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
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re 18.6 : I don’t know if you want to call it a tide but there is a periodic effect that will displace water volume. As the angle of declination is reduced, the obliquity of the liquid earth will increase. As declination increases the force will be less centred on the equator, obliquity will reduce. This implies a movement of mass. I think you already pointed out this is visible in LOD.
The other effect that I’m trying to quantify, since I suspect it is more important, is the effect of precession of the line of periapsis.
The perigee migrates from one hemisphere to the other and back with a period of 8.85 years. As I demonstrated, this period is abundantly present in many climatological time series and multiple peaks in the Stueker paper can be traced back to this periodicity.
I’m trying to understand why but I’m having a lot of difficulty in finding information on the latitudinal variation in the position of lunar perigee. Everyone seems focused simply on the magnitude.
The average eccentricity of lunar orbit is about 5%. Since tidal force is reckoned to vary with inverse cube that makes 15% . Now it seems to me that a variation of 15% in the prime driver of oceanic tides that is continually asymmetrically offset into one hemisphere for 4.43 years at a time could displace significant amounts of water.
My spectral analysis of wpac850 trade wind speed finds an AM triplet centred on this period.
http://climategrog.wordpress.com/?attachment_id=281
3.475 4.431 5.424
Stuecker et al found almost exactly the same figure for the first: 3.745 cf 3.759 but did not find the other two as I did. Their PC1 and PC2 EOFs showed 4.854 4.90 years.
now the mean _frequency_ of 4.431 5.424 = 4.877 years
Stuecker et al 2013 simple failed to resolve the two peaks. Had they done so they would have found as I did that there is a perfect amplitude modulation triple based on 4.43 years : the frequency with which the perigee cycle affects the equatorial region.
The effect is clear and is clearly attributable to this cycle. It remains to understand the mechanism. That is why I’m trying to asses the volume of water that could be displaced by asymmetrical displacement of this 15% variation in the lunar tidal force.
Paul Vaughan says: http://img268.imageshack.us/img268/8272/sjev911.png
That’s interesting. The period in which they are out of phase is the one that Keeling identified as being dominated by 6 year rather than circa 10y periodicity (10 is probably just confounding 9 and 11). He also points out that 6.0 years is 8.85 combined with 18.6 .
The analysis being discussed here shows the lunar signal is still very present in the recent climate, it was apparently a more significant proportion of the whole during the earlier period.
“Stuecker et al 2013 simple failed to resolve the two peaks. Had they done so they would have found as I did that there is a perfect amplitude modulation triple based on 4.43 years : the frequency with which the perigee cycle affects the equatorial region.”
Re-reading that it could sound like unfair criticism. It should be noted that it is possible that their processing failed to resolve the peaks because they are blurred in the physical wind speed data they chose to analyse which was not identical the wpac850 dataset I used or because it was lost in ERA40 “reanalysis” modelling. Another reason to prefer to do such work on real data rather than reanalysis model output.
Greg Goodman (June 3, 2013 at 1:28 am) wrote:
“The period in which they are out of phase is the one that Keeling identified as being dominated by 6 year rather than circa 10y periodicity (10 is probably just confounding 9 and 11). He also points out that 6.0 years is 8.85 combined with 18.6 .”
The 6 year tide isn’t news. On the contrary, it’s well-known.
Actually, the beginning of the cycling 9-11 phase contrast coincides with the middle of Keeling & Whorf’s suggested 6 year dominance window. Keeling & Whorf saw enough to laudably raise an important issue (rather than ignore it as had become mainstream convention), but crucial insights arose in later literature. Be careful here to recognize hierarchical confounding.
This is the crucial piece of the puzzle you’re missing:
Mursula, K.; & Zieger, B. (2001). Long-term north-south asymmetry in solar wind speed inferred from geomagnetic activity: A new type of century-scale solar oscillation? Geophysical Research Letters 28(1), 95-98.
http://spaceweb.oulu.fi/~kalevi/publications/MursulaAndZieger2001.pdf
That signal shows up as the most interesting & most crucially informative centennial-scale feature of multivariate geophysical records of the past 150 years. The asymmetry of the heliosphere flipped over and the synchronized impact lights up in terrestrial annual persistence summaries like a flashing multivariate Christmas tree. If you need a review of related links, you’re welcome to ask. (This isn’t something you can safely ignore.)
