Relationship Of Sea Level And Lower Troposphere Temperature Along The Equator

Along the equator, sea surface height and lower troposphere temperature track each other very closely

ScreenHunter_4003 Oct. 25 01.01

At the blue circle we see almost perfect correlation between changes in lower troposphere temperature and changes in sea surface height (see graph below.) Note that neither shows any net change since 1992.

ScreenHunter_4002 Oct. 25 00.58

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15 Responses to Relationship Of Sea Level And Lower Troposphere Temperature Along The Equator

  1. KTM says:

    Yet some believe that CO2 alone is the master control knob of the earth’s climate…

  2. Brian G Valentine says:

    I suppose that would be expected, since equatorial insolation is virtually constant throughout the year. Certainly don’t see any global warming going on there, and if it isn’t seen there, it isn’t going to be seen.

  3. As temps go up the air rises and the resulting low pressure allows the sea level to rise? Just guessing.

    • David A says:

      Consider that the local ocean waters expand due to insolation and warmer then average water also coming to and near the surface.

    • Robert B says:

      The sea level is out of phase a little to the west? Is that blue negative values of the anomaly?

      Scientists find that global warming makes the sea lumpier?

    • Robert B says:

      Just to clarify – Ocean currents should affect the surface temperatures but this strong correlation is not realistic. I would be surprised if there was such a good correlation with a region of the lower troposphere that warms when the currents are favorable, but the whole globe?

  4. This sea-level bulge has nothing to do with solar heating of the near-surface water … and while there is apparently a causal link between variations in the bulge and variations in local air temperature, the link is not of the nature that Morgan is thinking. Variations in the bulge would be associated with variations in thermal energy transport from below to the surface, which would be expected to cause forcing in the air temperature.

    The phenomenon is a type of standing wave.

    This is caused by a combination of 1) upwelling along the eastern Pacific portion of the equator and 2) converging surface currents of the Northern Pacific and Southern Pacific gyres. Both of these are driven primarily by terrestrial rotation.

    Vertical circulation in the ocean is the opposite of what it is in the atmosphere. Upwelling water is colder water. Downwelling water is warmer water.

    The correlation with local temperature is most likely because when upwelling water increases in temperature over what is typical for that location, this is because of an increase in the rotation-forced net transport of thermal energy from the depths to the surface. This increased surface temperature would be expected to force a rise in atmospheric temperature as it takes some time for the atmosphere to transfer the new energy to space or to another region of the atmosphere.

    The effect of air pressure on all of this is going to be comparatively small. Consider that at any given time, the equatorial surface temperature over the ocean is not going to vary greatly from one part of the equator to the other. But we see on the map a dramatic change in sea level as one moves west along the Pacific equator. The effect tapers off slowly as the easterly surface current carries the water away from the location of the upwelling. That pattern is consistent, regardless of temperature. This is powerful evidence of a standing wave existing near, and at, the surface.

    RTF

  5. daveburton says:

    This is very interesting Tony!

    Is this a unique case? I.e., does this relationship hold only in the eastern equatorial Pacific, or is there such a relationship elsewhere, too?

    If this correlation holds only in that one location, then it might well just be a coincidence, and unimportant.

    But if the correlation holds along much of the equator, then I think this is a very important observation, Tony, and you should publish a paper about it. I think it has some important implications:

    1. I would guess that averaged/smoothed RSS is probably strongly correlated with sea surface temperature. If so, then sea surface height, as measured by satellite altimetry, must be reflecting thermal expansion and contraction of the upper ocean.

    2. That would suggest that satellite altimetry is not completely unreliable (though tide gauges are still obviously better).

    3. It would also suggest an explanation for the difference between tide-gauge and satellite measurements of sea-level rise: Namely, that the reason satellites measure more sea-level rise than averaged tide-gauges is that the upper layer of the ocean is warming a bit. Thermal expansion in the upper layer of the ocean affects satellite altimetry measurements of the level or the open ocean, but has little or no effect (depending on where it occurs) on coastal sea-level (measured by satellites).

    What are the data sources, Tony?

    • The data is RSS TLT and University of Colorado sea surface heights. I will look around at other locations, but along the eastern Pacific the behavior is very constant.

      • Gentlemen, the warmest part of a gyre is the spot where the current turns away from the Equator to begin its swing toward the poles. This bulge is not caused by SSTs. Even if you also find it in the Eastern Atlantic, it is still caused by the rotation factors that I indicated — upwelling, and converging currents. The upwelling is cold water, not warm.

        • daveburton says:

          I don’t understand, Richard.

          1. What gyre? We’re talking about the equator. There’s no cyclone activity at the equator (except on the cover of Al Gore’s goofy book), because there’s no Coriolis Effect there.

          2. How do rotational factors explain the correlation between RSS temperatures and SSH?

          You wrote, “The correlation [of SSH] with local temperature is most likely because when upwelling water increases in temperature over what is typical for that location, this is because of an increase in the rotation-forced net transport of thermal energy from the depths to the surface.”

