Guest Post by Willis Eschenbach
On another thread, a poster got me thinking about the common practice of using the El Nino 3.4 Index to remove some of the variability from the historical global average surface temperature record. The theory, as I have heard it propounded, is that the temperature of the Earth is “signal”, whereas the El Nino cycles are natural swings and as such are just “noise”. So if you remove the El Nino swings from the temperature, the theory goes, then we can see more of the underlying temperature signal by removing the noise.
Figure 1. Various “Nino regions” used in the study of the El Nino / La Nina phenomenon. Each area has its own index, with one of the most commonly used being the Nino 3.4 Index. SOURCE. See also the NOAA page
The more I thought about the practice of subtracting the Nino 3.4 variations from the global average temperature anomalies, the more questions came up for me. I don’t have the answers, hence this post. The first question that came up is, how do we decide that the Nino 3.4 Index represents noise instead of signal?
The Nino 3.4 region covers about 2.4% of the planet’s surface, a bit bigger than the USA. So … why isn’t the temperature of the USA “noise”? Or perhaps, is the temperature of the US “noise” but no one ever checked? And how would you check? What mathematical procedure would allow us to discriminate? What test would we use to say well, Nino 3.4 is noise so we can safely subtract its effects from the global temperature signal, but, for example Nino 1+2 is not noise, it’s part of the signal?
My next question about the situation revolves around the fact that the Nino 3.4 Index is merely a linear transform of the sea surface temperature of the Nino 3.4 area. So what we are doing is taking a linear transformation of the surface temperature anomaly in one part of the world, and subtracting it from the global average surface temperature anomaly.
As a result the question is, is this a legitimate operation? Subtracting a linear transform of something from the whole of which it is a part? Like, say, taking the average temperature variations in the whole US including Texas, but then subtracting out some linear transform of the temperature variation in Texas? What is the meaning of that procedure, subtracting something from itself? And if we are going to subtract a transform of say the Nino 3.4 temperature from the global average, should we include the Nino 3.4 temperature to begin with when we calculate the global average, or not?
Next question is, is this a legitimate operation in a system with a thermostat? Like for example, taking the variations in my body temperature, but subtracting out some linear transform of the temperature variations in my foot? What does that procedure give us, what does the result mean?
Next question. If we’re going to remove the transform of the El Nino Index from the global average temperature record, then should we remove the other indices as well? Should we remove the AMO (Atlantic Multidecadal Oscillation) Index? The PDO (Pacific Decadal Oscillation) Index? The Madden-Julian Oscillation Index? Some combination of them? All of them?
Final question. From my perspective, the El Nino/La Nina oscillation actively regulates heat loss, and thus is part of the planetary temperature regulation system. It regulates the heat loss by way of both the ocean and the atmosphere. Let me give a functional explanation of how it works. The explanation is slightly but not significantly simplified.
During La Nina conditions, in the upper part of Figure 2 below, the warm blanket of water normally covering the Pacific has been blown to the west by the strong eastern trade winds. From there, that mass of warm Pacific surface water splits and moves north and south along the coasts of Asia and Australia towards the Poles. The mass of water is radiating and losing heat as it travels. Functionally, the El Nino/La Nina alteration serves as a huge, slow-cycling, thermally regulated Pacific-wide pump. The La Nina pump stroke moves warm Pacific surface water poleward to lose its heat through conduction, radiation, and evaporation.
Figure 2. La Nina and El Nino conditions. North and South America are the brown areas in the upper right. Australia is at the lower left. Black arrows in the atmosphere show the direction of atmospheric circulation. White arrows show surface ocean currents SOURCE: NOAA El Nino Theme Page
In addition to moving warm Pacific water poleward, the removal of the warm Pacific tropical surface waters exposes the atmosphere to huge amounts of cooler sub-surface Pacific water. This lowers the air temperature over that whole area of the tropical Pacific. Soon, however, the surface of the Pacific starts to warm again. One effect of this is that it slows down the eastern trade winds. As a result of reduced winds and reduced clouds, the warming of the surface of the Pacific continues. In addition, some of the warm surface water in the Western Pacific moves back out east. Soon, with the sun beating down on an ocean with reduced clouds, it warms up all across the Eastern Pacific. This leads to neutral conditions, which can last a while.
