TAO Sea and Air Temperature Differences

Guest Post by Willis Eschenbach

The TAO buoy array is an array of moored buoys in the equatorial tropical Pacific ocean. Here’s a map showing their locations along with the average sea surface temperature.

tao triton buoy location plus sst

Figure 1. Locations of all active and historical TAO buoy sites.

And here is what a typical buoy setup looks like:

tao triton moorings overview.png

Figure 2. Details of the TAO moored buoy and sensor arrays.

I like the TAO buoy data because we can be sure that it is free of urban heat islands, changes in location, instrumentation changes, and many of the other problems that plague land-based stations. It is also measured very frequently, typically every ten minutes. This lets us explore the daily cycles of air and sea temperature, solar radiation, longwave radiation, humidity, and the like.

The eight buoys located on the Equator between 165°E  and 95°W have the most data covering the longest time, so I’ve looked most at those locations.

The coldest of these eight buoys is the one at 95° W longitude, near the Americas at the far right of the map above. Average sea surface temperature (SST) there is 23.8°C (75°F). The warmest is the buoy at the other side of the Pacific at 165° East longitude. Average SST there, near the warmest part of the Pacific, is 29.2°C (85°F).

Now, something that I like to look at and consider are the differences between the buoys. The buoys at the colder eastern edge of the Pacific are often different from the buoys at the warmer western edge of thePacific. Here are the daily air temperatures from each of the eight buoys:

TAO daily cycles temperature

Figure 3. Daily cycle of air temperatures at eight equatorial TAO buoys.

Next, here are the same eight buoy air temperature records, expressed as anomalies about their respective means.

TAO daily cycles temperature anomaly

Figure 4. Daily cycle of air temperature anomalies at eight equatorial TAO buoys.

Note that the daily air temperature cycles at the warmest buoys (reds) have a very different shape and amplitude than do the coolest buoys (blue), particularly during daylight hours.

I’ve mentioned before that what I like best about science is getting surprised by what I find. Here’s my surprise for today. I got to thinking about what is called “delta T”, usually written as “∆T”. The “delta” means “difference”, and the “T” means temperature. For example, winds on the ocean are often driven by temperature differences.

One of the important ∆T’s in the climate system is the difference between the surface temperature and the air temperature. Over the ocean, the air is generally cooler than the sea surface. When the difference between the surface and the air temperature (∆T) gets large enough, when the ocean gets significantly warmer than the air or the air cools significantly below the sea temperature, we start to see things like cumulus clouds and thunderstorms.

So let me start with the absolute values of the differences between sea surface temperature and air temperature at the eight TAO buoys. I’ve used the same color coding as above. Light blue is the coolest buoy at 95°W, and red is the warmest buoy at 165°E.

Temperature Differences sea minus air raw TAO buoys.png

Figure 5. Daily cycle of differences between sea temperatures and air temperatures at eight equatorial TAO buoys.

This was the first surprise. The overall difference between the sea temperatures and the air temperatures was not in any order by temperature. The coolest and the warmest buoys had the widest differences between sea and air temperatures … odd.

But the real surprise came when I plotted the delta T values as anomalies around their respective means, as I’d done in Figure 4 above …

temp diff anomaly sst minus air TAO buoys.png

Figure 6. Daily cycle of anomalies of differences between sea temperatures and air temperatures at eight equatorial TAO buoys.

How interesting. All along the Equator across the Pacific, from the cold edge to the warm edge, the sea-to-air temperature difference anomaly is just the same in every location—lowest at eight AM, peak at one PM, trough at five PM, peak at six PM, trough at nine PM, highest point at about three in the morning.

Not only that, but the temperature swings have the same amplitudes, to within a few hundredths of a degree. Given that these are eight totally different results from sixteen independent temperature datasets (eight air temperature, eight sea temperature), this is an astounding degree of agreement.

I must say that I do not have any coherent explanation for the afternoon and evening peaks and troughs. All I can conclude from this is that all across the Equatorial Pacific, the daily temperature swings are strongly constrained by some unknown combination of natural phenomena, such that the average daily swings are identical in both timing and amplitude regardless of the average temperature of the location …

Go figure … the joys of settled science.

w.

AS ALWAYS: Let me politely request that when you comment, you QUOTE THE WORDS YOU ARE DISCUSSING so that everyone can understand just what you are referring to. I can defend my own words. I can’t defend your vague restatement of something you think I said. Quote what you are talking about, it’s the only way to refute what someone says.

FURTHER READINGS: Here are some of my previous posts about the TAO buoy data:

The Tao That Can Be Spoken … 2011-08-14

As I mentioned in an earlier post, I’ve started to look at the data from the TAO/TRITON buoy array in the Pacific Ocean. These are an array of moored buoys which collect hourly information on a variety of environmental variables. The results are quite interesting, because they relate directly to…

Pinatubo and the Albedo Thermostat 2011-08-21

I got to thinking that the eruption of Mount Pinatubo should provide a good test case for my theory that changes in albedo help regulate the temperature and keep it within a narrow range. When a big volcano erupts, it throws both black and reflective particles and aerosols high into…

TAO/TRITON TAKE TWO 2011-08-25

I wrote before of my investigations into the surface air temperature records of the TAO/TRITON buoys in the Pacific Ocean. To refresh your memory, here are the locations of the TAO/TRITON buoys. Figure 1. Locations of the TAO/TRITON buoys (pink squares). Each buoy is equipped with a sensor array measuring…

Cloud Radiation Forcing in the TAO Dataset 2011-09-15

This is the third in a series ( Part 1, Part 2 ) of occasional posts regarding my somewhat peripatetic analysis of the data from the TAO moored buoys in the Western Pacific. I’m doing construction work these days, and so in between pounding nails into the frame of a building I continue to…

TAO Buoys Go Hot And Cold 2015-06-16

I got to thinking about how I could gain more understanding of the daily air temperature cycles in the tropics. I decided to look at what happens when the early morning (midnight to 5:00 AM) of a given day is cooler than usual, versus what happens when the early morning…

 

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107 thoughts on “TAO Sea and Air Temperature Differences

  1. Excellent detective work Willis. About your finding:

    “the daily temperature swings are strongly constrained by some unknown combination of natural phenomena, such that the average daily swings are identical in both timing and amplitude regardless of the average temperature of the location …”

    Maybe there’s some unnatural constraint to what these buoys are recording? This is so remarkable that one might wonder if these things are preprogrammed to get this result. Have no idea why that would be done but given what else has been and is being faked it would not surprise me.

    • Again, most informative Willis. I would guess that the pattern match of the average daily swings can be explained by heat transfer physics. ie the rate of heat transfer (by both radiative effects and state change (evaporation / condensation) do not vary from day to day and from time to time. Changes to temperature requires that heat moves, how much heat energy changes places and the thermal capacity factor or the materials (water, air, vapor) completely controls how much.