Greg, I’ve decided this needs to be said frankly:
If you stubbornly insist on sticking only to temporally-global summaries, you’re guaranteed to remain ignorantly blind to crucial solar-terrestrial insights that flow easily & effortlessly from adjustably-windowed summaries.
For far too long die-hard old-school temporally-global analysis agents of ignorance &/or deception have been allowed a free pass on diagnostic integrity. The climate discussion has been darkened and set back by years if not decades by this fatally persisting conceptual log-jam.
Sensible analysis cannot be based on patently false assumptions (e.g. cycle length stationarity). If it has not already expired, my willingness to continue turning a collegial blind eye on this particularly egregious issue has worn paper thin.
Using hammers to sink nails is sensible. Hammers are useful, but a hammer isn’t the right tool for sinking a screw.
“If you stubbornly insist on sticking only to temporally-global summaries …..Sensible analysis cannot be based on patently false assumptions (e.g. cycle length stationarity). If it has not already expired, my willingness to continue turning a collegial blind eye on this particularly egregious issue has worn paper thin.”
Paul , I asked you to discus that issue about 10 days ago and you said ‘when the time and place is right’. Perhaps you now feel it is.
Wavelet analysis gives an interesting perception of the data. But like all kinds of analysis it is not the one imputable truth and like all analysis it needs skillful interpretation.
When I posted my article on Talkshop your last comment was this:
“So the power’s not always there, but you can make it look like it is.
That doesn’t mean the signals aren’t informative. Intermittent signals of common period observed in multiple basins: That’s interesting and it shouldn’t be ignored.”
The counter argument is even if a signal is there all the time , with limited window wavelet processing you can make it look like it isn’t/
Consider something like you two 9 and 11 years signals plus a 6a and a bit noise. If you chose a period like 1940 to 1955 when the two are out of phase , when you pass, say a 15 year wavelet, it will tell you about the noise and six year and probable miss the 9 and 11a because they are mutually cancelling each other and not clearly expressed in that part of the data. It will probably also somewhat misdiagnose the 6 year and other signals by confounding what is really the residual of 9 and 11.
A full length Fourier analysis would correctly reflect this.
There are other situations where wavelet may give alternative insights into the data, the art is in the interpretation of what various techniques reveal , not thumping on the table and name calling.
You seem to be of the impression that wavelet trumps full width spectral approach and call anyone using later ignorant or worse.
Now if a signal is of celestial origin, like the lunar cycles I am finding. I know it is not of variable period , neither is it only going to be present from 1925 to 1945 or whatever. If it’s there, it is there. It may be modulated by something else, or cancelled by interference but it is always there.
That is my reason for preferring that particular tool which is well adapted to detecting what I am trying to identify.
I would also say that if a periodic signal has a variable period it is not periodic. It is either a non-periodic variable that someone is trying to shoehorn into being periodic or a mixture of different periodic variables that have not been fully resolved.
Your 9 & 11 plot seems to be a case in point. Both those cycles seem to be modulated by at least one other. A character called Bart made a very insightful analysis of SSN that was reproduced on TS some time ago. He resolved the whole thing down to an interplay of two fundamental , purely harmonic functions (of constant period ! ) .
I think you need to mitigate the apparent importance you accord to wavelet techniques, which you seem to regard as the ultimate in frequency analysis.
Sensible analysis cannot be based on rejecting patently obvious conditions like stationarity of lunar cycles.
It seems I was misunderstanding perigee variation somewhat but in essence is still there. Perhaps AGF could confirm or correct as appropriate.
perigee is always in SH and only varies in latitude with declination angle over 18.6 years. However magnitude varies and hence inv. cube varies. on a 8.85 year cycle.
This gives a modulation that Keeling correctly drew attention to. This gives both 6.0 and 16.88 as the equivalent linearly superposed components that will be found in a spectral analysis.
Paul Vaughan says:
June 2, 2013 at 8:25 pm
General comment (to everyone) to correct a tired old (often seemingly deliberate) misrepresentation: LOD is not suggested as a climate driver. It’s a climate indicator with exceptional diagnostic utility since it’s so well-constrained in aggregate by the laws of conservation of angular momentum & large numbers.
