Guest Post by Willis Eschenbach
The best thing about doing climate science the way I do it is that I can study anything I want, and there is always so much more to learn … in the present instance, there’s another year of Argo data, so I thought I’d take another stroll through the world of Argo. The Argo floats sleep a kilometer down, and then every ten days they dive down another kilometer and slowly rise to the surface, measuring temperature and salinity as they go. Then they drop back down a kilometer, and go back to sleep. So start with, here a movie I made up that lets us go diving with the Argo floats down to 2000 metres and back up again …
Figure 1. Movie of the Argo temperatures at standard layers.
One thing I hadn’t realized was how the western sides of the oceans are generally warmer than the eastern sides. Makes sense, because the wind blows in that direction, piling up the warm surface water in the west, and as a result forcing warm water down to deeper levels … at least that’s how I interpret it. I was also surprised by how deep the warm water goes, it’s 18° or so down a couple hundred metres in many places.
The Argo floats are indeed a marvel, but they do have their limitations. One of the limitations is that there are only about 3,500 of them in the ocean at any one time, and the ocean is a very big place. As a result, I don’t know how much trust we can put in the results … but let’s look at them anyhow.
First off, here’s what’s going on at the surface. The data says that there is a small warming of about a tenth of a degree over the decade. But as with many things in climate, the reality is more complex. Here is a breakdown of the surface temperature into the seasonal and residual components:
Figure 2. Argo Surface Temperatures. Top panel shows raw data. Middle panel shows the average changes (seasonal component), month by month, as an anomaly. The bottom panel shows the raw temperature less the seasonal component, again as an anomaly.
Now, despite the fact that there is a trend visible, as detailed in the bottom of Figure 2, you can see that the temperature dropped from the beginning of the record in January 2005 to about January 2008. Then for two years, the temperature rose rapidly … and dropped again for the next two years, and then rose again to the end of the record.
Because of this variation, I’d say that drawing any conclusions from the apparent tenth of a degree per decade “trend” is very premature. Let me give you another example of this same problem. Figure 3 shows the temperature trends at the surface, in degrees per decade.
Figure 3. Surface temperature trends by area. Dark blue and green show cooling.
Now, there’s a number of interesting things about this map. First, most of the ocean isn’t doing a whole lot, either trivially warming (cyan) or trivially cooling (light green).
Next, there are isolated areas that are significantly cooling—off the southern tip of Africa, near China, down in the Antarctic, and most curiously, the North Atlantic.
Similarly, there are isolated areas of warming—west of australia, off of Japan, west of Panama, east of Argentina, and off the northeast US.
Finally, the tropics by and large is not warming in any significant manner. This is in line with my hypothesis that tropical clouds greatly constrain the temperature variations in the tropics.
Anyhow, that’s what I learned from looking at Argo. I learned once again that linear trends are always deceptive … and a lot besides that. Always more to find out in this field, I guess that’s why they call climate the “settled science” …
My best wishes to all of you, warm oceans and crisp evenings, and time with those you love,
w.
As always, let me request that if you disagree with someone, please QUOTE THEIR EXACT WORDS. This allows everyone to understand your objection
ARGO DATA: It’s big, it’s ugly, and it’s scattered, and you need to download July 2013 onward month by month. In any case, it’s here, as .ncdf files.
MY PREVIOUS POSTS ON ARGO, ordered by date.
Krige the Argo Probe Data, Mr. Spock!
