Guest Post by Willis Eschenbach
It has been known for some time that the “Pacific Warm Pool”, the area just northeast of Australia, has a maximum temperature. It never gets much warmer than around 30 – 31°C. This has been borne out by the Argo floats. I discussed this in passing in “Jason and the Argo Notes“, and “Argo Notes Part 2“. I’d like to expand on this a bit. Let me be clear that I am by no means the originator of the claim that there is a thermostat regulating the maximum ocean temperature. See among many others the Central Equatorial Pacific Experiment. I am merely looking at the Argo data with this thermostat in mind.
First, Figure 1 shows the distribution of all of the ~ 700,000 surface temperature measurements taken by Argo floats to date.
Figure 1. A “histogram” shows how many data points fall in each of the 1°C intervals shown along the bottom axis. The maximum is in the interval 28°-29°C.
The number of temperature records peaks around 29°C, and drops quickly for temperatures above 30°C. This clearly establishes the existence of the mechanism limiting the oceanic temperatures.
What else can the Argo data tell us about this phenomenon? Quite a bit, as it turns out.
First, a look at the year by year evolution of the limit, and how it affects the temperatures at different latitudes.
Figure 2. Annual temperature variations measured by all northern hemisphere argo floats that exceeded 30°C. Temperature observations are colored by latitude. Click on image for full-sized graphic.
A couple points of interest. First, the cap clearly affects only the warm parts of the year. Close to the equator, that is most of the year. The further from the equator, the less of the annual cycle is affected.
Second, the majority of the breakthroughs through the ~30° ceiling that do occur are from areas further from the equator, and are short-lived. By and large, nobody exceeds the speed limit, especially those along the equator.
Figure 3 is a closeup of the years since 2005. I chose this starting point because prior to that the numbers are still changing due to limited coverage. To show how the mechanism is cropping the tops of the warmer parts of the year, I have added a Gaussian average (129 point width) in dark gray for each two-degree latitudinal band from 0°-2°N up to 10°-12°N.
Figure 3. Annual temperature variations measured by all northern hemisphere argo floats that exceeded 30°C. Dark lines have been added to highlight the average annual swings of the data by latitude band. Click on image for full-sized graphic.
As you can see, the warm parts of the yearly cycle have their high points cropped off flat, with the amount cropped increasing with increasing average temperatures.
Finally, here is the corresponding plot for the southern hemisphere:
Figure 4. Annual temperature variations measured by all southern hemisphere argo floats that exceeded 30°C. Click on image for full-sized graphic.
Note that there is less of the southern ocean that reaches 30°C, and it is restricted to areas closer to the equator.
Next, where are these areas that are affected by the temperature cap? I had always thought from the descriptions I’d read that the limitation on ocean temperature was only visible in the “Pacific Warm Pool” to the northeast of Australia. Figure 5 shows the areas which have at some point been over 30°C.
Figure 5. Locations in the ocean which are recorded at some time as having reached or exceeded 30°C.
Figure 5a. A commenter requested a Pacific-centered view of the data. We are nothing if not a full-service website.
Clearly this mechanism operates in a wider variety of oceans and seas than I had realized, not just in the Pacific Warm Pool.
Finally, here is another way to consider the effect of the temperature maximum. Here are the average annual temperature changes by latitude band. I have chosen to look at the northern hemisphere area from 160 to 180 East and from the Equator to 45°N (upper right of Figure 5, outlined in cyan), as it has areas that do and do not reach the ~ 30° maximum.
Figure 6. Average annual temperature swings by latitude band. Two years (the average year , shown twice) are shown for clarity.
Note that at say 40°N, we see the kind of peaked summer high temperatures that we would expect from a T^4 radiation loss plus a T^2 or more evaporative loss. It’s hard to get something warm, and when the heat is turned down it cools off fast. This is why the summer high temperature comes to a point, while the winter low is rounded.
But as the temperature starts to rise towards the ocean maximum, you can see how that sharp peak visible at 40°N starts first to round over, then to flatten out at the top. Curiously, the effect is visible even when the temperatures are well below the maximum ocean temperature.
Speculations on the mechanism
I want to highlight something very important that is often overlooked in discussions of this thermostatic mechanism. It is regulated by temperature, and not by forcing. It is insensitive to excess incoming radiation, whether from CO2 or from the sun. During the part of the year when the incoming radiation would be enough to increase the temperature over ~ 30°, the temperature simply stops rising at 30°. It is no longer a function of the forcing.