      • Interesting report Willis. I doubt the data is being tampered with, but agree with NW sage that the patterns show processes controlled by physics. Willis, your fig. 6 suggests that these pertinent physics laws do not care for your descriptions of “cold edge” and “warm edge”, or “coolest” and “warmest”. Evidentaly there is some threshold over which things behave similiarly. Maybe if another set of buoys existed at higher latitudes we would see different daily profiles?

    • I might suspect early morning heating of the atmosphere causes cloud formation and early morning rain showers. A similar phenomena is occurring in the later afternoon. Combined with surface winds this might explain the air temperature wave form.
      When in the tropics we experienced almost daily brief rain showers almost every day at about 10:30 am local time. They lasted about 15 minutes and cooled the air significantly, then the humidity would again begin to rise and clouds would form again in the afternoon only to dissipate by sundown.

  2. An excellent paper without a doubt. From this base if the same exercise was run over the same buoy set but say at one yearly intervals would the TAO buoys pick any mappable trends?

  3. Great analysis. Strong inference of equatorial temperature hysteresis. No such thing in the CMIP5 climate models. Inferentially, another reason they produce a non-existant tropical troposphere hotspot.

    • A view from the frequency domain might be interesting. Somewhat resembles the ringing in a high Q lowpass filter.

    • If the modeling were accurate, would equatorial temperature hysteresis be an input to the models or an output? My first thought is that it’d likely be an output, but I don’t know enough about the internals to be sure. Might it be actually be there in the outputs, but no one has looked for it?

      My impression is that understanding those models is a lifetime project. Not a project that I’m either prepared to or interested in undertaking.

  4. I do not live on the ocean but when I spend extended periods in the outdoors I have noticed that winds tend to peak and subside at certain times of the day. Since the wind has an influence on evaporative cooling it would be interesting to compare typical wind speed throughout the day to that temperature plot.

  5. I have been studying similar land-based data profiles and comparing hourly air and soil temperatures and solrad data, a current case being Lewistown MT with a 46 degree latitude.

    During the day the sun warms the soil. The soil absorbs energy and after sunset the soil stays warmer than the air all night.

    During January the 100 cm soil stays much warmer than the air almost all month. The 5 cm soil is warmer than the air 80% of those hours.

    During July the 100 cm soil runs about 40% of the average air temperature throughout the month. The 5 cm soil heats up as fast as the air but cools much more slowly. Once the sun sets the air cools quickly while the warmer air cools slowly.

    The temperature at 100 cm barely moves.

    The top 100 cm of the soil acts as a thermal surge tank, soaking up solar gain and heating the air when the sun goes down. In January the soil is almost always warmer than the frigid air.

    Most of all I see absolutely ZERO evidence of downwelling “back” radiation warming the surface.
    288 K – 255 K = 33 C warmer with an atmosphere is completely bogus, there is no physical evidence of “back” radiation warming the surface. When these two scenarios collapse they take the entire RGHE theory with them.

    Happy to share my data, Excel sheets and graphs. Just need instructions. FTP site?

    Quality Controlled Data Sets: monthly/daily/hourly w/ column explanations
    https://www.ncdc.noaa.gov/crn/qcdatasets.html

    8,000 views, ZERO rebuttals.

    http://writerbeat.com/articles/14306-Greenhouse—We-don-t-need-no-stinkin-greenhouse-Warning-science-ahead-

    http://writerbeat.com/articles/15582-To-be-33C-or-not-to-be-33C

    http://writerbeat.com/articles/19972-Space-Hot-or-Cold-and-RGHE

    http://writerbeat.com/articles/16255-Atmospheric-Layers-and-Thermodynamic-Ping-Pong

    http://writerbeat.com/articles/15855-Venus-amp-RGHE-amp-UA-Delta-T

    • Back radiation exists as is obvious from basic physics. However normally it only decreases the upward heat flow from the ground a bit.

      • I don’t buy the “decreasing heat flow” claim about “back radiation”. Perhaps you might venture into describing this mechanism in detail to convince me.

        Unless the emissivity of what is being back radiated to changes, I just can’t see the mechanism, and I do not think that “back radiation” changes the emissivity of what it encounters.

        I think that “back radiation” joins the flow of the upward radiation, because it already has the energy of the upward radiation, and so it can do nothing to increase or decrease the upward.

    • Most of all I see absolutely ZERO evidence of downwelling “back” radiation warming the surface.

      Nick,
      A few years ago during 2008 there was a live data stream from the automatic weather station (AWS) based on Dome Argus in Antarctica. The AWS located there measured temperature both above and below ground (the ice surface) in a continuous daily record. Three sensors measuring air temperature were placed at elevations of +4 m, +2m & +1m while three more sensors, placed at sub-surface depths of 0.1m, 1 m & 3m, measured the ice temperature in the ground.
      The location of the Dome Argus AWS at latitude: 80 22″ 02’S, longitude: 77 32″21’E and with a surface elevation of 4,084m provided a unique insight into the climate of East Antarctica. During the austral winter of 2008 Dome A was in darkness for 24 hours a day from sunset on 16th April 2008 at 0725 UTC until sunrise on 26th August 2008 at 0556 UTC. During this period of 142 days Dome Argus receives no direct sunlight and the temperature sensors of the AWS recorded the night time cooling as the high level ice surface radiated heat to space through the thin dry winter air.
      The winter weather at this location operated in two basic modes (either calm or stormy). During calm periods of no wind the 3 air sensors showed a persistent temperature inversion with the 1m elevation sensor typically recording values 15C lower than the air at the 4m elevation. The still air temperature was never constant, instead it varied in a pattern with a pulse of more than 24 hours, but all 3 sensors varied in unison and the temperature inversion persisted. During these calm periods the 0.1m ground sensor maintained a temperature 10C above the 1m air temperature but it dropped in value slowly and consistently showing both the effects of radiative cooling to space of the ice surface and that the daily air temperature variations were damped out by the thermal inertia of the ice.
      The transition to the stormy mode of weather at Dome Argus would typically take place over 24 hours. All three air sensors would drop in value and then the lowest sensor would begin to climb in value as the chilled air mixed and warm air from above 4m heated the lowest levels of the inversion. At the end of the mixing phase all 3 sensors recorded an almost identical value with a slight remaining inversion profile of less than 1C. Some 24 hours after the mixing started and the air temperature profile had equilibrated then the sensors would record a fall to a uniquely low value as the storm pulse reached its maximum before the temperature sensors recovered in value recording a rise in temperature of the mixed air as the storm passed.
      Because of its unique winter location we can be sure of the following features of the weather at Dome Argus.
      1. No direct solar heating by sunlight can possibly have occurred at this time during the depths of winter.
      2. The crestal elevation of the site means that all advected surface air that reaches here must be cooled by adiabatic lift.
      3. The residual summer heat in the ground ice cannot be heating the air at 4m because of the thermal inversion caused by radiative cooling at the surface of the ice prevents direct thermal contact.
      4. So the only source of energy that can maintain the higher air temperatures at 4m and above, in calm conditions, is the heating of descending air from aloft by adiabatic auto compression.
      5. Not only does the warm air aloft not heat the ground by back radiation at Dome Argus it is clear that the radiation of energy directly to space from the solid ice surface is the dominating mechanism of climatic control and that it is this energy loss from the solid surface that cools the air.