A few weeks ago I wrote a piece highlighting a comment made in the Hansen et al. paper, “Earth’s Energy Imbalance and Implications“, by James Hansen et al. (hereinafter H2011). Some folks said I should take a real look at Hansen’s paper, so I have done so twice, first a quick look at “Losing Your…
The Argo floats are technical marvels. They float around below the surface of the ocean, about a kilometre down, for nine days. On the tenth day, they rise slowly to the surface, sampling the pressure, temperature, and salinity as they go. When they reach the surface, they radio home like…
Like Jason, I proceed into the unknown with my look at the Argo data, and will post random notes as I voyage. Come, my friends, ‘Tis not too late to seek a newer world. Push off, and sitting well in order smite The sounding furrows; for my purpose holds To…
Following on my previous post, “Jason and the Argo Notes”, just a couple of graphs in passing: Figure 1. Argo surface temperatures, northern hemisphere. Colors show the latitude of the floats, from red at the Equator to blue in the north. Click on image for full size version. UPDATE: several…
Argo and the Ocean Temperature Maximum
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…
I got into this investigation of Argo because I disbelieved their claimed error of 0.002°C for the annual average temperature of the top mile of the ocean. I discussed this in “Decimals of Precision“, where I showed that the error estimates were overly optimistic. I wanted to know more about what the structure of the…
Argo, Latitude, Day, and Reynolds Interpolation
This is another of my occasional reports from my peripatetic travels through the Argo data (see the Appendix for my other dispatches from the front lines). In the comments to my previous post, I had put up a graphic showing how the January/February/March data for one gridcell varied by latitude…
Bob Tisdale has discussed a variety of issues with the hemispheric and basis-by-basin Levitus summary of the ARGO data in his excellent post here on WUWT. I wanted to take a larger look at at the global ocean data, to provide it with some context. After following a variety of…
I’ve been thinking about the Argo floats and the data they’ve collected. There are about 4,000 Argo floats in the ocean. Most of the time they are asleep, a thousand metres below the surface. Every 10 days they wake up and slowly rise to the surface, taking temperature measurements as…
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
Willis, thanks for your posting of interesting and curious things. It is interesting that two areas that show warming also show low salt on the salt page http://www7320.nrlssc.navy.mil/GLBhycom1-12/navo/globalsss_nowcast_anim365d.gif The area off South America close to the Equator has had a strong upwelling of low salt water and the area North off the US and Canada also has a strong upwelling. That these two areas have strong upwelling is curious.
FASCINATING graphic, Mr. Engineer, thanks heaps.
This link is a charming blend of scientists and anecdote; https://www.youtube.com/watch?v=UbFTdiBa9cg
Willis, good choice with the map projections. The typical rectangular projections subtly influence perceptions so equal area maps are nice to see.
Thanks, Gary. I have no use for the Mercator projection for anything but marine navigation …
w.
just a thought about ARGO:
as it are free drifters there is a bias: Argo is a good measuring system for what is happening with the ocean currents and within them but as a whole sea temperature system? well not the perfect one but already better then the very unreliable pre argo measuring system
so yes to have a good idea of what happens ARGO is the new big thing and for sure it is a good addition to already existing measuring devices
unles you have an “all including depth and surface wondersensor” that can absolutely measure EVERYTHING we have to do it with a system that has it’s strength and weakness. Ships have the weakness of limits by the course they take and regularity of measuring on the same path but the strength that the measurements are current independant, ARGO has the strength to be with 3300 floats that keep track, but the weakness it drifts with currents and thus the bias from these currents.
howeven both provides us only samples and not the whole picture Yes oceans can really vary on short distances (the anomalies in the north atlantic in front of the northeast USA are showing that: it’s where the labrador current and gulf stream meet. any shift of that current will give these big anomaly contrasts on such a short distance. Research has showed that the gulf stream moves see this abstract
http://onlinelibrary.wiley.com/doi/10.1002/%28SICI%291097-0088%28199605%2916:5%3C559::AID-JOC26%3E3.0.CO;2-Z/abstract
Also changes in the AMOC (not to be confused with the AMO!!) can explain them easyly
With all that said i do believe ARGO is the best we have, not perfect but at least the first reasonable system to have a fairly good idea
however it is not the full idea
In regards to : “One thing I hadn’t realized was how the western sides of the oceans are generally warmer than the eastern sides. Makes sense, because the wind blows in that direction, piling up the warm surface water in the west, and as a result forcing warm water down to deeper levels … at least that’s how I interpret it. ”
I don’t agree, so can someone help me out? I used to spend summers on the east side of a large lake, It was was always warmer water on our side, because the surface water blew in our direction all day, most days (west to east). When we would ski and fall on the west side of the lake, the water seemed much cooler.
What I say is that the water flow is the key, not the wind. The cold oceans off California are due to water coming down the coast from Alaska…if the water ever got warmer than 70 degrees during a San Diego summer, it was heaven. Yet in Florida, the water comes up from the Gulf Stream down south. When I scuba dived in Key Largo, we never had to wear a wet suit or we would roast.
My interpretation is that it is not the wind, it is the stream direction..
