is just a writer’s ploy to capture our attention, however it distracts me. It is like saying “Rain wreaks havoc across the globe,” in that it takes a normal, natural and necessary phenomenon and toots tons of trumpets.
All over the world the weather shifts from sunny spells to rainy spells and back again. It is as natural as breathing. My garden needs both. What grabs the headlines is occasions when the cycle hesitates at one extreme or another, (floods and droughts, which mess up my garden.)
I doubt we will ever control the weather, however understanding the detail and nuances of the cycles allow us to plan better: When to water gardens and when not to; when to release water from reservoirs and when to hold water back, and so on. Therefore seeing with greater detail is beneficial to us all, and well worth funding, however a lot of the hoop-la is, to be frank, just a big waste of time, unless you’re selling papers or seeking grants.
This idea does not come close to explaining how or why the balance between nino and nina events (the ENSO index) varies over a sixty year cycle…
The abstract for the Stuecker et al (2013) paper includes:
“El Niño events typically peak in the boreal winter, but the mechanism governing this phase synchronization7 is unclear.”
In reality, the mechanism governing it is pretty obvious if you look at sea surface temperatures and not anomalies. During an El Niño, the sea surface temperatures of the Eastern Equatorial Pacific take on the seasonal cycle of the western tropical Pacific, because the equatorial counter current in the Pacific has strengthened and is carrying more warm water than normal from west to east. And during the La Niña, the normal seasonal cycle in the eastern equatorial Pacific is simply exaggerated. Pretty simply actually. Refer to the post:
http://bobtisdale.wordpress.com/2013/03/19/why-do-el-nino-and-la-nina-events-peak-in-boreal-winter/
Regards
GlynnMhor says:
This idea does not come close to explaining how or why the balance between nino and nina events (the ENSO index) varies over a sixty year cycle…
==
No, but they’re looking in the right direction rather than brushing it all off as AGW + stochastic .
It seems “5” represents a fixed ENSO frequency which is then added to the annual variations giving a beats interference pattern. Their 1-f , 1+f would be correct if they are just referring to the intensity of this crosswind , though there should presumably be a reversal in direction or else some physical explanation is needed as to what is varying at half the frequency and producing winds in one direction only. I’d like to see the details they have on this 15m wind pattern.
I’m encouraged by the approach. Climate is full of neg. feedbacks and natural oscillations, there is far too little of this kind of research that seeks to identify and explain the interactions rather than dismissing everything as “random” as an excuse for not looking.
Its hard to see what they are saying here in this study.
Generally, I think the Trade Winds are the driver of the ENSO.
http://s17.postimg.org/noobqikhr/Trades_ENSO_Apr_2013.png
And this very close relationship extends all the way back into record using the ESRL Renalysis2 dataset going back to 1871.
http://s22.postimg.org/460b6n5hd/Trades_ENSO_1871.png
But the ultimate driver of the winds and the ENSO is the temperture of the water itself (which has various circulatory patterns but one that is not recognized as important in the Equatorial undercurrent where the ocean actually flows backwards in the Pacific from the western side to the eastern side at 250 metres depth).
Upper Ocean Temperature anomaly versus the Trade Winds.
http://s18.postimg.org/9w7m5vjkp/Trades_EUOTA_Apr_2013.png
Which then leads to the ENSO being driven by the temperature of the water itself in a self-reinforcing oscillation.
http://s23.postimg.org/6zyemz1cb/ENSO_EUOTA_Apr_2013.png
Data here.
http://www.cpc.ncep.noaa.gov/data/indices/
http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ocean/index/heat_content_index.txt
The abstract for the Stuecker et al (2013) paper includes:
“Here we show, using observational data and climate model experiments, that the nonlinear atmospheric response to combined seasonal and inter-annual sea surface temperature changes gives rise to a near-annual combination climate mode with periods of 10 and 15 months. Specifically, we find that the associated southward shift of westerly wind anomalies during boreal winter and spring triggers the termination8 of large El Niño events.”
I think the tip is the 10 to 15 month periods. Without having read the paper due to the paywall, it looks as though they’ve “discovered” the seasonal (12-month) variations in the strength of the trades (during ENSO-neutral and La Niña) and the seasonal cycle in the westerlies (during El Niños), which are a function of the warmest waters wandering seasonally between the hemispheres, and how ENSO alters the normal 12-month cycle so that it’s 10 to 15 months.
And we’re sure we know which is cause and which is effect? Why is it that there is always so much eureka in climate science (“Now there is an answer” [to the mystery]) that immediately lets you down when you read it.
I like the theory, but this comment is quite interesting, implying there’s more work to be done
“Not all El Niño events are accompanied by this unusual wind pattern” notes Malte Stuecker, “but once El Niño conditions reach a certain threshold amplitude during the right time of the year, it is like a jack-in-the-box whose lid pops open.”
Jean Meeus says:
May 26, 2013 at 11:06 pm
Thanks – your post convinced me I better brush up on the various definitions for “month”. It seemed so simple when I learned about calendars.
First a couple definitions from http://en.wikipedia.org/wiki/Month
Anomalistic month [time from perigee to perigee]
Synodic month [Time from new moon to new moon]
Unfortunately, I didn’t stop there. 🙂
What you quote from Sera is likely from http://en.wikipedia.org/wiki/Full_moon_cycle which also says:
Later:
[Note 16 x 14 = 224 and 223 / 16 = 13.9375.]