However, if the tropical Pacific surface temperature warms enough, then El Nino conditions develop. After the El Nino conditions come into being, at some point as the surface of the Pacific continues to warm, and the El Nino thunderstorms drive the surface air upwards, the eastern trade winds start to strengthen. Soon the eastern trade winds start pushing the warm tropical surface waters and their associated thunderstorms and clouds to the west across the Pacific and eventually poleward again. This is the power stroke of the pump, when the trade winds strip the warm surface waters off and push them westwards. In this process, the full La Nina conditions come into existence. Finally, the La Nina conditions eventually peter out to a neutral condition once again.
Note that this system is triggered by temperature. If the temperature doesn’t build up across the surface of the eastern Pacific for some reason, then things stay neutral, neither El Nino or La Nina. In that case, the El Nino doesn’t form, and so the eastern trade winds don’t build up to pump the warm water across the Pacific and towards the poles.
But when the surface waters of the Pacific do heat up beyond a certain point, El Nino conditions arise, the eastern trade winds strengthen and pump the warm tropical surface water, first across the Pacific and then to the poles. It also exposes the atmosphere to a large area of cooler subsurface water.
Note the effect of this amazing temperature regulating heat pump. It functions to prevent any long-term buildup of heat in the waters of the surface Pacific. If the water in the surface of the Pacific stays cooler, the heat pump doesn’t kick in. But as soon as a certain amount of heat builds up in the surface Pacific waters, the El Nino/La Nina alteration occurs, pumping the surface water west to be flushed out toward the poles. The layer of warm surface water that was blown west is then replaced by cooler water from the subsurface, cooling the entire tropical Pacific.
This mechanism, this El Nino/La Nina pump skimming off the hot Pacific water and pumping it to the poles, prevents long-term Pacific heat buildup and thus actively keeps the planet from both overheating and excessive cooling. It is one of the many interacting thermoregulating mechanisms that keep the earth from either overheating or becoming too cool.
So … this brings up the final question regarding the theme of this post.
Since the variations in the Nino 3.4 index are indicative of the functioning of one of the Earth’s major thermoregulating mechanisms, namely the giant El Nino/La Nina pump that magically materializes to move warm tropical Pacific water to the poles whenever the planet gets too hot and sweaty … then under what possible construction could the Nino 3.4 Index variations be called “noise”?
Like I said … lots of questions, I don’t have the answers, all courteous contributions welcomed.
Regards to all,
w.
The reason why ENSO signals are taken out from the global TEMPERATURE graphs is because 1 cubic metre of water holds about 4000 times as much ENERGY as 1 cubic metre of air.
As noted in several posts above, ENSO events transfer heat between the atmosphere and the ocean. So if the ocean takes up lots of energy, the TEMPERATURE rise will be smaller than if that energy were distributed amongst the atmosphere.
If a graph were produced of global thermal ENERGY, and the measurements were fine scale enough to capture the temperature distribution within the ocean due to events such as ENSO, then any AGW signal (or lack of it) should become evident.
Several climate scientists note that 90% of AGW warming is going into the oceans. In reality, we can almost neglect what is happening in the atmosphere, and just look at the temperature of the ocean.
Matthew W says:
January 17, 2013 at 10:22 am
No, sorry for the lack of clarity. I am saying that a linear transform of the subset is being subtracted from the total 100% set. This is generally done in the usual way, via linear regression.
w.
Bill Illis says:
January 17, 2013 at 10:23 am
Bill, if you do a linear regression with enough variables you can simulate anything.
But wait, it’s worse. When you do what you do, which is to include among your explanatory variables things like the Nino 3.4 Index, which is a subset of what you are attempting to predict, or optical depth (AOD), which is in part a function of temperature, then all bets are off. Of course you can hindcast HadCRUT if you do that, that’s a no-brainer. See Enrico Fermi’s story of Johnny von Neumann and the elephant.
Of course, such a system is totally useless for forecasting temperatures.
You should also repeat your regression, using solely the first half of your data, and see how well the regressions parameters are able to hindcast the other half of the data.
Then repeat the procedure using just the second half of the data to establish your regression parameters, and see how well those parameters are able to hindcast the first half of the data …
I suspect the results might surprise you … but in any case, you can’t use temperature data to hindcast temperature data, that’s cheating. Think about the AMO Index. You want to use that to simulate the temperature, but the AMO Index is nothing but a mathematical transformation of the temperature in the North Atlantic … which is part of what you are trying to simulate. You can’t use the temperature to simulate the temperature, you’ll be successful every time.