          But that doesn’t make sense to me.

          1. Deep water temperature at any given location is very, very constant. So what would cause upwelling water to increase in temperature over what is typical for that location, other than a decrease in rate of thermocline circulation? Is that what you think is fluctuating (as seen in Tony’s graph), the rate at which the water is upwelling?

          2. There’s no “net transport of thermal energy from the depths to the surface” at the equator. Or, rather, it’s negative. The deep water is very cold, and the surface water is quite warm. Thermocline circulation drives some of that cold water up toward the surface, but that makes the surface colder, not warmer.

          3. What do you think causes sea surface height to sometimes increase (at the peaks in Tony’s graph), and sometimes decrease (at the troughs in Tony’s graph), if it isn’t water temperature and/or air pressure?

        • I’ll try to answer your questions, but the answers are not necessarily simple.

          First of all, a gyre is not a cyclone. They are two completely different things.

          Second. Most gyres are the size of half an ocean. They absolutely do extend to the Equator.

          Third. The predominant cause of lateral currents in the ocean is terrestrial rotation. A little arithmetic should be sufficient for you to realize the amount of power involved in pushing half an ocean around in a circle at the prevailing speeds.

          Fourth. There is also the matter of upwelling water, which is also driven by rotation.

          Fifth. You say there is no Coriolis effect at the Equator. Well, yes and no. What there is, most of all, is slippage in the ocean as the Earth rotates. This effect is actually strongest at the Equator, and weakest at the most poleward parts of an ocean. At the North Pole, it is zero. At the Equator, it is massive, the highest amount of slippage of any latitude. So there is a massive rotational force that results from this. If anyone tells you otherwise, they are incompetent or they haven’t thought about it. Some of this is Coriolis effect, and some of it is just the effect of the continents forcing the water to change direction. Now when talking about a tropical cyclone, you have a much smaller area involved. The difference in relative velocity between the north and south ends of the cyclone is miniscule at the Equator, which is why you may not observe a Coriolis effect there. But technically, as long as the entire system is on one side of the Equator, there is an effect.

          Sixth. Another rotational aspect of this is the Trade Winds, which are driven primarily by rotation through the same means as the ocean currents, i.e. slippage. These Trade Winds gain a north-south bent from the Coriolis effect, which causes them to converge near the Equator, further mashing the water together between them, and also the E-W movement pushes the water offshore from western South America at the Equator, which further promotes upwelling of cold water.

          Seventh. We’re not talking about “deep” water but intermediate, as I had stated, which carries huge amounts of heat that is transported down from the surface, and then back up again, and these intermediate waters can fluctuate rather dramatically in temperature from one year to the next.

          Eighth. Yes, I’m sure that the rate of upwelling varies from year to year, because we’re talking about a very large standing wave, and it’s going to have fluctuations due to oscillation of the various forcings.

          Ninth. Your point number 2. There is massive transport of energy into and out of the oceans, at opposite ends of vertical convection currents. Sometimes this is relatively stable in terms of the balance between input and output. Sometimes it is not. When it is not, there can be net transport from ocean to air. Now when you write “[. . .] that makes the surface colder, not warmer”, you are misunderstanding me. What you wrote was actually my point, which makes you unequivocally wrong about SSTs creating the bulge. But look at it this way: constant rate of absorption by the ocean in an upwelling area = no change to surface air temperature. Decreasing rate of absorption, all else being equal, equals increasing surface air temperature, which will also warm the troposphere because there’s a lag as the troposphere finds somewhere else to put the excess energy. Increasing rate of absorption, all else being equal, means the opposite: decreasing air temperature. So that is how I explain the correlation between the local SL and temps.

          I think I have answered all of your questions to the best of my ability. If there’s anything else, or something I neglected, please don’t hesitate.

          RTF

        • Oh, something I missed. Ten. I do think that air pressure is a factor, and I said so. But as I said, it is “comparatively small” next to the effects of the vertical and lateral currents we’re discussing.

          RTF

  6. Thomas T.S.Watson says:

    While I see the topic you are both encountering, I suggest that you consider the overall affects of the Moon. The Moon’s Face to Earth has a Positive Magnetic outlook and i strongly suggest that these magnetic forces, determine the high tidal effects of the Northern Hemisphere and the temperature you speak of is the true effect of the completed phases of our Moon during a “Full Moon” twelve month cycle. To me, this is the determination of the High dips there are in the graph.
    My book Climate Change Explained by Magnetism? ISBN9780646477220 is available as a CD(pdf) @ $45.00in postage and handling, so this is all new technology and should be carefully considered in every aspect of your understanding and reasoning..
    To me you are finding answers that have another reason for their respective cause. It is like the cause of Climate Change being associated to the Carbon Dioxide that has absolutely nothing to do with changing the orbital position of Earth within the Sun’s Heliosphere, and changing the atmosphere of Earth, Yes!, the seasons are changing this overall affect, and the Earth’s attitude within these changed Heliosphere conditions, are initiated during these natural cycles from our Sun..

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