      • As a matter of fact in inland East Antarctica in winter you don’t really have any convection-dominated troposphere. The radiation-dominated stratosphere comes right down to the surface.
        Since there is practically no water vapor in the atmosphere it is also the perfect place to measure the greenhouse effect of increasing CO2. Oddly enough nobody seems eager to try.

      • 1, 3 and 5, I agree
        “2. The crestal elevation of the site means that all advected surface air that reaches here must be cooled by adiabatic lift.”
        I disagree. To cool, It just need contact with cold surface
        4. So the only source of energy that can maintain the higher air temperatures at 4m and above, in calm conditions, is the heating of descending air from aloft by adiabatic auto compression.
        I disagree. You don’t even need to explain the “higher air temperatures at 4m and above”, since you have a ready explanation for the cooler air at 1m (contact with cold surface)

        This doesn’t disprove back-radiation, which can actually be observed with a basic photometer looking upside.
        It just proves that the back-radiation is lower than upward radiation (which also can be observed with the same photometer)

      • As a matter of fact in inland East Antarctica in winter you don’t really have any convection-dominated troposphere. The radiation-dominated stratosphere comes right down to the surface.

        tty,
        I used to think that too, but Fig 1. in this paper by Pan, W et al. 2002 The temperature structure of the winter atmosphere at South Pole clearly shows the presence of a winter tropopause at an elevation of 8km at the South Pole.
        So like it or not the ice surface of East Antarctica, even in winter, is still in the troposphere. Other comparative planetology studies of atmospheres elsewhere have shown that a planet’s tropopause is determined by atmospheric pressure rather than air temperature. See Robinson, T.D. & Catling, D.C. (2014) Common 0.1 bar tropopause in thick atmospheres set by pressure-dependent infrared transparency.

      • 4. So the only source of energy that can maintain the higher air temperatures at 4m and above, in calm conditions, is the heating of descending air from aloft by adiabatic auto compression.
        5. Not only does the warm air aloft not heat the ground by back radiation at Dome Argus it is clear that the radiation of energy directly to space from the solid ice surface is the dominating mechanism of climatic control and that it is this energy loss from the solid surface that cools the air.

        I’m not sure how much there is, but it will also get the energy from any condensing WV. But it would have to be refreshed to some extent, as it’s a consumable.
        Also, if these are clear sky readings, what I have found is the sky is radiating at probably below -70F or -80F at least, I see -80F zenith temps in Ohio.
        So on ice, I would think it will be reflecting that cold surface, I can see it here when I measure snow at 20F below air temps, and I know below the surface it not frozen. I think that would have a big influence to your 1m temps.

      • tty,

        in inland East Antarctica in winter you don’t really have any convection-dominated troposphere.

        True, but what we do have is some very impressive weather. Unfortunately earth.nullschool does not have any displays for 2008 to match my Dome Argus data but this example from June 2014 shows typical winter weather at Dome A (the location of the green ring).

        Let’s have another look at Fig 1 in Pan, W. et al. 2002. The vertical temperature profile in May and June clearly shows that, above the surface inversion layer associated with the radiative cooling of the ice surface, there is a fall in temperature as height increases, a standard feature of a troposphere, namely a vertical lapse rate. But there is no insolation at the South Pole in winter and so no radiant energy to heat the ice surface and cause buoyancy driven atmospheric convection. So how is this lapse rate maintained? Certainly not by convection in its usually accepted sense of the upward. vertical transport of atmospheric properties.
        A digression:-
        The word convection is clearly related to the term convex used in optics to describe the shape of a bulging lens that is thickest in the middle. Convection in Meteorology therefore relates to the upward bulging of the atmosphere that we observe in the formation of cumulus clouds, we see a similar process of upward vertical bulging in a lava lamp. In optics the opposite of convex is concave; a lens that is thinnest in the middle. Cave, cavity & cavitation are all related examples of words used to describe an enclosed space, a hollow, or a gap from which material has been removed.

        What we observe on the ice plateau of east Antarctica in winter is a vigorous process of thermal cooling of the ice surface by radiative heat loss to space through the transparent infrared atmospheric window. This cooling demonstrates that solid surfaces are the most efficient thermal emitters, because solids can transmit flexural shear waves, whereas fluids and gases cannot. Solid surfaces are therefore more efficient thermal radiators than gases because it is the process of flexure that determines if a gas molecule can intercept and emit infrared radiation, something that only polyatomic molecules can achieve.
        The cooling of the air at ground level in East Antarctica creates a dense air mass that is then advected down slope off the ice plateau as a vigorous katabatic wind. Consider a stack of cards from which the lowest card is continuously been removed, the stack will fall into the cavity generated at its base. We can describe this as a process of concavetion, the vertical falling of air into the “cavity” created both by the radiative cooling at the ground surface and the associated lateral advection that exports the cold dense basal layer to the side as a ground hugging wind. Concavetion is therefore the opposite of convection and is a process driven by ground surface cooling rather that ground surface heating.
        It is the process of concavetion, the downward vertical motion of air in the polar vortex, falling under gravity towards the ice surface that causes the descending upper air to loose potential energy and to gain heat by adiabatic auto compression, thereby maintaining the observed lapse rate in the winter air above the South Pole.

      • Philip Mulholland

        What we observe on the ice plateau of east Antarctica in winter is a vigorous process of thermal cooling of the ice surface by radiative heat loss to space through the transparent infrared atmospheric window.

        1. What equation (and what constants (or values for water vapor, pressure, relative humidity, and 2 meter (?) air temperature ) do you use for that LW radiation loss from ice surfaces in the Antarctic icecap?

        Seems you couldn’t use the sea-level values for anything since the air pressure is so low at 3000+ meters? My interest is specifically sea-level values for Antarctic sea ice (and southern ocean open water) radiation losses but I’m hoping your equations can be adopted for the altitude difference.

        2. If the earth’s shape is actually a flattened geoid several kilometers shortre at both poles than at the equator, then why is the air pressure (at either pole at sea level) the same as at the equator? Even in Death Valley (CA), Rift valley (Africa), and Dead Sea (Is.) the air pressure is higher than at equal places at sea level at the same latitude. Or, is there a greater “equalizing” effect because the air falls “down” to the sea level around Antarctica by gravity (as well as the more widely recognized “cold air falls down syndrome), but then is pushed out away from the continent edges towards the equator as an aid to the adiabatic winds from the high cold interior icecaps?

      • RACook, you say:

        If the earth’s shape is actually a flattened geoid several kilometers shortre at both poles than at the equator, then why is the air pressure (at either pole at sea level) the same as at the equator?