So you are correct, your result is no fluke. Instead, that kind of reconstruction is the inevitable result of 1) lots of variables and 2) some of the variables being part of what you are trying to simulate.
w.
rgbatduke says:
January 17, 2013 at 9:29 am
My only comment on this description of the heat pump is this. The planet cools more efficiently when the heat absorbed in the tropics is not transported towards the poles. Because the heat is ultimately lost via T^4 radiation, anything that reduces temperature variation on the surface area by transporting hot spot heat elsewhere has a net warming influence.
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First I second everything you say about a need to directly attack global squalor rather than taking to the pulpit to make blanket condemnations of one’s fellow man and conjuring Doom by greenhouse effect. I’m not sure I follow the argument on how a hotspot not moving poleward nets out as cooling. It seems a hotspot would radiate in the same way regardless of where it was. Do you think that hotspots cool by mixing or is it primarily just radiative? The bone I am picking at is that heat moving elsewhere toward the pole does not improve on the earth’s cooling in and of itself. I think of the earth as cooling the same all the time (absent the effect we’re discussing and water vapor effects.) It’s kind of a circular aspect of the argument; given a hotspot it’s going to end up cooling more effectively no matter where it is, but if it persists longer then it’s true that it’s going to be even more effective. I do agree with the general proposition you present – that the more uniform the temperature of the earth the lower the rate of cooling. This all comes up when thinking about whether a fast spinning planet cools differently than a slow one (like the moon). My answer has always been that it has to do with properties of rock on the surface. If things were such that rocks barely had time to cool before the sun rose again, it wouldn’t make much difference, but if rocks quickly cool down, then yes the average temperature would be cooler because then the planet (or moon) would be less uniform temperature-wise. All this rumination, of course, underlines what you have said, that it’s not a simple model. My suspicion is that the net greenhouse effect of doubled CO2 is probably about as negligible as the effect of all humankind’s impoundment of water on the climate. There is a theoretical effect and a doubling sounds substantial but that doubling is in the context of a much larger and wildly varying greenhouse effect from water vapor.
Roberto says:
January 17, 2013 at 12:21 pm
If you think that strictly linear model has any chance of even vaguely resembling the climate, you don’t understand the climate. It is a wildly non-linear system. Sadly, that linear assumption is the dominant climate paradigm.
In any case, the problem you are not grasping is that F1, factor 1, the Nino 3.4 index is not an independent variable. It is a linear transform of tropical Pacific surface temperature, something of the form:
F1 = a * Tp + b * time + c
where Tp is the temperature of that area of the Pacific.
So you are in essence subtracting something from itself … that’s what my question was about.
w.
Willis, you are right of course. The reconstruction is using part of the temperature record (although the ENSO part is three months prior).
But what is it that we are trying to do here?
Remove the noise and see an underlying temperature trend. A big part of the noise can be explained by these variables (even though some are not independent variables). The question was can we remove some of the variability. Yes.
Now forecasting is an issue. I can usually get the ENSO pretty close for at least 3 months out, which means 6 months out (considering the lag).
The AMO seems to be correlated with the ENSO (lagged several months) and with OHC in the north Atlantic going back to 1900 (lagged about 1 year) and OHC in the north Atlantic is going down now.
We can more-or-less tell what the solar cycle TSI is going to do for the next 4 or 5 years, and that is decline from its current +0.33 W/m2 to about -0.4 W/m2 although there really is not much of a solar cycle signal in the residuals.
CO2 is growing at a certain rate which is not difficult to extrapolate. The default is no volcanoes.
So, one can forecast ahead with this. The regression coefficients don’t change through time once you have a few decades of data. The ENSO impact is always the same (except for a multi-year event which looks to be higher), The AMO coefficient is 0.5.
Going farther out, one would assume the ENSO will balance out to Zero as it has since 1871. The AMO might follow its 60 year cycle (maybe not) and balance out to Zero over time.
So, the underlying trend of temperatures is there within +/- 0.2C white noise variation per month.
Noise and Noises are just signals that we do not understand.
rgbatduke- exactly I feel there is an element of racism involved also,in the lack of equality in Development. Greenies fear healthy, happy, prosperous , dark skinned people.