This is very important because of the oft-repeated AGW claim that surface temperature is a linear function of forcing, and that when forcing increases (say from CO2) the temperature also has to increase. The ocean proves that this is not true. There is a hard limit on ocean temperature that just doesn’t get exceeded no matter how much the sun shines.
As to the mechanism, to me that is a simple question of the crossing lines. As temperature rises, clouds and thunderstorms increase. This cuts down the incoming energy, as well as cooling the surface in a variety of ways. Next, this same process moves an increasing amount of excess energy polewards. In addition, as temperature rises, parasitic losses (latent and sensible energy transfers from the surface to the atmosphere) also go up.
So … as the amount of total radiation (solar + greenhouse) that is warming any location rises, more and more of the incoming solar radiation is reflected, there are more and more parasitic losses, more cold water and air move from aloft to the surface as cold wind and rain, and a greater and greater percentage of the incoming energy is simply exported out of the area. At some point, those curves have to cross. At some point, losses have to match gains.
When they do cross, all extra incoming energy above that point is simply transferred to the upper atmosphere and thence to the poles. About 30°C is where the curves cross, it is as hot as this particular natural system can get, given the physics of wind, water, and wave.
I make no overarching claims for this mechanism. It is just one more part of the many interlocking threshold-based thermostatic mechanisms that operate at all temporal and spatial scales, from minutes to millennia and kilometres to planet-wide. The mechanisms include things like the decadal oscillations (PDO, AMO, etc), the several-year Nino/Nina swings, the seasonally opposing effects of clouds (warming the winters and cooling the summers), and the hourly changes in clouds and thunderstorms.
All of these work together to maintain the earth within a fairly narrow temperature band, with a temperature drift on the order of ± 0.2% per century. It is the stability of the earth’s climate system which is impressive, not the slight rise over the last century. Until we understand the reasons for the amazing planetary temperature stability, we have no hope of understanding the slight variations in that stability.
My regards to you all,
w.
UPDATE (by Anthony):
Dr. Roger Pielke Sr. has some praise for this essay here:
Willis,
Thanks for another very interesting post on the Argo data. I found the seasonality displayed in your Fig. 6 quite interesting. As you know, the number of data recordings in the northern part of the sector that you selected in Fig. 5 is very sparse. By my eye, I don’t see any buoys above about 40N. Am I missing something?
Richard M : But, you really did discount the similarities of the planets without a lot of consideration (at least that is how it appeared to me).
Here is where an exact quote and an explication of your view would help.
In this post Willis has presented an extensive analysis of much data. In the previous article he was dismissive of a nonlinear model with 4 parameters fit to 8 data points. There is no inconsistency between them. If you were referring to some other inconsistency, point it out with exact quotes.
Philip Bradley said @ur momisugly February 13, 2012 at 2:16 pm
Popper’s claim was that observation statements are theory-dependent. When the theory is falsified, then observation statements dependent on that theory can no longer be made. Faraday’s observation statement was that the motor worked. When his, or Ampere’s theories of how electricity works were falsified, then it should have become impossible to make the statement: “Faraday’s motor works”.
Willis Eschenbach says:
February 12, 2012 at 11:03 pm
The advantage of being a professional scientist is I don’t have to break my concentration by a day job that involves pounding nails. That’s not to say I don’t pound nails. I do. But I do it to relax and get my mind off my day job which is math and science. My carpentry projects are about as amateurish as your attempts at math & science. I’m sure we’re both proud of what we do be we shouldn’t delude ourselves into thinking we excel at things no one will actually pay us to do. No one will hire me as a carpenter, Willis, and no one is going to hire you as a scientiest. I think we both know that but one of us won’t admit it.
Septic Matthew says:
February 13, 2012 at 1:25 pm
You have to begin from first principles. In this case a first principle is that nothing except additional incoming energy can raise the temperature of something above its S-B blackbody temperature. The S-B blackbody temperature is an ideal which is impossible to obtain in nature. Things are cooler than S-B blackbody temperature because nothing in nature is a perfect absorber of energy. Nature is populated with gray bodies that can never quite absorb all the energy that falls upon them thus they can never quite attain that ultimate maximum temperature.