        First off, you’ll need a citation for your claim regarding polar and equatorial air pressures.

        Second, the force of gravity varies as the square of the distance. The radius of the earth is ~ 6380 km. If the radius goes down by two km at the poles, the force of gravity will decrease by 0.06%, that is to say six hundredths of one percent …

        So no, you won’t see any perceptible difference in either your weight or the weight of the air column at the poles. Both will decrease by six hundredths of one measly percent …

        Best regards to you,

        w.

      • RACookPE1978
        In Britain it is a common feature of our clear sky still air winter weather that at night ground frost forms before air frost does. I have a set of temperature profile data charts that I collected from the live transmission data from Dome Argus between 17th May and 17th December 2008. I wanted to observe the generation of cold air and the formation of katabatic winds. The formation of the cold air inversion layer, its disturbance, removal then rapid reforming that is recorded on the charts is testament to the powerful radiative cooling to space of the ice surface. My observations are based on my interpretation of the recorded temperature data, but it is clear from the charts that as the winter develops the sub surface ice temperature at 1m progressively drops from -57C in May (with minor low amplitude recovery associated with the warmth from mixed air storms when the air temperature at +1m occasionally rises above the ice temperature) to a minimum of -63C in September (which is after the first sunrise on 28th August). After the period of 24 hours daylight (that starts on 16th October) the 1m temperature values recover to reach a value of -57C on the 17th Dec (my last record). Because the main temperature recovery of the ice only occurs following the last sunrise during the period of 24 hours daylight, I deduce that the heat loss from the ice in winter is predominantly from the previous summer’s stored solar heat.

    • nickreality65 January 24, 2018 at 5:14 pm

      Did you observe any rise in Surface temperature during the night phase at all?

  6. “I must say that I do not have any coherent explanation for the afternoon and evening peaks and troughs. All I can conclude from this is that all across the Equatorial Pacific, the daily temperature swings are strongly constrained by some unknown combination of natural phenomena, such that the average daily swings are identical in both timing and amplitude regardless of the average temperature of the location …”

    And people wonder how we can sparsely sample the ocean and be so confident.

    • And people wonder how we can sparsely sample the ocean and be so confident.

      Actually I wonder how one can be so confident if one only has measurements at the equator.

      • Greg F January 24, 2018 at 6:06 pm

        Actually I wonder how one can be so confident if one only has measurements at the equator.

        Since I made no claims about anything but the equatorial Pacific, why would such even sampling and such similar results from independent datasets not inspire confidence about what’s happening at the Equator?

        w.

      • Willis,
        I was responding to Moshers dubious extrapolation. Other than that I think what you found is quite interesting.

    • Steven Mosher January 24, 2018 at 5:40 pm

      “I must say that I do not have any coherent explanation for the afternoon and evening peaks and troughs. All I can conclude from this is that all across the Equatorial Pacific, the daily temperature swings are strongly constrained by some unknown combination of natural phenomena, such that the average daily swings are identical in both timing and amplitude regardless of the average temperature of the location …”

      And people wonder how we can sparsely sample the ocean and be so confident.

      Thanks, Steven, but I fear that is a false parallel. In this case, I’m showing identical results across about seven thousand miles (11,000 km) of ocean. Usually, different parts of the planet have very different thermal regimes and cycles. In this case, to my shock, they’re all nearly identical. That is extremely rare in my experience.

      On the other hand, measuring say the temperature of the ocean is a very, very different matter. The temperature domain is very different in different parts of the ocean. Often there is little correlation between nearby areas, with clearly defined temperature boundaries … and at other times there is strong long-distance correlation.

      Ask any process engineer how many thermometers you’d need to determine the average temperature to half a degree in say a swimming pool which is constantly being heated and cooled by a variety of processes in a variety of locations around the pool …

      Next, this is ten-minute data. It’s not one temperature every week. It’s a hundred and forty-four measurements every day.

      Finally, and unlike say the Argo floats or the scientific expedition temperature measurements, the TAO buoys are taking their measurements in one fixed spot.

      For all of those reasons, your comparison to other sparse samples of the ocean is not applicable.

      Folks are invited to read my post “Decimals of Precision” for a further discussion of this question …

      w.

      • Willis;
        Are the time stamps for the temperature readings based on local time or Greenwich time? I don’t understand how the extreme east and west ends appear to be in sync while the sun is at such different relative elevations for each location.

      • Thank you Willis, expressed much more eloquently than I could have. The daily Variability is not what is at issue in conjunction with the long term trends.

    • No Mossshhher the once Great and Powerful, people wonder how anybody can claim to take the land temperature records, slice, dice, adjust and homogenise them and keep a straight face when announcing the world’s temperature to one of more decimal places and calling it the BEST

  7. “How interesting. All along the Equator across the Pacific, from the cold edge to the warm edge, the sea-to-air temperature difference anomaly is just the same in every location”
    There is a reason for this. The sea absorbs, at some depth, about 160 W/m2 solar as a global average – it’s probably 200 or more at the Equator. All that heat has to exit via the surface. It’s a function of solar irradiation, so should be much the same along the equator.

    Now heat flux generally follows, and is proportional to, a temperature gradient or differential. It’s a bit more complicated with radiation or evaporation , but still the case that if a body is gaining heat and has to get rid of it, it will get warmer. So the sea-air temperature differential is basically determined by the heat flux that has to cross. That of course has a daily cycle. But it doesn’t much depend on where you are or how warm the air is. The solar input is much the same, as its the daily cycle.

    • Aren’t we talking about the oceans, a large body of moving liquid, not a large hard body. Water in an around these buoys is not standing still either horizontally or vertically.

      • Well, you should take that up with Willis, as it basically says you can’t learn much from TAO buoys, and Willis rightly says that you can.

        My point is that a certain total flux of heat must move upward across the surface over time, and to make that happen there has to be a temperature differential approximately proportional to the flux, and it doesn’t matter very much where you are on the Equator for that. That is what Willis is observing.

      • You do my head in at times Nick your statement is gibberish

        1.) heat flux is a vector it is a magnitude and a direction
        2.) By definition it forms a temperature gradient along the direction of the vector .. to be precise you get a dQ/dt along the direction

        Then you say this stupidity

        but still the case that if a body is gaining heat and has to get rid of it, it will get warmer.

        First it gets a lot warmer if it doesn’t getting rid of the heat :-)
        Second your statement is rubbish it depends if there is a sink absorbing the heat or the heat exchange process is constrained by physical exchange mechanisms.

    • But we are told it is global warming due to increased CO2 in the atmosphere that is causing the oceans to heat up and kill corals and cause fish to move elsewhere. It is definitely not the sun (so the alarmists say with their settled science).

    • Nick Stokes: ” … still the case that if a body is gaining heat and has to get rid of it, it will get warmer”

      What if the rate of dispersing heat is greater than the rate of “gaining heat”? Does the planet Mercury continue to get warmer since it is continually gaining heat from the sun?