==================================================================
But one of our bright lights, Nils Axel-Morner, has clearly invoked LOD directly as a climate driver:
http://wattsupwiththat.com/2011/07/05/nils-axel-morner-arctic-environment-by-the-middle-of-this-century/
And another contributer claimed tides interfered with sea currents to drive ENSO:
http://wattsupwiththat.com/2013/01/20/analysis-shows-tidal-forcing-is-as-a-major-factor-in-enso-forcing/
So it took me a while to figure out that GG and others were not invoking physical interference of the tides but rather their heat carrying capacity. This concept was new to me and seemed highly unlikely in practice, but as noted above, I have come to accept it in principle. –AGF
AGF, thanks. It always more use convincing someone who thinks you completely wrong. Especially since you seem to have a good understanding of tides.
Are you able to help with _farthest_ perigee value? Everyone seems excited about nearest perigee but I can only find farthest values for each year.
Here’s a list of the ten nearest and ten furthest perigees simulated over 6ky:
http://en.wikipedia.org/wiki/Talk:Orbit_of_the_Moon
Thanks. That’s a start. If I take the max/min perigee as percentage and x3 for the cube it gives 12.3% change in tidal forcing a the extreme variation.
I’m a little concerned nearly all those values are pre 1000 AD. Don’t know whether exentricity is declining or model is not accurate that far back. I’d prefer to work on values for last 200 years only, but it’s a first approx.
thanks.
Greg, wavelets are more flexible than most realize — temporally-global analysis is just a special case. At the Talkshop I suggested that you extend your methods to a network approach — e.g. like Tsonis+. In an infinite network of coupled oscillators paradigm, nonstationarity gives a huge family — or a “raised noise floor” as some would say. Some classes of wavelets let you skip that dead end by cutting directly to the amplitude modulation. That’s how I did the volatility weave work. It’s easy. Use a hammer, a screwdriver, or a screwdriver that can effortlessly transform into a hammer, like the class of multi-grain, multi-extent, multi-span wavelets I use ….or use whatever. Using lots of methods is best. Let’s just all share and see where it goes. We all have different backgrounds. Yes, careful interpretation is the key — we agree effortlessly on this. Again: I appreciate your contributions. There’s plenty more potential for productive sharing ….but like always I’m just short on time. Moving forward we need to find a way to communicate more efficiently. Maybe if you start exploring your interference patterns using large scale circulation to guide aggregation in a Tsonis-like network, you’ll make a spatiotemporal pattern breakthrough. I don’t have the time and the computing resources to do what I have in mind, but maybe you do …
AGF, glad to see you’re open minded about what Jean Dickey is teaching us — i.e. that mass, temperature, & velocity are coupled — e.g. when mass moves, it can take heat with it. I think we could all be more efficient with our collective explorations if we could find a way to skip sidetracking misunderstandings – (may be a more difficult problem to solve than climate, but also an interesting component of nature).
It’s the sun that maintains & shifts temperature gradients, which drive large scale circulation. That’s what I find beautiful. There’s plenty more to illustrate more carefully as time permits.
I’m feeling pressed for time, so I’m leaving it at that for now…
All the best…
The final version of our paper has now been published:
http://www.benthamscience.com/open/toascj/articles/V007/TOASCJ130415001.pdf
Long-Term Lunar Atmospheric Tides in the Southern Hemisphere
Ian R. G. Wilson and Nikolay S. Sidorenkov
The Open Atmospheric Science Journal, 2013, 7, 51-76
” e.g. like Tsonis+. In an infinite network of coupled oscillators paradigm,”
Yes, I think that is ultimately to only was to arrive at a realistic model. However, a first step it to identify the prime movers. You can’t just wave around some impressive term like “infinite network of coupled oscillators” plug it into OLS and get a model. You need to have damned good idea of what the major patterns are before you try to model them.
There are three stages in scientific investigation: observation, analysis, hypothesis.
The reality of climate science has a fair but inadequate amount of the first and is in the rudimentary stages of the second. Unfortunately, there is a large body of mainstream climatology trying to pretend they are close to finishing the third step and can now project climate 100 years hence based on poor quality hind-casts of the last 50.
“nonstationarity gives a huge family — or a “raised noise floor” as some would say.”