And Horseshoe Crabs off of Cape Cod. Ah, the Gulf Stream, it is bath-like to my West Coast sensibilities … LOL!
Mike wrote: “My interpretation is that it is not the wind, it is the stream direction.” That is correct, but it is largely the wind that drives ocean currents. The trade winds push warm tropical surface water to the west until it hits a continent, then the current gets diverted along the coast, since it has to go somewhere. At higher latitudes, the currents go back to the east, then back toward the equator when a continent margin is reached. Hence warm currents off east coasts and cold currents off west coasts.
Whenever ARGO is discusssed one should bear in mind that the data must be viewed with caution, since the data has been adjusted to remove what was considered to a warming bias.
See http://earthobservatory.nasa.gov/Features/OceanCooling/page1.php
“CORRECTING OCEAN COOLING
On a Thursday evening in February 2007, Josh Willis stood in front of his laptop, his wife cajoling him to get ready to go out to dinner. He looked with a sinking feeling at the map he had just made. ….In 2004, Willis published a time series of ocean heat content showing that the temperature of the upper layers of ocean increased between 1993-2003. In 2006, he co-piloted a follow-up study led by John Lyman at Pacific Marine Environmental Laboratory in Seattle that updated the time series for 2003-2005. Surprisingly, the ocean seemed to have cooled….On blogs and radio talk shows, global warming deni*rs cited the results as proof that global warming wasn’t real and that climate scientists didn’t know what they were doing….”
The data was then “corrected” to remove what was perceived to be a warmming bias in the data.
In addition to that, the data set is too short, and there is a lack of spatial coverage such that no sensible and scientific conclussions can be drawn from ARGO regarding trending/changes in ocean heat content .
This is correct. Argo is another temperature dataset that has been adjusted upward to accommodate propaganda needs. Must always remember that. Where is “read ’em and weep” Mosher?
Thanks, Richard. In my opinion, Josh Willis’s correction was proper, because it was the result of a known and verifiable problem with the way that some of the Argo floats were measuring the data. So I disagree that the dataset was adjusted upwards “to accommodate propaganda needs” as mpainter says. It was adjusted because it was wrong.
Having said that, it doesn’t mean that all possible errors in the dataset have been identified …
w.
Willis, my understanding that the correction was based on observations of TOA energy balance which are of course, quite doubtful.
You seem to be saying that some floats were faulty and so were corrected. Are you sure of this?
Willis?
They claim that “the temperatures in the Argo profiles are accurate to ± 0.002°C.” If that is the case, why would they need to be adjusted at all? Were the adjustments greater than the margin of error? If so, wouldn’t that indicate that either the accuracy claims are highly exaggerated, or the adjustments were excessive?
Louis
They were adjusted because they showed that the oceans were cooling.
Tsk, tsk, what kind of thermometer is that? Cooling?
So they got out their theoretical physics and decided that measurements at the top of the atmosphere showed that the earth was keeping heat somewhere.
The oceans, right? Sooo-oo. Twiddle twiddle, there, fixed. And now Argo shows that ocean heat content is growing. Willis has bought into this, strangely enough. Twiddle twiddle suits him fine.
I take a different point of view.
mpainter, I agree that it looks bad. But I also understand why Willis doesn’t want to sign on to conspiracy theories. You’re reputation can get trashed if you don’t have enough proof. My point doesn’t depend on all that side history. I’m simply asking, how can anyone argue with a straight face that the Argo floats are accurate to ± 0.002°C and claim at the same time that the temperature readings are biased and need to be adjusted? That is just plain contradictory. It’s possible I’m missing something here, but that’s why I ask questions. I’m here to learn.
Louis
You have put your finger on the problem and that problem has to do with credibility, am I right?
As for myself, I believe that I have taken the correct measure of our NOAA data keepers.
mpainter January 22, 2015 at 9:47 am Edit
Sorry, mpainter, I spoke a bit inaccurately. There were indeed some argo floats that had problems. However, that wasn’t all of the problems. The Josh Willis correction had to do with the “XBTs”, the expendable bathythermographs. Some of them didn’t fall at the rate that they were believed to be falling. It’s all explained pretty well in the link that richard verney gave above.