      • “What if the rate of dispersing heat is greater”
        Then it will cool down. This is just the way heat transfer works. Temperature adjusts to keep the balance.

      • Thanks for your reply Nick, you said: “Temperature adjusts to keep the balance.”

        I agree. That’s why claims like this (found in a subsequent article):

        “heat … was being sequestered in the Pacific Ocean”

        are nonsensical right?

  8. What would be really interesting is to see the variation of the curves in different seasons, different Enzo conditions, different points during the solar cycle, etc. you might stumble onto a lot of surprises.

  9. Pretty easy to explain actually, the graph is the difference between sea surface and air temperature, during the afternoon from 1 to 6 pm the air temperature increases at a faster rate than the water temperature, mostly due to the enthalpy difference.

    • Air temperature increases rapidly because it is less dense. Same thing happens on land. The light air heats and cools quickly, the dense soil heats and cools slowly.

      It’s specific heat capacity, Btu/lb-F. Air 0.24 Btu/lb-F, water sensible, 1.0 Btu/lb-F. Water has the added impact of latent heat, 1,000 +/- Btu/lb at CONSTANT TEMPERATURE!!!!

      O&M&E 500 MW Rankine plants and these physical parameters becomes second nature.

      • You are so so right nickreality65:

        Most of the climate discussions relate to radiation matters and the Rankine Cycle barely gets a mention. Meanwhile, as gaseous water is lighter than dry air it rises, together with large amounts of energy up past CO2 etc with a proportion reaching the Tropopause, dissipating it’s energy on the way, all at CONSTANT temperature at the micro level; as you rightly say. And then it all comes back down again having dissipated that energy, ready to repeat the cycle.

        This atmospheric Rankine Cycle provides the global thermostat and mops up minor changes in the radiation budget by altering its cycle rate; just as a steam engine goes faster wihen the heat is increased, without temperature change.

        I look in vain for references to this Cycle amid the literature and comments.

        Weird, as it is so obvious to we engineers.

        PS: Love the old money!

        Regards.

      • it rises, together with large amounts of energy up past CO2 etc with a proportion reaching the Tropopause, dissipating it’s energy on the way, all at CONSTANT temperature at the micro level; as you rightly say. And then it all comes back down again having dissipated that energy

        That sounds like the mainstream assessment that forgets about this thing called gravitational potential energy. The energy isn’t lost as the air rises, it is converted to gravitational potential energy and redistributes that energy as kinetic energy wherever it falls.

  10. Do these buoys have wind data? If you plotted the data relative to GMT there would be a temperature gradient between adjacent buoys. Might that cause some of the pattern you saw? I live near the coast and there’s often swings from onshore to calm to offshore around sunset.

    • Vertical convection is the result of a temperature differential between the surface and air above it.This is greatest at or around midday and midnight and least in the dawn and dusk.

      It provides time delayed negative feedback to that differential. I suspect that is what is being seen.

  11. Salinity goes up as you go Westward. (due to evaporation)
    Increasing salinity means it takes more energy to evaporate water.
    More energy means higher temp.

    And it is difficult to de-couple the effect of salinity from the SST profiles.

    • Good point. Latent heat of vaporization also changes with temperature.
      Not only do the underlying thermodynamics change, so too do the kinetics, which will have an effect on observed temperatures.

      • The RATE of evaporation decreases at a given temperature as salinity rises because the salinity reduces vapour pressure but the latent heat of vaporisation (the amount of energy needed to part the water molecules) remains the same. That amount of energy is determined by atmospheric pressure and nothing else. Other factors only influence the RATE of the phase change.

        The surface temperature will rise over more saline water because less evaporation means that there is less assistance for the surface cooling that otherwise results from dry convective overturning.

        Over land, temperatures rise higher than over water because there is no evaporative cooling assisting the cooling which results from dry convective overturning.

        For a planet with no water vapour to assist surface cooling the dry convective overturning cycle must run faster so as to get energy back to the surface in descending air fast enough to enable the surface to radiate to space as much as it receives from space.

        However, both wet and dry scenarios have the same average surface temperature if atmospheric mass, gravity and insolation are the same.

        It is just that for a water planet the assistance supplied by water vapour means that a less vigorous convective overturning cycle is required.

  12. Fascinating, and I am not qualified to even hazard a guess on why the pattern is so consistent across such great geographic distances.

    It implies that some local air and water variables that “common sense” says SHOULD matter obviously don’t.

    You would think that things like wind speed, wave height, cloud cover, precipitation, humidity, air pressure, upwelling or downwelling currents, etc would play a role in this, since these variables can not possibly be consistent across such a vast area. (I wonder if the pattern changes with the sun angle?)

    I can’t think of any constraining weather mechanism that could act fast enough to produce such identical results, therefore you might be just looking at a simple heat transfer constraint between the two mediums?

    Would you get the same pattern indoors in a lab with a small amount of water and a variable heat source? It should be easy to test….

  13. Good stuff Willis!

    We keep being told we can’t determine anything in a “non-linear, chaotic, blah blah blah climate system.”

    And we keep finding simple new truths that amaze and delight us!

    As I wrote below:
    “Not all that complicated, is it, for a “non-linear, chaotic, blah blah blah” climate system?”

    https://wattsupwiththat.com/2017/10/04/cooler-global-temperatures-ahead-indications-are-that-la-nina-is-returning/comment-page-1/#comment-2627440

    [excerpt]

    Tropical Pacific Ocean temperature (e.g. Nino3.4 area) increases tropical humidity and temperature ~3 months later, and global humidity and temperature ~4 months later.

    Not all that complicated, is it, for a “non-linear, chaotic, blah blah blah” climate system?

    References – Allan MacRae and Bill Illis:
    https://wattsupwiththat.com/2017/09/15/report-ocean-cycles-not-humans-may-be-behind-most-observed-climate-change/comment-page-1/#comment-2613373
    https://wattsupwiththat.com/2017/09/20/from-the-the-stupid-it-burns-department-science-denial-not-limited-to-political-right/comment-page-1/#comment-2616345

  14. Willis, all I could see when I looked at the graphs you posted was your thunderstorm hypothesis. Temps build up, thunderclouds form, temps drop, build up, drop,

    Put this together with everything else you have done on energy transference in the Pacific tropical zone.
    It make more sense than anything else I have seen

  15. “I must say that I do not have any coherent explanation for the afternoon and evening peaks and troughs.”
    Willis, have you sought an explanation from any relevant scientists ?.

  16. Q: Why hasn’t some ambitious and clever pre-doc or post-doc had the curiosity, imagination, and initiative to check this out? Or to check out the score of other matters Willis has thought deserved a closer look? It would or could have got him/her a published paper and/or a PhD.