The earth is a gray body and it only absorbs about 60-70% of the energy falling upon it from the sun. Lots of things, things like greenhouse gases for instance, can help it absorb more of that energy but nothing can make it absorb more than 100%.
Willis, not being a scientist or having any formal science education, I note calls the 255K S-B temperature of the earth it’s blackbody temperature. This is wrong. That is its gray body temperature assuming that the surface, on average, absorbs 70% of the energy coming in from the sun. This 70% figure is a gross estimate and no has yet been able to satisfactorily give it a precision of better than +-3% and no one knows how much it varies from year to year.
The energy in our climate system is determined in the short and intermediate time scales by the earth’s albedo. Over the long haul it’s determined by where the sun is in its evolution. The sun is about 10% hotter now than it was a few billion years ago (this is called the “faint sun paradox” because it makes us wonder what kept the earth from freezing in the past). A few billion years into the future the sun will turn the earth into a cinder. In the meantime arguing about the effects of anthropogenic CO2 on the climate is about the same as arguing about how many angels can dance on the head of a pin.
Willis, some maths for the rate of evaporation of saline, based on empirical observations and fully cited.
http://www.actis.com.au/evaporation_rate_of_brines.pdf
@Willis
“Yes, it is absorbed in the first 10 microns of the water … but the same is true about where it is absorbed in rocks, trees, kids, houses, and the land in general. Nobody thinks that LWIR can’t heat kids because it is absorbed in the first 10 microns of their skin.”
Yeah, and not even a kid would to keep cool in the summer heat by spraying themselves with sand. Rocks don’t evaporate under normal circumstances. Water does. Therein lies one of the major differences, among others, in the difference in physical properties between rocks and water.
@Willis
“Yes, it is absorbed in the first 10 microns of the water … but the same is true about where it is absorbed in rocks, trees, kids, houses, and the land in general. Nobody thinks that LWIR can’t heat kids because it is absorbed in the first 10 microns of their skin.”
Yeah, and not even a kid would try (more than once) to keep cool in the summer heat by spraying themselves with sand. Rocks don’t evaporate under normal circumstances. Water does. Therein lies a major difference, among other major differences, in the physical properties of rocks and water. Another difference would be why we have steam engines but not rock engines. I could go on but I doubt it would do any good.
Here is something to think about;
http://www.unm.edu/~cstp/Reports/H2O_Session_2/2-1-Hightower.pdf
surfactants lower the evaporation rate of water, so would increase temperature.
Lars P. says:
February 13, 2012 at 11:15 am
Lars, that all sounds wonderful until you look at the numbers.
Michael says that the missing 320 W/m2 needed to balance out the ocean heat budget are going away upwards as evaporation.
Unfortunately, the amount of evaporation is fairly well constrained, and is known to be on the order of 80 W/m2. What’s happening to the other 240 W/m2?
In addition, if DLR is not warming the ocean, then WHAT IS.
We know the ocean on average receives about 170 W/m2 from the sun.
We know the ocean loses about 100 Wm2 to sensible and latent heat.
We know the ocean is losing an average of ~ 390 W/m2 through radiation (mental note, I can check that against the Argo data.
Net losses? Just under half a kilowatt per square metre, 490 W/m2.
Net gains without DLR? About 170 W/m2.
So … if DLR isn’t making up the difference, why isn’t the ocean frozen?
w.
Septic Matthew says:
February 13, 2012 at 12:37 pm
Out-freakin’-standing. That’s exactly the kind of model you need to model the climate. Please, everyone take a look at the temperature regulation going at that link. When a hot spot springs up, clouds and thunderstorms bring cold air and water from aloft to cool it down. See my post about “The Details are in the Devil” for some considerations on analyzing the kind of system shown at Held’s site.
Can’t thank you enough, Matthew, that’s going in the bookmarks.
‘w.
Willis says,
“Man, you “ad-hominem” guys never take a break, do you? I don’t care if it was found written on a bathroom wall. If it’s true, then it’s true, and thus it is worth paying attention to, whether Holmes is fictional or not.
Unless, of course, you are arguing that one should indeed theorize without facts … and in that case, even Sherlock Holmes couldn’t help you.”
As others have pointed out, whether you theorize first or second doesn’t matter, as long as you follow the facts. Who did I ad hom by the way? Doyle? Who cares? It’s true anyway.