However, as I said, there still are likely to be errors in the Argo data. As part of the same process Josh Willis identified some of them, viz:
It’s not clear, however, that all of the bad Argo floats have been identified. See, e.g. here.
The work continues,
All the best,
w.
Louis January 22, 2015 at 11:56 am
It turns out that the problems haven’t been with the temperature sensors, but with the pressure sensors. Suppose you want to know what the temperature is at a depth of e.g. 100 metres. As the float is rising, how do you know when to take the temperature? Well, you use a pressure gauge, and from that, you can calculate the depth … if you know the temperature and salinity of the column of water above.
The identified problems have been in the pressure sensors. Now, in many parts of the water column the temperature doesn’t vary much with depth, so in those parts it won’t be a significant problem. However, near the “thermocline”, where temperature varies quickly with depth, even a small depth error can lead to a significant temperature error.
So although the temperature sensors are quite accurate … the entire system is inter-related, so an error in either the pressure or the salinity sensor can cause significant errors in the temperature reading.
w.
And Louis, please, no conspiracies are necessary to explain warming of the brain. These types see warming everywhere, even if the data needs “rectification”.
Thanks for the response, Willis. Your quote of Josh Willis shows that once again it is the cool nail that gets hammered, never the warm one.
And I __mean__ never__.
Well Willis,
I have studied the NASA link that Verney provided and it appears that you have not really grasped what this is about which is entirely understandable because I’m not sure how well I do myself.
First of all, that NASA write up is a masterpiece of obfuscation. I say this as an old marketing and advertising man, and I know whereof I speak.
Nowhere do they say what the problems were except that the Argos were giving temperatures that were “too cool”. Otherwise the article rambles all over the place from sea level, thermal expansion, modeling, CSIRO, XBT (which, by the way, have nothing to do with the ARGO buoys as you supposed), satellite altimetry, TOA energy budget, etc., everywhere As I’ve said.
NOWHERE do they explain how the data were adjusted nor WHY it was needed except to say that the Argo data was “cool”.
In one revealing comment in the article, the complaint as given that “den*ers” were using Argo data to refute global warming.
I advise anyone who wants to see a masterpiece of science obfuscation to read this article at Verney’s link.
Willis writes “So although the temperature sensors are quite accurate … the entire system is inter-related, so an error in either the pressure or the salinity sensor can cause significant errors in the temperature reading.”
Quoting error margins on one component of a complex measurement process without regard to how those components interact borders on a fraudulent claim from the manufacturer. There’s a fine line between “fraudulent” and “marketing”.
Is there a chart/map which shows where at the present time these 3300 floats are located? Would they not eventually congregate in specific areas, because of the ocean currents?
ARGO’s home page:
http://www.argo.ucsd.edu/
3748 floats as of 22 Jan, 2014
Thanks, cool – thought I would post the graphic:
http://www.argo.ucsd.edu/statusbig.gif
BruceC: Minor correction- 3748 floats as of 22 Jan 2015, not 2014.
If you click on the “Where in the world is Argo” link at the end of the head post, I discuss the distribution of the floats. Here’s a graphic showing long-term distribution …
http://wattsupwiththat.files.wordpress.com/2012/02/argo-temperature-profiles-per-100000-sq-km.jpg
ORIGINAL CAPTION: Figure 2. Number of temperature profiles ever taken by Argo floats in various areas of the ocean. Percentages in the second row refer to the percentage of the total ocean area having that number of temperature profiles. Percentages in the third row refer to the percentage of the ocean area from 60°N to 60°S having that number of temperature profiles. Click on image for larger version.
w.
problem with that map is each dot must be about one hundred miles wide.
Yes, and I seriously doubt that each buoy does an adequate job of measuring that one-hundred mile “dot”.
And the area outside the “dot” is completely untouched.
Willis, What I see happening with surface temps, look like they are driven by upwind ocean temps, your notes
I think these led to swings downwind, and it will show up in the surface temperature record, and IMO it is this effect that ended up being interpreted in the temp record as global warming.
It’s noted above that min temps look to be going up, but not max temps. I see some of that as well, but when you look at a “thermal” cycle as your day (daytime warming following night cooling as the 24hr day), cooling is a match to previous warming, except for min temps, and they are all over the place, both up and down, large regional swings, that I think are from your isolated cold spots.