    A: They’re drones, bon étudents (sp?), stamped out like bottle caps on the academic assembly line. The persons who built science’s reputation were Willises—inquisitive, autonomous, capable, undogmatic, nullis-in-verba types. Today, in climatology and in other branches of science dominated by dogmatism (see Henry Bauer’s book thereon), it’s mostly or too-muchly verba.

    Foundations, which could be a counterweight to academia, have failed to be such. As Mencken implied, philanthropists are even more lacking lacking in free thinking than the professorial.

    • correction to my last words: “than the professoriat.”
      Curse Apple’s impossible-to-remove correction system!

      • Roger,

        It is all already in the body of public knowledge via the fact that boiling (or evaporation) take place at a temperature that is primarily affected by pressure. The higher the pressure the more energy is needed to run the process and once that amount of energy is achieved the temperature does not rise further but rather the process accelerates instead
        Both boiling and evaporation are the same process of phase change from liquid to vapour but evaporation is from a surface alone whereas boiling involves a phase change within the body of the water mass.
        The temperature ceiling of the air above a body of water is a by product of atmospheric weight and the consequent downward pressure which supplements molecular attraction between water molecules such that more energy is needed to break the bonds.

      • Stephen: When I wrote, “Why hasn’t some ambitious and clever pre-doc or post-doc had the curiosity, imagination, and initiative to check this out?” my “this referred to Willis’s discovery (among others) that:

        Willis: Now, something that I like to look at and consider are the differences between the buoys.
        ………….
        How interesting. All along the Equator across the Pacific, from the cold edge to the warm edge, the sea-to-air temperature difference anomaly is just the same in every location—lowest at eight AM, peak at one PM, trough at five PM, peak at six PM, trough at nine PM, highest point at about three in the morning.

        Not only that, but the temperature swings have the same amplitudes, to within a few hundredths of a degree. Given that these are eight totally different results from sixteen independent temperature datasets (eight air temperature, eight sea temperature), this is an astounding degree of agreement.

        in other words, I was exasperated that up-and-coming climatologists lacked the curiosity and initiative to check out “differences between the buoys.” That should have been obvious. Your statement “It is all already in the body of public knowledge via the fact that boiling (or evaporation) take place at a temperature that is primarily affected by pressure.” is so beside-the-point that it’s almost off topic.

      • Unfortunately that version of ‘this’ was not in your post under reply so I took it that ‘this’ was the general underlying physical mechanism behind the basic observation that faster convection puts a cap on air temperatures above oceans.
        Even so, that pressure based mechanism is still relevant because it explains the similarity of buoy readings after adjusting for time of day and latitude.

    • Q: Why hasn’t some ambitious and clever pre-doc or post-doc had the curiosity, imagination, and initiative to check this out? Or to check out the score of other matters Willis has thought deserved a closer look? It would or could have got him/her a published paper and/or a PhD.

      The answer is quite simple! It’s been well-known for many decades among geophysical professionals that the heat capacity of water is much greater than that of air, resulting in generally negative air-sea temperature differences. The shape of the diurnal cycle of those differences is governed by the rate of heat transfer between ocean and atmosphere, modulated In the tropics by a characteristic diurnal pattern of cloud cover. PhD theses require more than a rehash of known processes.

      • I had read your reply to S. Wilde. What has been missed is the entire scientific thrust of my comment. Since the diurnal cycle of solar radiance is uniform throughout the narrow tropical zone and since the specific heat of water and air is virtually constant, that the diurnal cycle of air-sea temperature differences varies uniformly with longitude is not particularly noteworthy scientifically.

      • 1sky1 wrote:

        What has been missed is the entire scientific thrust of my comment. Since the diurnal cycle of solar radiance is uniform throughout the narrow tropical zone and since the specific heat of water and air is virtually constant, that the diurnal cycle of air-sea temperature differences varies uniformly with longitude is not particularly noteworthy scientifically.

        While it is true at the top of the atmosphere the “diurnal cycle of solar radiance is uniform”, this is absolutely not true where it counts, down at the sea surface. There, we get different cloud types, cloud colors, and amounts of aerosols which give us quite different diurnal cycles.

        In addition, some of the buoys are in the cool eastern end of the El Nino phenomenon, and some are in the warm western end.

        Finally, the buoys in the far west are well into the area where there is a hard limit on how much the ocean will warm, no matter how much sunlight it gets.

        And given all of that, yes, 1sky1, despite your abysmal ignorance of the tropical surface conditions and despite your heartfelt but unsubstantiated claims, in fact it is noteworthy that the diurnal cycle of ∆T is nearly identical across the entire Pacific equator.

        w.

        PS—you say that “the diurnal cycle of air-sea temperature differences varies uniformly with longitude” … read the head post again. The oddity is that the diurnal cycle does NOT vary with longitude, neither uniformly nor non-uniformly. Instead, it is identical across 7,000 miles of ocean.

      • 1sky1 January 26, 2018 at 4:40 pm

        What has been missed is the entire scientific thrust of my comment. Since the diurnal cycle of solar radiance is uniform throughout the narrow tropical zone

        1sky1, further to my comment, I just looked at downwelling solar at the TAO buoys in question. The 24/7 average downwelling solar at the surface at the TAO buoys are between ~ 250 W/m2 at the low end to ~ 280 W/m2 at the warm end. That’s a difference of over 10%. So no, it’s far from “uniform”.

        w.

      • [Y]es, 1sky1, despite your abysmal ignorance of the tropical surface conditions and despite your heartfelt but unsubstantiated claims, in fact it is noteworthy that the diurnal cycle of ∆T is nearly identical across the entire Pacific equator.

        What is nearly identical across the entire Pacific equator is the SHAPE of the diurnal cycle of ∆T, not the cycle itself, which manifests clearly varying mean values, as seen in Figure 5. Ironically, that variation of the mean is what the original post patently failed to attribute to longitudinally varying levels of local insolation at the surface. And there’s still no inkling that the uniformity of shape ensues, as I pointed out, from largely ∆T-dependent heat transfer driven by insolation “modulated In the tropics by a characteristic diurnal pattern of cloud cover.” Poor Willis, who assumes that his critics are as lacking in geophysical grounding as he is, can only resort to misrepresentations and ad hominems in defense of his own failures.

  17. It is all a matter of density and pressure differentials. The weight of atmospheric mass bearing down on the ocean surface sets the amount of energy required for the phase change from liquid to vapour.
    Once sufficient energy becomes available water vapour forms which leads to clouds and rain.

  18. Willis,
    An impression after a quick read (before the long study) is that you have refined the data to reflect the constancy of, or a primary dependency on, a physical factor like – but maybe not this one specifically – the thermal conductivity of typical ocean water.
    Other than that, one imagines a synthetic template making the data obedient to a model. The worry is that hundredth of a degree, which is hard to achieve in deliberate laboratory experiments intended to measure to that accuracy, let alone the open ocean. As usual, properly constructed figures on measurement uncertainty would have revealed this in the original data. Geoff.