(Their son or daughter might marry one..) . I’m all three races,BTW…
I think it not just Green’s, but more like the collusion that used to exist between moonshiners and the church in NC. The church formally opposed drinking, because alcohol was clearly the tool of the devil. For years, it successfully prevented liquor by the drink, created blue laws restricting the sale of alcohol, kept many counties in NC altogether dry. This fit the interests of the moonshiners just fine, as the people of NC were going to drink regardless of what the church claimed from its pulpits (including a lot of the very church goers that by day would piously oppose drinking). A dry county was a godsend for the ‘shiners — huge demand, no other source of supply. Nobody voted more fervently against the freedom to buy commercial liquor than a moonshiner, not even a Baptist preacher.
We see exactly the same unlikely bedfellows in the Green movement. Show me a Green that actually gives up cars, washing machines, electric lights, computers, heated houses, and commercial goods made far away and transported at enormous expense in energy to the stores where they purchased them and I’ll show you a Green that has no voice because they have successfully marginalized themselves to where they cannot even publicly argue for their public stance. Al Gore is just like a Baptist minister who is all hellfire and damnation when it comes to public drinking but who gets regular deliveries from his local moonshiner just the same. The Gores are verbally consistent but behaviorally inconsistent (and wish to control your behavior far more than their own) just like the preacher man.
The real puzzles are the moonshiners. At first glance they look like the ones that should most favor legalization of booze, until you realize just how much they profit from its restriction in a world where opposition to drinking is a lot more posturing and lip service to a mythological ideal than it is any sort of actual universal sentiment. In our modern world, the “moonshiners” that are in bed with the Greens are the very energy companies the publicly defend. After all, nobody will ever vote to cut back their energy usage if it involves lowering their standard of living!
Seriously. Nobody. Ever. If they were going to vote for that they could start by “voting” with their own behavior, by turning their lifestyle back to the 19th century — no electric lights, no electric heat, horses for transportation, hand washing of clothes in cold water carried by hand from a well or stream, growing their own food, refusing to purchase manufactured goods. The Amish manage lives something very much like this, but I don’t see people running en masse to join the Amish.
They are perfectly happy, of course, to lower somebody else’s standard of living. Gore is rich enough that he doesn’t care what the price of gasoline is — he can still afford to drive his SUV and live in an enormous, heated house and fly all over the world and wear expensive, clean clothes and pretty much not be affected, just like the Baptist who is happy to vote against commercial liquor because he’s got his personal moonshiner regardless.
Energy companies, then, love it when Green’s argue for restrictions that raise the cost of energy. The demand for energy is nearly completely inelastic, their profit margins are more or less fixed, so higher energy costs simply apply their margin to an increased revenue base without them having to actually do anything more to earn the money! Hell, we’ve even turned otherwise honest farmers into moonshiners by legally mandating the burning of moonshine in our cars.
The Greens and Energy companies thus work in perfect accord. The more expensive wind power is, the more certain the coal companies are of continued coal profits. Only an alternative energy source that is actually cheaper than coal is to be feared.
Is there racism, conscious or unconscious, in this unspoken agreement? Probably. By chance or design, the 1/3 of the world that is the poorest are mostly of darker skin, mostly live in countries that were long exploited by imperialist European nations, and that became — and to a large extent still are — a source for cheap labor and raw materials that disproportionately profit people half a world away. Freedom, civilization and law are the enemies of the church and the moonshiner alike. A corrupt government where the sheriff’s cousin and preacher’s uncle is also the county moonshiner works far better than ABC stores and uniform laws and taxation with no personal advantage that gives the lie to the church’s cries of sin and damnation simply by “working”.
rgb
While I’ve never seen this properly articulated, I can answer your first question, which is really about what is signal and what is noise?
The theory is that net forcings drive atmospheric temperatures (ignoring diurnal and seasonal variations). Absent natural variability, atmospheric temperatures would be a direct function of net forcings with minimum lag.
The signal is the direct and (almost) immediate effect of net forcings. Everything else that affects atmospheric temperatures is noise.
Removing ENSO variability is an attempt to remove what is believed to be a major source of natural variability and so get a clearer picture of the forcings signal.