I’m with m painter that the most surprising thing about that fine movie is the amount of cold water at depth in the north Pacific and the way it fans down toward the equator. It looks like that water is leaking through the Bearing straits and sinking, or the NW Pacific is a more important area of deep water formation than we realize. The deep basins separating Greenland from North America also show as far more important outlets for Arctic bottom water than the more touted and shallower route past Iceland.
I’d sure like to see that as actual temperature rather than anomaly.
Gymnosperm:
One way to view it: the volume represented by the influx of the Gulf Stream into the Arctic ocean must displace an equal volume. This displacement must continue even during the polar winter. Where does the displaced water go ? Out through the Bering Straits? In part? Should be able to make some rough calculations based on Gulf Stream flow volumes, perhaps.
gymnosperm January 22, 2015 at 8:02 am
Huh? The movie IS actual temperature and not an anomaly …
w.
@tty 1/22 2:02am, RE: Contrariwise. The oceans contain a number of watermasses with different characteristics (including temperatures) and often quite sharp borders. Ask any submariner.
I am in 100% agreement.
The argument that Argo fails Nyquist sampling is powerful. Google wattsupwiththat Nyquist Argo for an education. An important one is George E. Smith’s March 2, 2014 3:46 pm. But George has many worth reading including what I think is the introduction of Nyquist into the argument: Jan 27, 2012 8:16 pm in the Decimals of Precision thread.
Willis’s Figure 1 is gorgeous. But let’s not forget that the geographically smooth temperature contours is a product of averaging over a full year. On any given day there are less than 400 temperature samples over the entire world at each level. Over a month there are less than 11,000 on any given level. The spatial variation is almost certainly undersampled resulting in an overconfidence in error bars.
Surface Temperatures on Jan 21, 2014 http://www.ssec.wisc.edu/data/sst/archive/15021sst.gif
Willis, please do me a favor and tell me where I can get the software to do the animation in your first figure.
If they’re going 2km down, how often do some touch bottom?
Figure 3 would be easier to read with light blue representing the -0.8 and light green representing +0.4.
Has Al Gore installed a giant heater at the mouth of the St. Lawrence river? That blob of major warming is spurious.
Re: fredberple at 4:37 am
Very interesting observation. “So, if the global oceans vary annually by 3/4 to one degree, why? Is this soley due to the eccentricity of the earth’s orbit and the variation is solar radiance or albedo from one pole towards the sun then the other with more land in the northern hemisphere affecting ocean temperatures. What is causing that annual variance? Maybe this has been covered before but I don’t recall.”
Oops Sorry. Should have looked more closely at the time scale. It isn’t annually. Appears to be due to axis tilt so the high temperatures are when the sun is over the equator and the low temperatures are at the solstices. I should have looked more carefully but interesting none the less. So the surface temperature of the ocean varies significantly with the angle of incidence of the sun on the earth? Or is it both angle of incidence and orbit? First peak appears to occur in January – perihelion with lag, the second in July after summer solstice. Why?
I see only one annual peak – the gridlines are at 1/2 years.
Crum, That is so mixed up, posted before editing, but still, why is there a double peak January and July?
Probably because the Sun crosses the equator twice a year.
Every other year is labelled on the graph. There is one peak a year, looks like February, a little after perihelion. The effect may be enhanced by that being SH summer and most of the ocean being in SH.
I’m confused ( it’s normal ) I thought maximum density of water is at 4 degrees C ?
So how come is colder than that deeper ?
Salt water and fresh water differ. Salt water reaches max density at freezing. Has to do with the electrolytes.
The maximum density of water at 4C is only for fresh water. At 4C salt water begins to lose the heat of hydration, about 3.6 kilojoules for each mole of salt, sodium chloride. The temperature goes below 0C before all the heat of hydration is gone. The sodium and chlorine ions play a game of musical chairs with the water molecules, attaching to different molecules, and will not let the water freeze until all the heat of hydration is removed. The 3.6 kilojoules of energy that must be removed before freezing is the reason most of the deep ocean is around 3-4C. Also, pure water under pressure will remain liquid at temperatures below 0C. Such water is called super cooled water.
hello old person 🙂
I’m having trouble with this and I’m not very knowledgeable about these things. Is it possible you can point me to some explanation will not take weeks to comprehend ? I do not have a proper picture in my mind what is going on. I think if things are falling the mass of the thing does not effect the rate of falling ?
but then a cold thing within the same thing falls because they are more dense ( take up less space in the medium ) Is that correct ? That is not gravity because the warm thing should fall the same as the denser thing ? there must be some repulsion from within the medium which the denser thing avoids ?
