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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Interesting. I’ll have to take a closer look.
“…interaction between El Niño and the seasonal evolution of temperatures in the western tropical Pacific warm pool.”
That sounds suspiciously like “interaction between El Niño and La Niña effects,” which we already know are concatenated.
If it’s a 15 month cycle, the question “Why does El Niño always peak around Christmas and end quickly by February to April?” remains unanswered. Christmas is a 12 month cycle. It’s models. I’m underwhelmed, unless they have more than is indicated here.
At least the modelers are attempting to describe natural patterns and, thereby, admitting that they exist in reality apart from their models. That is a far cry from the old model centered approach to everything. Their particular claims might be dead wrong but they are now looking toward reality and might engage in empirical research.
So what causes the unusual wind patterns that affect the El Niño? It appears to me the root cause for both phenomenon is still missing.
My first instinct is to say “yeah, maybe that is true … sometimes”. Maybe there is a 15 month cycle as conditions are currently set right now but there is evidence that during the last glacial we had long term persistent La Nina conditions. In other words, that 15 month cycle can change, or go away, if the conditions that cause it change.
Four 15 month cycles = 60 months = five 12 month cycles.
Is this trying to say one El Nino every five years?
$32 for the article.
Paywalled of course.
So how many cycles have they measured?
Or cause they saw it once,therefore its a recurring cycle?
Or is is modelled to oblivion?
My distrust of the climatology profession is such I would not spend $32 to find out more.
you know if they tied the 15 month cycle to the orbit of juniper and saturn and sun spots people would have no doubts about a paper they havent read.
Lovely juxtaposition of art with science… why not call El Nino’s anomalous “combination tone” a Modular or Tartini Effect, recalling Giuseppi Tartini (1692 – 1770) as Maestro di Cappella, founder of a famed school in Padua, patron of Stradivarius, who published numerous treatises on acoustics and harmony from 1750?
juniper? Works for me.
For Mosher:
The full moon cycle is slightly less than 14 synodic months and slightly less than 15 anomalistic months.
OMG- it’s teh moon!
Here is another bunch that still doesn’t understand atmospheric circulation…
“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.”
Sera says:
“The full moon cycle is slightly less than 14 synodic months ….”
Well, no, the Full Moon cycle is EXACTLY 14 synodic months, by definition.
.
Well, we knew it was something like that. Being from Hawaii, it has always been an issue. Since discovered. And that was not so long ago, I might add. After the currents were mapped, and Hawaii is in a peculiar situation with regards to that, we knew something was ruining our lives every 20 years. Good work. real science is so much more important than pretend science.
” …but they are now looking toward reality and might engage in empirical research… but they’e still reading map to ground, and the map still has,”Here there be Dragons” writ large upon it.
Uh…
I heard it was from a shift in the tradewinds in the 80s… Did we lose a book at some point?
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
This is not the origin. What causes the un usual wind pattern. That’s the problem with models, they don’t model the real world.
Interesting reference to Giuseppe Tartini, violinist, composer, and theorist as well as violin maker of the 18th century. Though he wrote many pieces, including over 150 violin concerti, his most popular work remains the violin sonata known as “The Devil’s Trill” from its difficult and acrobatic double stops. He did, indeed, discover both combination tones and difference tones, which he described and demonstrated in a major theoretical thesis circulated widely in both printed and manuscript copies during his lifetime, though not published in a reliable scholarly version until the 1950s and in a more modern translation in the 1990s. As a composer, I learned in college in the 1960s about both types of un-notated but audible tones, which are producible both on string instruments (but most easily on violin) and on certain wind instruments, especially the bassoon, through cross-fingerings. I found the information quite interesting, but was never able to apply it in my own compositions and have largely forgotten the specifics.
Now–how does the concept of combination tones (or difference tones, for that matter) apply to the weather? That linkage in the article was diaphanous in its vagueness, though I assume the authors have some specific idea of how the theory applies in natural settings in and over the Pacific Ocean.
Theo Goodwin says:
“At least the modelers are attempting to describe natural patterns and, thereby, admitting that they exist in reality apart from their models. That is a far cry from the old model centered approach to everything. Their particular claims might be dead wrong but they are now looking toward reality and might engage in empirical research.”
Yes, at least they are looking now. Their combination time is the same as harmonic interference, so they may actually be looking in the right direction.
A very interesting pattern came out of the recent discussion on volcanic forcing
I applied Willis’ stacking idea but kept calendar months aligned. A surprisingly regular pattern emerges:
http://climategrog.wordpress.com/?attachment_id=278
Now several papers have referred to Nina/Nino-like variations timed after eruptions.
What this plot shows is that most of the supposed volcanic cooling would have happened anyway and is part of a cycle that was present before and after the events.
Does this imply a synchronisation of El Nino pattern and timing of eruptions. That would imply common cause ….
I think this is more of a sequence than a cycle, since it doesn’t repeat after being triggered, so there isn’t any need for the 15 months to tie into anything. It just takes that long for the phases to time out. Then it waits for the combination of conditions that trigger it to show up again, which happens often enough, but not on any schedule.
Better version of the image:
http://cdn.physorg.com/newman/gfx/news/hires/2013/climateresea.jpg
I have been suggesting for a while that El Nino could be a slow, basin wide tide in the thermocline. This would behave in a similar way to surface tides but with the density difference being much smaller than air/water difference the time-scales would be proportionally longer.
To my mind this makes more sense the “water piling up because of winds ” explanation that seems to be the current orthodoxy. There may be an inertial cause for the bulk movement of water.
We’ll find out soon enough. I’m not holding my breath.
“Now–how does the concept of combination tones (or difference tones, for that matter) apply to the weather? That linkage in the article was diaphanous in its vagueness, though I assume the authors have some specific idea of how the theory applies in natural settings in and over the Pacific Ocean.”
http://en.wikipedia.org/wiki/Beat_%28acoustics%29
this also relates to amplitude modulation.
https://forum.arctic-sea-ice.net/index.php/topic,174.msg2880.html#msg2880
The author’s 1 year and 5 years will produce frequencies(1+1/5) and (1-1/5) per year, ie 1.2 and 0.8 per year.
That gives 15 and 10 months. Like many doing this kind of calculation they seems forget (or not realise) the second is just as important.
this kind of thing is trade stock for those looking planetary effects and is essential whatever the cause of climate oscillations if we are to understand interactions. Good to see this is not being examined.
If climatology did less econometrics and more engineering type analysis they may find some surprising things. 😉
An intersting example from variations in Arctic sea ice coverage
http://climategrog.wordpress.com/?attachment_id=216