Don’t get lost in the trees. Temperatures (and energy) are physical. If you want to know the temprature of the US minus Texas, just subract the Texas data from the total dataset.
If there were 40 thermometers equally distributed around the globe, then one thermometer must represent the 2.5 percent of global surface in the eastern Pacific. Just subtract the data from that one thermometer.
bw says:
January 17, 2013 at 2:30 pm
Don’t get lost in the trees. Temperatures (and energy) are physical…..
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You missed the whole point. My temperature in mid NC mirrors the temperature of the Atlantic ocean so you can’t just subtract the data points for the Atlantic and remove it’s influence.
The 1930’s Dust Bowl is a classic example. A dust storm arrived in Washington [D.C.] all the way from the Great Plains. As a dusty gloom spread over the nation’s capital and blotted out the sun, Bennett explained, “This, gentlemen, is what I have been talking about.”
Eschenbach’s statement “The Nino 3.4 region covers about 2.4% of the planet’s surface”
implies a geographically defined subset of the earth’s surface. My solution follows in that context and excludes all other parameters. If you want to define the ENSO “signal” globally in the time domain, then I suggest you just average 30 periods of ENSO signal and subract that. The deconvolution of “signals” from “noise” in the time domain has consumed a large proportion of human endevour. I’d say that the net global ENSO “signal” is zero, thats the null hypothesis.
I see no point in contriving an “index” from the base data and subracting that. It’s like saying what is the effect of subracting the “Dow Jones Industrial Average” from the average stock market. It has no physical meaning. There are large numbers of people who try to detect information from stock charts. That’s a total waste of effort.
If you can’t measure something, then you can’t quantifiy it. Does the ENSO index have a distinctly physical meaning? Can other observers measure it and find the same value?
No one wastes time asking a tibetan guru what effect ENSO has on the global average temperature. If you want to spend your time usefully, then learn more about basic scientific methodology, eg. get a copy of “Introduction to Scientific Research, by E. Bright Wilson, Jr. and read if a couple times.
Phil says: “Several climate scientists note that 90% of AGW warming is going into the oceans. In reality, we can almost neglect what is happening in the atmosphere, and just look at the temperature of the ocean.”
There is nothing in the ocean heat content data since 1955 or in the satellite-era sea surface temperature data to indicate that AGW had any influence on the warming of the oceans. None whatsoever:
Did the 1997-98 Super El Nino affect global temperatures? This is what it looked like on December 19, 1997 .
http://www.ospo.noaa.gov/data/sst/anomaly/1997/anomnight.12.19.1997.gif
Daily UAH temperatures reached +0.843C on April 6, 1998. In December this year, 2012, UAH averaged only +0.202C or 0.641C less than it was on April 6, 1998.
Did the 1997-98 El Nino impact global temperatures? – only by as much as 0.6C.
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My favorite is the biggest Super-El Nino of all time in 1877-78 which got to about +3.4C in the Nino 3.4 Index.
Hadcrut4 temperatures spiked to +0.395C in February 1878 while the background temperature of the time was just -0.300C.
Did the Super-El Nino of 1877-78 affect global temperatures? – only by as much as 0.7C.
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The biggest La Nina of all time was December of 1988 at about -2.4C.
UAH reached a low of -0.309C in March 1989 and Hadcrut4 hit a low of 0.02C in Jan 1989.
Did the Biggest-although-not-Super-La-Nina of 1988 affect global temperatures? – well yeah.
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It is clear that the ENSO impacts global temperatures. There is long-winded explanation of how this happens but suffice it to say, there is a physical energy balance explanations for how it happens.
Now the temperature trend in Nino 3.4 is Zero since we have had good reconstructions of its index. It might be the only place on the planet which has Zero trend over the last 140 years. In part, because it has been well-measured by ships, has a long history of relationship to the SOI which has been carefully measured for more than 150 years, has a long relationship with fish catches and ocean temperaturee off of Peru, has a long relationship with its impact on global temperatures, etc. etc.
In short, the climate scientists didn’t think they could get away with adjusting its record up like everywhere else on the planet.
It is the most important region on the planet in terms of weather/climate.
ENSO looks like a unit root to me. The pulse changes temperatures permanently up or down. It is not a temporary effect. As a result OLS analysis of temperature gives a misleading result.
http://en.wikipedia.org/wiki/File:Unit_root_hypothesis_diagram.svg
Isn’t this what Bob Tisdale has been arguing? That ENSO is a step function, not an oscillation around a mean.