Fresh water gets denser as it gets colder because the molecules are closer together. At 4C small cluster of ice forms in the water. The ice does two things; it pushes the molecules of water apart and lowers the number of molecules in a given space and ice weighs less so the space taken up by the ice also lowers the weight. A simple way to say it would be that below 4C ice crystals in the water cause it’s density to be less. Salt water cannot start freezing because of the salt and it continues to get denser until it reaches it’s freezing point.
John, as you are obviously a man who enjoys learning, you might be interested in this recent new explanation for why water expands below 4°C …
w.
Willis, that is an interesting article. Currently, he has only a simulation. It will be interesting to see if he is able to test his theory. I read only the summary and it did not identify what would cause the bonds to shift when 4C is reached. I am sure we will hear more when he devises some tests.
Exactly. Willis has enormous interest in this area and we are fortunate that he openly shares his research with us. The difference between main stream climate science and Willis is that Willis openly acknowledges the limitations of the data he is working with.
If climate science could only more honestly communicate what is actually known, what is a work in progress, what is pure speculation and most importantly what their failures are. If one can’t admit failure all of their work becomes suspect.
Anyways these datasets and how they are collected are interesting, however I am not sure what conclusions if any we can draw from them.
Could someone explain why there is a “seasonal component” from a global ocean temperature data?
The seasonal component graph shows the peaks (local maximas) all hit around the end of January-early February. The local minimas are all around late Sept-early October.
Of course I realize there is much more ocean area in the Southern Hemisphere, so that then leads to the question of area weighting in the data. Is every grid treated equally? Are grids equal area?
Joel O’Bryan
January 22, 2015 at 11:14 am
Could someone explain why there is a “seasonal component” from a global ocean temperature data?
The seasonal component graph shows the peaks (local maximas) all hit around the end of January-early February. The local minimas are all around late Sept-early October.
There are two cycles that “almost” are in synch which other. But they are (during the past decades) quite separate from each other.
1. Solar TOA Radiation varies from 1408 watts/m^2 on January 5 down to 1316 watts/m^2 on July 5.
Contrary to the simplifications inherent within Trenberth’s flat “average earth” Disk World model, the earth is a sphere and it does rotate the sun in an elliptical orbit. Thus, solar radiation at top of atmosphere is NOT a nice, even average 1361.3 watts/m^2 all year. Rather, solar radiation hitting earth’s atmosphere is at its maximum when the earth is closest to the sun January 5 each year during the Southern Hemisphere summer, and is at a minimum in July each year during the Northern Hemisphere. Midway between January and July each year, it is near its average value. Today, 22 January, it is near maxium at 1405.
This SORCE solar radiation data can be approximated very closely (within a 1/2 watt/sec) by a cosine wave using Day-of-Year. Like any cosine wave, it is very flat across the peaks (changing only slowly with time in late December – early January and late June – early July) and is changing very fast when it crosses the axis (the average value) in March and September.
Keep this in mind in a few minutes.
2. The earth currently rotates on its axis at 23.5 degrees from the earth-solar plane. The sun is highest in the southern hemisphere on Dec 22 ( 14 days prior to solar radiation maximum) and is highest in the Northern Hemisphere June 22 (14 days prior to solar radiation minimum).
Geometrically, this means the sun appears to move across the sky from winter (very low in the equator’s direction on 22 Dec/22 Jun), to a midpoint when the sun’s movement crosses the equator on the equinoxes of Mar 22 and Sept 22, and then to a high point in mid-summer on Jun 22/Dec 22.
On the globe, the sun rises due east and sets due west with 12 hours of sunlight and 12 hours of darkness ONLY twice every year: on Mar 22 and Sept 22 at the equinox (“equal night” in Latin.) Every other day of the year, the sun rises and sets either further north of the equaotr, or further south of the equator.
On Dec 22, the sun is directly overhead at noon on the Tropic of Capricorn at -23.5 degrees.
