Global Microwave Sea Surface Temperature Update for March, 2013: -0.01 deg. C

April 2nd, 2013 by Roy W. Spencer, Ph. D.

The satellite-based microwave global average sea surface temperature (SST) update for March 2013 is -0.01 deg. C, relative to the 2003-2006 average (click for large version):

The anomalies are computed relative to only 2003-2006 because those years were relatively free of El Nino and La Nina activity, which if included would cause temperature anomaly artifacts in other years. Thus, these anomalies cannot be directly compared to, say, the Reynolds anomalies which extend back to the early 1980s. Nevertheless, they should be useful for monitoring signs of recent ocean surface warming, which appears to have stalled since at least the early 2000’s. (For those who also track our lower tropospheric temperature [“LT”] anomalies, these SST anomalies average about 0.20 deg. C cooler since mid-2002).

The SST retrievals come from Remote Sensing Systems (RSS), and are based upon passive microwave observations of the ocean surface from AMSR-E on NASA’s Aqua satellite, the TRMM satellite Microwave Imager (TMI), and WindSat. While TMI has operated continuously through the time period (but only over the tropics and subtropics), AMSR-E stopped nominal operation in October 2011, after which Remote Sensing Systems patched in SST data from WindSat. The various satellite datasets have been carefully intercalibrated by RSS.

Despite the relatively short period of record, I consider this dataset to be the most accurate depiction of SST variability over the last 10+ years due to these instruments’ relative insensitivity to contamination by clouds and aerosols at 6.9 GHz and 10.7 GHz.

14 Responses to “Global Microwave Sea Surface Temperature Update for March, 2013: -0.01 deg. C”

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  1. Norman says:

    My question would be, if the sea surface temperature is flat since the early 2000’s, where is the energy coming from to heat the ocean down to 700 meters? Solar energy does not penetrate that far down and why would it only heat water below the surface and not above? If the sea surface is not warming then ocean currents would not be able to warm the water below since they are not gaining excess energy. Where is the energy coming from to heat the lower layers of ocean?

  2. Denis Rushworth says:

    Dear Dr. Spencer,

    Sea surface temperature has been flat for a decade but sea levels continue a slow rise. Is it all surface ice melt water, or could there be something wrong with either your numbers, or the sea surface numbers?

  3. Norman says:

    Denis Rushworth

    Denis, some researchers attribute irrigation of fossil water (deep underground aquifiers that replenish very slowly and will contribute to the above ground water levels), up to 25% of sea level rise and irrigation is growing in amount. The researchers do say it is very difficult to get a precise measure of how much irrigation may actually contribute to the sea level rise. Lot of debate on this issue.

  4. Norman says:


    I have thought the same thing in the past but I think the energry release from volcanoes is far to low to explain the increase in deep water temp. The energy amount is fairly large.

    • Ray says:

      Do we really know how much heat is transferred from the total ocean floor (not just volcanoes), to that degree of accuracy?

      • John says:


        Good question? There are many geological sea floor vents that release methane, sulfur and other gas compounds in addition to volcanoes. Methane hydrates are found throughout the ocean floor often close to faults and vents in the sea floor not just around large undersea volcanoes. Norman claims that undersea volcanoes cannot account for all the additional down to 700 meters. He may very well be correct, but the earth is much more permeable than just a few large volcanoes may suggest.

        • John says:

          My post above should have read: “Norman claims that undersea volcanoes cannot account for all the additional heat down to 700 meters.”

    • Mike Flynn says:


      Nobody knows how much energy is emitted by undersea vents.
      Nobody knows how many vents there are.

      The abyssal depths sit quite close to the 99+ percent of the Earth that is still incandescent.

      I think that anybody who claims to know the quantum of heat flow into the waters resting on the mostly incandescent Earth is either a genius, a fool, or a fraud – in the broad sense. I intend no offence to the genius or the fool.

      Lord Kelvin calculated the age of the Earth by extrapolating measured heat loss, but was wildly incorrect. He “foolishly” ignored radioactive energy generation. He assumed that his knowledge was greater than it was, and his obvious genius did not prevent him from reaching an incorrect answer.

      Kelvin held to his views, and became even more dogmatic in the face of mounting evidence that he was wrong. It is interesting to note that he and his supporters adopted much the same approach as some “climatologists” today. “The science is settled” sort of thing.

      I think he was foolish to cling to a wrong assumption for the rest of his life, and apparently used his position to browbeat his opponents, rather than dispassionately look at facts.

      I think there may be present day parallels – but who knows?

      In the meantime,

      Live well and prosper.

      Mike Flynn.

  5. Norman says:

    Upon further research it seems possible that the volcanoes could be a source of the heat.

    It would be the more logical source since the surface is not adding the heat and the heat has been experimentally (diving buoys with actual measurements) verified.

    I guess the logic would be that if the surface is not causing the warming yet the warming is real, there has to be a source and volcanoes are there and may have become much more active in the last few years.

    Maybe not the best source but it seems some people are looking into it.

    Anyway thanks for the direction, it may help explain the observations.

  6. nigel says:

    What Mike Flynn says about Lord Kelvin is accurate enough.
    However, to be fair, Kelvin was virtually a fossil himself
    by the time radioactivity was discovered; and a clinching reason for a long-lived as opposed to a short-lived sun (which was part of his argument)was not discovered until thirty years later.

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