Well, Meteorology and Climatology I do not understand almost nothing but bringing my comfort zone, Mechanics of Turbulence, you can make an analogy.
When studying turbulent flows by numerical methods, it is possible to separate the large vortex swirls small. This is done because large structures dominate the overall flow, and is responsible for most of the energy. But small structures are critical phenomena for power dissipation.
This way filter filtering the signal and simply remove it from the study generally, we are missing mechanisms (energy dissipation, for example) that prevents the explanation of the behavior of the larger whole.
When the buffer enable (eg outside the boundary layer), and it is possible to consider the behavior of small vortices as homogeneous and isotropic. In this case, it overrides the global analysis of sub-grid functions that represent the characteristics of these small dissipative structures.
Let it be clear, it is not necessary to use in calculating the overall development of small spatial-temporal structures, however, from the point of view of its action median overall effect should be considered.
What is the correlation with the post? We have two errors in the filtering of local, first filtering is unduly expanded to a domain of amplitudes that exceed the conditions of homogeneity and isotropy, we are losing signal and resolution capability of the model. Secondly, small perturbations filter without substituílas also known by other function over time lose resolution in large structures.
In short, if you filter a local action (do not use the term cold signal) without boring the above conditions, the model fully committed.
bw says:
January 17, 2013 at 4:54 pm
The El Nino / La Nina phenomena are not cyclic, that is, they have no fixed periods. Because of that, it’s not possible to “just average 30 periods of ENSO signal”.
Well, there’s a variety of indices, one for each of the El Nino areas … each one has a defined meaning, which other observers can calculate independently and agree on.
I haven’t a clue who this is aimed at. If it’s aimed at me, you haven’t shown that I need an introduction to scientific research. If you have a problem with something I’ve said, please quote my exact words that you disagree with, and indicate where you think I went off the rails.
All the best,
w.
The simple answer is that the political decided UNFCCC doctrine state that humans are driving the global temperature. Hence El Niño and La Niña, or any other circulation system, are not UNFCCC conform and ideological blasphemy?
Bill, I’ve heard the assumption that ENSO will balance out to zero many times, but I’ve never seen the supporting evidence for that assumption. You’ve made the statement that it has balanced out to zero since 1871.
Can you please provide a supporting link for that statement? In particular, I’m interesting in finding out WHAT balances out to zero. Is it the sea surface temperature in the NINO 3.4 area (ie. the sea surface temperature hasn’t changed in over 140 years), or is it the net energy released by the ENSO cycle has balanced out to zero (in which case how was that net energy release calculated for the first part of the record)?
I’m sure you know exactly what you mean, but for a layman like me it’s very ambiguous and most of the time the ‘zero balance’ comment comes over as an assumption, not a fact as you’re stated it is.
rgbatduke says:
January 17, 2013 at 9:29 am
“And we will never succeed in doing so at the same time we make energy more expensive and discourage its use. The poverty in question is energy poverty. Fundamentally. With enough, cheap enough, energy, we can make the deserts bloom, create jobs in the heart of Africa or India or South America, bring medicine and electric lights and running water to the world. Cheap, clean energy solves all problems; it is the fundamental scarcity.”
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Absolutely correct. The best way to make poor people into rich people is to supply cheap energy. The best way to make rich people into poor people is to make energy more expensive. Energy is work and work not done by a device has to be done by a person. Give people energy and they can spend their time improving their life instead of just living it.
Energy is the golden bullet that will fix everything. Only the power-hungry collectivists want that bullet to stay in the gun.
rgb at 1:31 pm – Yes. Excellent. Follow the money. Big energy definitely benefits by the CAGW scare.
As an Engineer, I think that it’s a mistake to describe it as a regulating mechanism. Such implies a predetermined target.
It’s a multi-modal system that operates in different quasi-static states depending on the available energy flux (power) entering the system, driving the temperatures of parts of the system to and beyond threshhold levels. That flux is dominated by insolation (solar energy reaching the surface) but the temperature is also (notionally) influenced by thermodynamic state and the magnitude of currents and circulations, both horizontal and vertical.