On Jun 22, the sun is directly overhead at noon on the Tropic of Cancer at +23.5 degrees latitude. (Just south of Key West, FL)
So, why are there two peaks in the ocean’s temperature?
From Dec 15 through Jan 30, the solar radiation directly over the area between Latitude -30 and -17 is receiving solar radiation for the maximum amount of time possible through the shortest possible attenuating air mass possible at the highest possible solar elevation angle (least possible ocean albedo angle) at a time of year when solar radiation is at its maximum possible of the year. Every day the sun is going back over nearly the same track it had the previous day. The sun passes directly over Australia, just barely passes over the small triangle of south Africa, and crosses South America through Paraguay (south of Peru and most of Bolivia, just north of Argentina, and just kissing a bit of south Brazil. Very, very little land in this band. Almost all of the sun’s extra heat goes into the southern ocean water.
In March and September, the sun passes over the equator. Solar radiation at TOA is near average, nights and days are near equal most days – and “on average” over the whole month are 12 and 12. But the sun is moving rapidly during this time: It spends every day a little further north or south of its previous day’s path.
In June and July, the sun again travels a near-constant path over the earth up near +23.5 latitude. Again, air mass is near minimum, solar elevation angle is highest, and solar air mass is lowest (least attenuation in the atmosphere.) But, the solar radiation per second is lower this time. The sun is passing over an area with much more land mass, and that land mass divides the oceans into smaller areas. In fact, there are no major openings at all under the Tropic of Cancer between the west coast of Africa and Taiwan out past the east coast of China!
The Western sides of the ocean are warmer than the Eastern sides for the very simple reason that because of the coriolis effect, Northern Hemisphere surface currents circulate clockwise while Southern surface currents circulate counter-clockwise. What that means is that currents on the Western side bring warm water away from the Equator while the Eastern side brings cooled waters from the poles. See:
http://media-2.web.britannica.com/eb-media/57/70057-004-85830DA6.jpg
Except for the Indian Ocean where the Leeuwin Current [not shown in questionassumption’s figure] flows from the Pacific , across the north of Australia and down the Australian west coast. The Leeuwin Current is one of the reasons that southern Western Australia is much less of a desert than it might otherwise be [cf Kalahari Desert and western North and South America].
Fantastic piece of work again Willis.
For me its interesting that the upward trend shown in the lower panel of your figure 2 from year 2012 through 2014 does not go above the peak shown in 2010.
The reason its interesting is the claim from NOAA that 2014 is the warmest year. Also, the curve they show in their press releases does not have the same shape as other time series of temperatures such as RSS or UAH or Giss. These other curves show 2014 below the level for 1998 and 2010. I wondered if NOAA was justifying an upward trend towards 2014, and hence the “warmest year evah” based on oceanic data influencing a combined oceanic / land data set.
However, your work, Willis, suggests that the oceanic data has not reached a peak in comparison to previous years.
As said, other curves suggest the land data has not done so either, Therefore NOAA’s claim of 2014 being the warmest is strange. Exactly what data is it based upon?
Thanks again.
In figure 1, there is a large white area around Indochina and the Malay Peninsula. Is that an area that has no buoys?
The Argo buoy map shows no buoys in those areas; probably due to being too shallow. The Sunda Shelf for instance, is mostly only about 20m deep.
Indeed Willis, this is so true of all ‘specialist’ educational endeavor … knowing more and more about less and less until they eventually know everything about nothing !
Thanks, Willis. Very interesting article.
Argo is a fascinating experiment.
Your observation about the the warmth to depth in the west of each ocean basis is interesting. Obviously there is a mechanism. It could be prevailing wind as you suggest or it could be ocean current circulation as dictated by Coriolis forces carrying water from the poles in the east and towards the poles in the west.
Whatever that mechanism is however, an alternation in the functioning of that mechanism represents a plausible means by which the oceans at depth could warm. If the strength of prevailing winds changes or if ocean currents speed up or slow down then that would effect the temperature gradient you have observed. Of course what warms the west would cool the east, so to first approximation this would seem to involve no overall change in ocean heat content. However that is only a first approximation. I suspect that in reality things are not so well balanced.
One of the big problems of the “missing heat is hiding in the oceans” story is the lack of a plausible mechanism by which heat could be transported hundreds of metres down into the oceans. But are we not looking at such a plausible mechanism?