So it appears they use both “basic full moon cycle” (14 lunar months) and “full moon cycle” (slightly less). Sigh, I hate conflicting definitions in science…. And I’m not too keen on fractional approximations except for 355 / 113. What do you call the less than 14 month period?
The rest of the page appears to describe how all this stuff was predicted before computers made it easier. It has a lot of fractional approximations.
Curiously, half of the references are to your articles and books.
Another possibility is discussed in our new paper:
Long-Term Lunar Atmospheric Tides in the Southern Hemisphere
Ian R.G. Wilson and Nikolay S. Sidorenkov
The Open Atmospheric Science Journal, 2013, 7, 29-54 29
http://www.benthamscience.com/open/toascj/articles/V007/TOASCJ130415001.pdf
Apologies for the poor quality of the posted paper as it a e-publication ahead of schedule.
The final paper should appear soon. At least it is free to download.
Abstract
The longitudinal shift-and-add method is used to show that there are N=4 standing wave-like
patterns in the summer (DJF) mean sea level pressure (MSLP) and sea-surface temperature
(SST) anomaly maps of the Southern Hemisphere between 1947 and 1994. The patterns in the
MSLP anomaly maps circumnavigate the Earth in 36, 18, and 9 years. This indicates that they
are associated with the long-term lunar atmospheric tides that are either being driven by the 18.0
year Saros cycle or the 18.6 year lunar Draconic cycle. In contrast, the N=4 standing wave-like
patterns in the SST anomaly maps circumnavigate the Earth once every 36, 18 and 9 years
between 1947 and 1970 but then start circumnavigating the Earth once every 20.6 or 10.3 years
between 1971 and 1994. The latter circumnavigation times indicate that they are being driven by
the lunar Perigee-Syzygy tidal cycle. It is proposed that the different drift rates for the patterns
seen in the MSLP and SST anomaly maps between 1971 and 1994 are the result of a
reinforcement of the lunar Draconic cycle by the lunar Perigee-Syzygy cycle at the time of
Perihelion. It is claimed that this reinforcement is part of a 31/62/93/186 year lunar tidal cycle
that produces variations on time scales of 9.3 and 93 years.
*******IMPORTANT PART******
Finally, an N=4 standing wave-like pattern in the MSLP that circumnavigates the Southern Hemisphere every 18.6 years will naturally produce large extended regions of abnormal atmospheric pressure passing over the semi-permanent South Pacific sub-tropical high roughly once every ~ 4.5 years. These moving regions of higher/lower than normal atmospheric pressure will increase/decrease the MSLP of this semi-permanent high pressure system, temporarily increasing/reducing the strength of the East-Pacific trade winds. This may led to conditions that preferentially favor the onset of La Nina/El Nino events.
Mike McMillan says:
Better version of the image:
http://cdn.physorg.com/newman/gfx/news/hires/2013/climateresea.jpg
Thanks, has anyone got a clearer version figure 2 with the power spectra of the observations. It looks like they are being a bit liberal with frequencies they are choosing to adopt . May help explain the frequency question.
I am sorry if I am just repeating what others have said but I think the author’s of this Nature Geo-Science paper are saying that 15 month winds are just the beat period between the ~ 5 year ENSO cycle and the annual seasonal cycle.
(5 x 1) / (5 – 1) = 5/4 years = 1.2500 years = 15 months
What they are probably seeing are winds which are following the beat period between the 4.65 year = (quarter of the 18.6 Draconic lunar tidal cycle) or 4.43 year ( = half of the 8.8502 year perigee pecession cycle), which are both ~ 4.5 years in length, with the annual seasonal cycle.
(4.5 x 1) / (4.5 – 1) = 4.5/ 3.5 years = 1.2857 years = 15.43 months
Bob Tisdale says: “.. and the seasonal cycle in the westerlies (during El Niños), which are a function of the warmest waters wandering seasonally between the hemispheres, and how ENSO alters the normal 12-month cycle so that it’s 10 to 15 months.”
Do you have a link to any data on this “wandering”? That would seem to be the key here.
Thx
Wandering either side…
When either side, trades are strong, when in the middle trades are weak, hence the wind intensity is half the true frequency of interference pattern which is (f-1)/2
People should stop using the “beats” frequency unless they are talking about a full wave rectified phenomenon and can say why.
It is not really the “frequency” since the amplitude signal is a folded (rectified) cosine. There is a repetition period but “the frequency” invites the incorrect idea that it is still a cosine.
It is not a folded (rectified) cosine if the parameter in question (e.g. trade wind speed strength) is oscillating about some long-term equilibrium value i..e we are speaking of the Trade Wind anomaly. The frequency is then just the time for the mean wind speed to return to its previous values.
I am assuming that Bob can show a correlation between the Trade Wind speed anomaly and the signed latitude of the location of the West-Pacific warm pool?
I’d think that major volumes of water with different heat contents sloshing around in the Pacific would affect wind patterns and not the other way ’round. We’ll see.
Yes, My gut feeling is that it’s ocean currents driving winds rather than the opposite. Tail shakes dog etc.
Greg Goodman says: “Do you have a link to any data on this “wandering”? That would seem to be the key here.”
All you have to do is plot and compare the sea surface temperatures (not anomalies) of the Northwest and Southwest tropical Pacific to see the opposing cycles in the temperatures. Here are the climatologies for both:
http://i41.tinypic.com/if2wki.jpg
Source:
http://nomad3.ncep.noaa.gov/cgi-bin/pdisp_sst.sh?ctlfile=monoiv2.ctl&varlist=on&new_window=on&lite=&ptype=ts&dir=
Regards