The strength of circulation is determined by global factors. The dominant polar circulation around Antarctica is moderated after the big chill at the tip of South America by mixing from both Atlantic and Indian Oceans, before entertaining the Pacific. Again, the America’s stand in the way of a free circumpolar circulation and some colder waters must be diverted along the East coast towards the Equator. Fluid mechanics says that the stronger the circulation, the greater the diversion and therefore the mixing in the Pacific. What could “drive” such a stronger circulation are greater contributions of heat from the Atlantic and Indian Oceans; by them being “warmer”. i.e. The consequence of them being warmer is that the Pacific becomes cooler.
One could model such things as multi-body resonances, taking into account the enthalpies involved and the resulting time constants of the various oscillations. But …
The real world is of course far more complicated. There are for example biogenic factors reacting to changes in temperature that cannot be ignored, affecting surface albedo, ozone levels and cloud formation. And thene there’s the moody sun.
I doubt that we’ll ever know enough to be able to model the climate system sufficiently to be reasonably predictive on the decadal scale and longer.
Willis, your speculation, just like Bob Tisdale’s and others, is just way off the mark. There are thousands of articles about El Nino, by many people who think they are climate experts, that amount to little more than blind men trying to guess what an elephant is. They each have a piece of it but don’t know where to put it. I explained the physical basis of ENSO in my book two years ago but somehow you and everybody else did not bother to read it. ENSO is an actual physical oscillation of ocean water involving equatorial currents in a large bowl called the Pacific Ocean. The system is not triggered by temperature but by trade winds. When you blow across the end of a glass tube you get its resonant tone, determined by the dimensions of the tube. Trade winds are the equivalent of blowing across the end of a tube and the ocean answers with its own resonant tone – about one El Nino wave every five years. This is its natural period and on that time schedule It raises and lowers global temperature by half a degree. Trade winds first pile up warm water in the Western Pacific between the Philippines and New Guinea. That piled-up water is the Indo-Pacific Warm Pool, the warmest water on earth. Between the two equatorial currents driven by the trade winds is the equatorial counter-current. When enough warm water has piled up gravity flow begins east along that equatorial counter-current. An El Nino wave traveling salong the counter-current can be observed by satellites. When it hits the South American coast it spreads out north and south by approximately twenty degrees. As the warm water it picked up from the Indo-Pacific warm pool spreads out it warms the air above it. This warm air rises, interferes with the trade winds, joins the westerlies, raises global temperature, and we know an El Nino has arrived. But any wave that runs ashore must also retreat. As the El Nino wave retreats sea surface behind it is lowered by half a meter, cool water from below wells up, and a La Nina has started. As much as the El Nino raised global temperature La Nina will now lower it. This heat exchange can be very precise. There were five El Nino peaks in the eighties and nineties according to satellites, with La Nina valleys in between. The temperature went up and down by half a degree but the mean temperature did not change and random deviations from the mean were less than 0.05 degrees in an eighteen year period. The returning El Nino wave joins the equatorial currents whose temperature drops as seen by satellites. This is because of the upwelling of cool water in their wake. The spreading out of some water north and south in the Western Pacific is not part of ENSO but of the North and South Pacific gyres. What makes ENSO possible is the blockage of the equatorial currents in the Western Pacific that allows the Indo-Pacific Warm Pool to form that is the source of the El Nino wave. In the Western Atlantic Ocean the horn of Brazil deflects the equatorial currents, does not permit them to pile up water, and no oscillation is possible. If you look at global temperature curves you will notice that they are actually a concatenation of El Nino peaks and intervening La Nina valleys, with occasional irregularities caused by major oceanic events. This goes back as far as we have records. It is normal and talk of eradicating them is just plain stupid. ENSO has existed as long as the current configuration of equatorial currents has existed, which is to say since the Panamanian Seaway closed. And Nino3.4 is just a lucky guy, sitting in the middle of the equatorial countercurrent and watching all the El Ninos go by. And giving us advance noitice because it catches them before they get to South America.
Physical resonance? Given the size of the resonant chamber and the speed with which energy flows in the ocean tend to occur (currents, etc.) that’s perhaps the least-energy solution — 30 yrs round trip? When the Pacific was a different size, maybe the resonant period was different, too.
Willis,
I don’t necessarily have answers. But here is a picture of the current La Nina plume, pretty much in the 3.4 region. It doesn’t look like noise.