    • Geoff,

      The primary dependency on a physical factor is the weight of the atmosphere. Just as water boils at a lower temperature at a greater height with lower pressure so the potential for evaporation at the surface is controlled by downward pressure.
      In both cases, once the phase change energy threshold is reached, there is no further rise in temperature but a change in the speed of the process (evaporation or boiling) instead.
      Willis’s thermostat hypothesis, which is itself a restatement of ancient observations, simply reflects the changes in the rate and timing of evaporation and subsequent condensation once the thermal threshold imposed by atmospheric weight has been reached.

      • So releasing billions of tonnes of CO2 we are increasing the weight of the atmosphere and this will lead to warming at the surface. WOW, wait till Mickey Mann gets his hands and Schmitt gets his mits on that idea !!

  19. I’d be tempted to play with the data – (1) look at SUM of air + water temps, and see how shape compares with difference, and (2) integrate the difference curves w.r.t. time. No reason – just curious…

  20. “I like the TAO buoy data because we can be sure that it is free of urban heat islands, changes in location, instrumentation changes, and many of the other problems that plague land-based stations.”

    Willis,
    please add the year, month or time interval of your data used. Was the time period influenced by El Nino? Thanks!

  21. Nice find Willis. Asked before reading , I would have expected the western Pacific to be more stable.

    The graph is clearly dominated by the diurnal cycle which tends to mask the rest. What does the residual look like if you subtract mean daily cycle? This may tell us something about the idea of using NMAT to “correct” SST etc. at least in this specific zone.

  22. At a guess the “plateau” or even slight rise in the early evening is due to decreased evaporation after sunset. The surface layer which has cooled slightly and become slightly more salty by evaporation sinks and is replaced by warmer water from below.

  23. Trying to make ‘layman’ sense of this, at first glance the 6 am trough corresponds with the low before sunrise and the 6 pm one with sunset and the midday peak seems to follows the angle of the sun through the day. That doesn’t explain the peak and trough after sunset.

    It would be interesting to cross reference wind speed (and perhaps humidity) data to see if there is any early evening change which follows sunset and perhaps causes the evening peak and dip.

    From the SST graph (as opposed to the air-sea temperature differential) there is very little in the way of a dip after 6.00pm so it looks as if the temperature differential is driven by changes in air temperature which makes me wonder about the wind speed and if this changes (for some reason) and creates the significant peak and dip in the temperature differential.

  24. Mr Eschenbach, one thing I have noticed on the Air/Sea Difference Graph is the the lowest one actually goes Negative 4 times, ie the Air is Warmer than the Sea?
    Is that correct?
    If it is correct it must mean that the Air is not moving the heat away from the surface as quickly as you would expect.

    I assume that the Time of day for the readings is the local time of day?
    Are all the buoys in very deep water?
    As the depth can have an affect.

  25. @Willis
    “The eight buoys located on the Equator between 165°E and 95°W have the most data covering the longest time, so I’ve looked most at those locations.”

    But map in Fig. 1 shows ten buoys distributed in the Pacific along the equator. Could you mark the buoys that you used? (Yes, I also looked at your ‘TaoTriton Take Two’ reference posting. But it also shows 10 buoys on the equator.)

    Questions:
    1. Why did you pick two consecutive days? Why not a larger, random sample, to help eliminate any possible bias?

    2. Did you investigate any buoy data at other locations? For example, the equatorial buoys in the Atlantic (“PIRATA”) and Indian (“RAMA”) oceans?
    https://www.pmel.noaa.gov/tao/drupal/disdel/

    Comment:
    Looking at your “first surprise” (Fig. 5), the coherence of the dT’s at widely separated locations does indeed suggest that these instruments are somehow in “lock-step”. For example, between 4-6pm, all of the plots seem to do a similar zig-zag dance: down, then quickly up, then quickly down again.

    I’m skeptical that we’re looking some global law of nature. Looks more like some local instrumental process or data processing phenomenon.

    Looking at more data should reveal what’s really going on.
    :-|

    • … one more question, with respect to this statement: “One of the important ∆T’s in the climate system is the difference between the surface temperature and the air temperature.”

      3. How did you obtain/compute the “surface temperature”? Looking at Fig. 2, “surface temperature” appears to be measured at a depth of 1 meter.

      So, since most IR is absorbed at the surface “skin”, it would appear that readings at 1 meter would be significantly affected by wave action and other flux mixing processes (Stokes Law etc). How could this generalize into the ‘lock-step’ results you observed?

      • I meant to say ‘Navier-Stokes Law’, of course, which generalizes and characterizes flux and motion within viscous liquids. :-]

  26. Hi mr Eschenbach could it have something to do with the air humidity, at a certain point energy will be lost in evaporating mowe water to keep the humidity at a certain level, before the temp can rise again ?

    • Yes Jan I agree could the peaks and troughs be due to water vapour. early in the morning the temperature at the sea surface would warm up uninhibited until there was sufficient heat to increase evaporation and humidity then as the sun moves higher the temperature would then increase at the same time as evaporation. When both of these peak there would be the rapid drop off as intensity of the sun decreases and precipitation and cloud cover increase. In the later part of the afternoon the suns intensity reduces, the clouds disperse and there is a period where there is increased surface warming.

      Such a constant probably does have a simple answer (applying Occams Razor).

      I hasten to add my opinion here is pure conjecture from a lurker but mostly based on what Willis has said before. However does this temperature data coincide with humidity/cloud cover?

  27. The first thing that I noted was the delta T slope at sunrise (which I take is at hour six for each buoy) illustrated on Fig 3. It seems steeper at the warm end of the pacific. Is this explained (expected) due to salinity differences? Sunrise also seems graphically the max temp slope at all buoys, almost matched by the cooling slope at the end of the day. Second, it seems the cooling slope sets in before sunset (I take to be hour 18)? Is this a misinterpretation on my part of the sunrise / sunset time at each buoy location?

  28. The eight buoys located on the Equator between 165°E and 95°W have the most data covering the longest time, so I’ve looked most at those locations.

    The coldest of these eight buoys is the one at 95° W longitude, near the Americas at the far right of the map above. Average sea surface temperature (SST) there is 23.8°C (75°F). The warmest is the buoy at the other side of the Pacific at 165° East longitude. Average SST there, near the warmest part of the Pacific, is 29.2°C (85°F).

    Willis

    What is the radiative budget of the buoys located at the equator at 165°E and the radiative budget of the buoys located at 95°W?

    If it is the radiative budget that drives temperature, why is there such a big difference in temperature between the buoys on the same equatorial latitude but different longitudinal location?

    What temperature would the ocean reach at around 165° East, if evaporation did not act to cap temperature?

    • If anything the eastern buoys receive more solar radiation (less clouds). The temperature rise is due to the influx of cold water (Humboldt current) in the east which gradually warms up as it flows west.

    • trade winds—> transport of heat from east to west at the equator with ongoing warming—> warmer SST in the west tropical pacific (IPWP); in the east: upwelling (colder waters from the deep) due to this wind driven transport—> colder SST in the east tropical pacific.