Konrad says:
February 13, 2012 at 12:39 pm
Konrad, thanks. I’ll pass on the experiments until you can answer my question. If (as you claim) DLR is not providing the missing ~ 320 W/m2 of energy to the ocean, then what is the source of the energy that keeps it from freezing?
Answer me that, and we can move on.
w.
Robin Hewitt says:
February 13, 2012 at 12:52 pm
Oh, dear me, no, I’d love to be that good but I’m not. As my daughter is fond of saying, “In your dreams, dad”.
However, I am indeed having fun. Glad you are enjoying it.
w.
Septic Matthew says:
February 13, 2012 at 1:25 pm
Here’s what I think. The phenomena of interest are taking place on the minute and hour scales, and not on the month or year scales.
It took me years to realize this. I was looking for something that would control the climate on the scale of millennia. One day I thought … wait a minute. If there is something that keeps the temperature from going over 30° every day, it will mean that the temperature will not go over that in a week, a year, or a millennium. I felt like an idiot.
It is the cropping of the daily peaks that creates the capping effect on temperature. I have shown in “It’s Not About Feedback” the mechanisms involved. I have provided the evidence for the mechanisms in “The TAO That Can Be Spoken“.
As you point out, it is still possible for increased forcing to increase average temperature, by increasing the area or the time at or near the peak.
However, the amount of that increase will be much, much less than it would be in the absence of that mechanism. It’s an uphill fight, and the hill gets steep fast as temperature increases.
Remember that this is the crossing of curves, not something that kicks in at 30°. The same effects are happening at 29°C, but to a lesser amount. So it’s not like the temperatures lower than 30° are free to rise. They too have to struggle to increase the temperature due to increasing clouds, thunderstorms, albedo, and parasitic losses.
Thanks for the question,
w.
hmccard says:
February 13, 2012 at 3:16 pm
There are hundreds of buoys in that area. The graph only shows those locations that have been above 30°C. All of the data in Figure 6 came from those hundreds of buoys. In the whole area … hang on …
OK. I just wrote the program to calculate it. The area 0-45°N, 160-180°E shown in Figure 6 has 28,899 observations from a total of 518 different floats over the period of record.
w.
Joules Verne says:
February 13, 2012 at 4:26 pm
Joules, I knew you’d show up to attack me. You have nothing to contribute, so you come to claim that I’m no good as a “scientiest”, as you so quaintly put it.
Funny, Nature magazine thought enough of my scientific worth to publish my “Communications Arising” on Lake Tanganyika. Peer reviewed, don’cha know … have you had anything peer-reviewed and published in Nature?
And the peer reviewed Blackwell journal “Diversity and Distributions” just published another piece of mine …
So why should I care what some anonymous troublemaking internet popup jerkwater thinks of my science? Nature and the journals think it’s good enough, and many scientists who (unlike you) are willing to sign their names to their opinions think my work is good, and that’s good enough for me.
Thanks for showing up to snarl, though, Joules—it’s helpful for people to be reminded that you are only here to cause trouble.
w.
Willis Eschenbach says:
February 13, 2012 at 6:27 pm
Konrad, thanks. I’ll pass on the experiments until you can answer my question. If (as you claim) DLR is not providing the missing ~ 320 W/m2 of energy to the ocean, then what is the source of the energy that keeps it from freezing?
Answer me that, and we can move on.
/////////////////////////////////////////////////////////
Willis,
I do not claim to know what source of energy other than Luna tidal, geothermal and solar would be heating the oceans. I have little trust in Trenberthian radiation cartoons and cannot be sure that energy is in fact missing. However I do trust empirical results. LWIR has a very limited effect on water that is free to evaporatively cool. If you restrict the evaporative cooling of two warm water samples allowing only conductive and radiative cooling and expose the surface of one sample to LWIR you will notice a distinct divergence in the rate of cooling between the samples. When evaporative cooling is allowed, both samples cool faster yet there is no divergence in their temperatures. Whatever energy is keeping the oceans from freezing, I am sure DWLWIR has little to do with it. The lack of a hypothesis from me about what energy sources keep the ocean liquid should not be a barrier to you conducting this simple experiment to rule out DWLWIR as the energy source.
Willis writes “I’ve added the following to the head post:”
Thanks Willis. It is an interesting figure and I wonder how it will change over the years as we get more data.