So can non linearity, and in poorly resolved data the “noise” elements can shift the major peaks a bit to one side. That is why it is important to chose the right variable to analyse (eg wind speed or square of wind speed) and to take measures such taking time differential of data like temperature that are strongly autoregressive and parameters such as wind speed that are heavily dependant on them.
Professor Timmerman has some impressive talent down there in Hawaii, and other aspects of this study seem very rigorous, that leaves me rather confused as to why they got the basics of the signal processing so wrong and failed to continue the amplitude modulation interpretation to reveal the strong lunar influence. Maybe they did but it is not currently ‘politically correct’ or financially astute to report it. Apparently Keeling felt it necessary to couch it all in conditionals as far back 1993.
To be honest I think they simply missed what was right in front of them.
@ur momisugly Greg Goodman
clarification: Tsonis+ network approach = exploration (not modeling)
Moving forward I propose we limit exchanges to ruthlessly condensed notes.
___
from google search for:
“4.5 year” climate
http://oceanrep.geomar.de/16413/1/2012_Dengler_etal_THOR_NA_Climate_Cycle_and_Heat_budget.pdf
http://amma-conf2012.ipsl.fr/data/documents/PL7_1_Brandt.pdf
http://www.clivar.org/sites/default/files/imported/organization/atlantic/meetings/tropical_bias/talks/Brandt.pdf
http://tallbloke.wordpress.com/2012/10/09/is-this-the-4-5-year-cycle-in-argo-and-tropical-atlantic/
beat of semi-annual with QBO nearest harmonic ~= 9 years ~= half-Saros ~= Saturn-Earth-Venus ~= solar North-South asymmetry ~= 2 * Neptune-Earth-Venus ~= 2 * ENSO LF ~= beat of semi-annual with ENSO QB nearest harmonic
__
@ur momisugly Ian Wilson
thanks for update — appreciated
Wilson & Sidorenkov (2013). Long-term lunar atmospheric tides in the southern hemisphere.
http://www.benthamscience.com/open/toascj/articles/V007/TOASCJ130415001.pdf
__
Loose end to be addressed elsewhere in future:
direct illustration of solar asymmetry 9 year phase shifts and connection with NPI and July & August ENSO (should already be obvious to careful observers)
__
Crucial Reminder:
http://imageshack.us/a/img267/8476/rrankcmz.png
Paul Vaughan says:
June 3, 2013 at 7:52 pm
============================================================
Here’s what else Jean Dickey is trying to teach us–the earth’s core drives the climate–the rest is anthropogenic:
http://journals.ametsoc.org/doi/abs/10.1175/2010JCLI3500.1
–hardly an improvement over Axel-Morner’s LOD driver.
The statisticians are always in danger of falling into holes of gematria and numerology and otherwise missing the big picture. After all, the pre-Copernicans weren’t too bad at predicting eclipses. –AGF
thanks Paul , out of time I’ll dig that lot later.
Brandt looks interesting, I’ve already suggested that ENSO is lunar and global El Nino impacts are probably common cause not teleconnection.
I suspect that will confirm my lunar perigee hypo is also found in Atlantic.
Thx
climategrog (June 5, 2013 at 8:25 am) wrote:
“[…] I’ve already suggested that […] global El Nino impacts are probably common cause not teleconnection.”
I’ve been saying something equivalent for years, but I’ve expressed it quite differently (spatiotemporally balanced multi-axial circulatory-loop differential).
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@ur momisugly AGF
Jean Dickey’s background is physics, not stats.
http://scienceandtechnology.jpl.nasa.gov/people/j_dickey/
Dickey & Keppenne (1997) is a landmark paper. As you may recall, I’ve made some very harsh remarks about some of Jean Dickey’s later work.
___
May we have more efficient, more harmonious communications moving forward.
All the best.
Paul Vaughan:
“Moving forward I propose we limit exchanges to ruthlessly condensed notes.
beat of semi-annual with QBO nearest harmonic ~= 9 years ~= half-Saros ~= Saturn-Earth-Venus ~= solar North-South asymmetry ~= 2 * Neptune-Earth-Venus ~= 2 * ENSO LF ~= beat of semi-annual with ENSO QB nearest harmonic”
ruthlessly condensed: numerology.