  29. w ==> In your last graph — how many days of data are in the mix? Is this a long-term, consistent pattern? (is the data deltas of monthly averages by hour?) If you are using what you used in Fig 4, then yes — longer-term, repeating pattern.

    It is really quite interesting ….

    If you dig into it any more, let us know if there is some quirk in the data or if the pattern holds in different seasons etc.

  30. After reading the recent
    Willis Eschenbach’s index of articles,
    which was so long, that it exhausted me,
    there were so many subjects covered,
    I was wondering what was left
    for him to write about.

    And then he found another subject,
    and hit another home run today.

    The quality of
    the science comments
    following this article
    is another indication
    of the quality
    of the article.

    At this website
    a byline that says
    “Willis Eschenbach”
    means “must read” to me.

    Keep up the good work.
    This website would not be
    the same without all
    the Eschenbach articles!

    http://www.elOnionBloggle.Blogspot.com

  31. Very interesting. Cyclical input from sun with rapid transfer of heat to surface of ocean via direct e-m radiation, similar cyclical input to atmosphere but with a delay before the heat reaches the surface, outgoing radiation also on both direct and delayed transfers. Add up the 4 sine (approx) waves and solve for steady state but not static equilibrium. Could produce curves like that seen, probably worth investigating, mash up an electrical analogy perhaps with capacitors and resistors and a delay?

  32. It would be most interesting to see the same data for the buoys at 5 degrees north that are right under the ITCZ.

  33. Willis wrote: “This was the first surprise. The overall difference between the sea temperatures and the air temperatures was not in any order by temperature. The coolest and the warmest buoys had the widest differences between sea and air temperatures … odd.

    There could be a calibration problem between thermometers measuring SST and air temperature. If these devises were thermometers, they could be calibrated by taking readings in both water and air at different temperatures. The device measuring air temperature also measures relative humidity. So it is possible that these instruments haven’t been calibrated to produce the same reading when air and water have the same temperature. This hypothesis would explain why they record similar daily changes in temperature, but inconsistent absolute differences. Hypothesizing that calibration could be off by almost 1 degC isn’t a very attractive hypothesis. However, these devices have been exposed to the marine environment for more than a decade (?) and may have deposits on their surfaces.

    • The winds, currents and irradiate all are parallel along the equator. The starting temps vary because of cold water input on the east and warm water pileup on the west. The extremes lie at each end where the temp differences are most “out of phase” with the other inputs. Does this help define what effect temps have on the process? One might expect a balance to be reached halfway across the ocean. The 5C gradient across 11,000km is not much. It may, however, play into defining ENSO “regions”. It would be interesting to see similar data under el nino, la nina and madoku(?) situations. Similar data at 40L would be very interesting because the irradiance would remain the same along the latitude, the winds would be westerlies and more variable, the water temps would be the same (warm west-cool east), but the water would be moving longitudinally rather than latitudinally. Just might say something about the PDO, the development, strength and longevity of semi-permanent pressure systems and related jets etc. Fun article – and great discussion.

  34. Willis wrote: “I must say that I do not have any coherent explanation for the afternoon and evening peaks and troughs.”

    Nor do I. However, I’ll note that the buoys are measuring SST are 1 m below the surface of the ocean and air temperature is measured some distance above the ocean. During night time, only the top 10 um of the ocean is losing heat by evaporation and exchanging LWR photons with the atmosphere. Nighttime surface cooling doesn’t reach 1 m below the surface by conduction. It could reach a depth of 1 m by wind-driven turbulent mixing. Or it could begin when the surface cools enough to be become cooler and more dense than the water below. The rapid changes between 6:00 and 7:30 and between 16:30 and 18:30 could be associated with the end and beginning of density-driven convection in the ocean.

    Likewise, the effective heat capacities of the ocean and air could be quite different. Again, a lot depends on how fast vertical mixing is occurring in the ocean. During daytime, the air near the surface probably isn’t absorbing an appreciable amount of heat from SWR – all of the infrared wavelengths that water vapor absorbs have been depleted by absorption before SWR reaches the surface. So the air is only warmed by LWR emitted by the top 10 um of the surface of the ocean. Early morning sunlight might raise the temperature of those top 10 um of the surface (and the air immediately above) long before it raises the temperature 1 m below the surface (where some direct heating by absorption of SWR occurs when the sunlight is near vertical).

    • “Likewise, the effective heat capacities of the ocean and air could be quite different.”

      They are. Enormously different as a matter of fact.

  35. “I must say that I do not have any coherent explanation for the afternoon and evening peaks and troughs. All I can conclude from this is that all across the Equatorial Pacific, the daily temperature swings are strongly constrained by some unknown combination of natural phenomena, such that the average daily swings are identical in both timing and amplitude regardless of the average temperature of the location …”

    That’s easy. It’s the afternoon wind.

    • And exactly why would you expect “afternoon wind” out in the open ocean? Diurnal winds depend on local temperature contrasts which are largely absent at sea.

      • “Diurnal winds … are largely absent at sea.”

        Indeed, but not they are not totally absent at sea. Large temperature swings occur at coastlines with diurnal winds. But looking at this TAO buoy data temperature swings are largely absent. But they are not totally absent. It’s only .5 or .6 C.

  36. I think I have some ideas on this, Willis.
    It is called the di-urnal pattern. It has been studied for years and there is still no clear description as to what causes it. So let me try.
    There are two main layers of our atmosphere, the upper and the lower. The upper which extends into space allows the light from the sun to wrap around the inner layer. Sunlight shines through this layer, which is outside the magnetic field, becomes heated by the utra-violet portion of the light. At around 4am It begins to puff up the upper atmosphere and puts pressure on the lower atmosphere which also increases its pressure. That causes the temperature to drop.
    As the day continues this UV heating of the upper atmosphere becomes less once the magnetic field of the earth becomes the blocking force of the UV rays. The normal daily heating begins around 10:30am. And again the temperature begins to rise until 4:pm. After the sun sets, the heating all ends and the temperature drops to a low point to recycle.
    This di-urnal cycle does not require the atmosphere to move. The expanding character of the air provides all the action.
    And I must say the UV light is invisible. I have noticed that the roosters (cocks) provide a nice detector for UV first light. They start crowing between 3:45 and 4 each morning along with other wild birds.
    Lee

  37. Figure 6 has a horizontal line at 0.0 and a vertical at 12AM that intersect at the center of the figure.
    I would like to see 2 days of data running… first day standard…second day with a shade that blocks
    direct and reflected sunlight from reaching the buoy.

  38. On Figure 4, I would expect to see a parabolic shape between 6hrs and 18hrs through the daylight cycle if there were no dampening due to cloud cover etc between 9hrs and 15hrs. The brief uplift from 18hrs and also between ~3hrs and 6hrs are fascinating, both stronger in the west. A very interesting post, thanks.

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