Willis Eschenbach says:
February 12, 2012 at 10:52 pm
R. Gates says:
February 12, 2012 at 9:30 pm
… Ocean heat content is probably the best single metric for the energy imbalance of the planet. The amount it has gone up (to as deep as we are currently measuring) over the many decades is impressive.
Thanks, R. Gates. Not sure what you call impressive. We’ve been measuring ocean temperature down to 2,000 metres for about half a century. During that time, as best as we can tell, the temperature of the ocean has increased by eight hundredths of a degree.
Can’t say I’m all that impressed by that myself …
w.
________
I won’t quibble with that number as I am not sure where you got it, but based on the actual energy content that the ocean has stored since around 1970, (that we are able to measure – and it’s a “travesty” we can’t measure more accurately even deeper), the ocean down to about 2000 meters has stored roughly 23 x 10^22 Joules of energy. I think your 30C cap on surface temps (with slightly higher temps in a few select locations) offer an interest clue about how the ocean could be taking in energy faster than it can get rid of it. There are undoubtedly multiple factors keeping the peak ocean temps around 30C at the equator, not the least of which is obvious air temperature and pressure, but there is no similar governor or cap on how fast energy can be transferred to the ocean, as we have seen, it continues to go up, and indeed, with the huge heat sink that the ocean is, the funnel for energy into the ocean is far bigger than the smaller funnel for it to escape.
I’d be interested to see what you know about regions such as the Mindanao Dome near the Philippines. Of course, during La Nina years, such as now this region experiences a large buildup of warm water, and the Ekman transport carries this warm water down to at least 2000 meters, and of coure it is a major recharge point for the Pacific Warm Pool that eventually works back toward the east leading to the next El Nino. There are several points around the world’s oceans where such warm water downwelling from occurs, and so those who argue about LW radiation not being able to warm water deeper than the top surface fail to understand the powerful downwelling that occurs at areas such as the Mindanao Dome, taking down large amounts of warm equatorial water from the surface to deeper layers of the ocean.
Konrad says:
February 13, 2012 at 7:40 pm
OK, so your claim is it’s not DLR but you don’t know what it is.
I rarely refer anyone to RealClimate … but you really should look at the experiment that they describe there. Unlike yours, it’s an experiment done on a real boat (M/V Tangaroa) on a real ocean looking at real variations in downwelling real longwave. They used thermometers good to a tenth of a degree, measured the actual ocean temperature, and guess what?
They found the ocean does in fact absorb DLR. Hard evidence.
So until your experiment is more real-world and more precise than that, and given you can’t offer any other reason the ocean isn’t freezing, I’m gonna go with the Tangaroa results. These show the ocean can indeed absorb DLR.
Sorry,
w.
Here’s what I think. The phenomena of interest are taking place on the minute and hour scales, and not on the month or year scales.
And that is the flaw in the Forcings model/theory and why its predicted accumulating heat in the Earth’s climate is in all likelyhood not happening. The heat isn’t ‘missing’. Its long gone to space, transported by fast H2O feedbacks.
Willis: Here’s what I think. The phenomena of interest are taking place on the minute and hour scales, and not on the month or year scales.
I think you are basically correct, but there is the in-between scale of 1 – 5 days or so. That should not be ruled out, in my opinion.
R. Gates says:
February 13, 2012 at 8:24 pm
Yes, that’s exactly where I got the number of degrees, 0.08°C, eight hundredths of a degree. Here’s how.
Take the total joules over the fifty years.
Divide it by fifty to give joules/yr.
Divide it by square metres of ocean to give joules/m^2/year.
Those joules/m2/year are heating 2,000 cubic metres of ocean. Multiply that by say 62/60 to give tonnes per square metre.
It takes 4 megajoules to heat a tonne of water 1°C.
SO … 4 megajoules/tonne times 2,066 tonnes means it will take 8,266 megajoules to raise that square metre of water 2,000 metres deep by 1°C.
We know how many joules/m2/yr it will take to raise the water 1°C.
We know how many joules/m2/yr we have.
Divide one into the other, we get 0.08° temperature rise … call me underwhelmed.
w.
Willis: Can’t thank you enough, Matthew, that’s going in the bookmarks.
I am glad you like it. I don’t know how much time you want to spend reading articles, but some of the articles referenced in that thread do begin to address the effects of CO2 changes on the time scales that interest you and me.