Saturday, September 21, 2013

New paper attempts to explain why global warming caused cooling of the sub-Arctic during the 20th century

A paper published today in Theoretical and Applied Climatology notes, "the subarctic Atlantic sea surface temperature (SST) has been cooling during the twentieth century." The authors investigate this perplexing observation with climate model "experiments." [Note climate science is the only field that considers computer programming tweaks to be scientific "experiments"]

According to the authors, "In the most of models, the longwave radiation [from greenhouse gases]... exert a warming effect, and the shortwave radiation [from the Sun] exerts a cooling effect." However, it appears the models have the basic physics backwards, because longwave radiation from greenhouse gases cannot penetrate the sea surface and thus only causes evaporative cooling of the ocean 'skin' surface, whereas 
shortwave radiation from the Sun can penetrate to depths of up to 100 meters to cause bulk ocean warming. 

Theoretical and Applied Climatology October 2013, Volume 114, Issue 1-2, pp 9-19


Abstract

Various ocean reanalysis data reveal that the subarctic Atlantic sea surface temperature (SST) has been cooling during the twentieth century. A similar cooling pattern is found in the doubling CO2 experiment obtained from the CMIP3 (coupled model intercomparison project third phase) compared to the pre-industrial experiment. Here, in order to investigate the main driver of this cooling, we perform the heat budget analysis on the subarctic Atlantic upper ocean temperature. The net surface heat flux associated with the increased concentration of greenhouse gases heats the subarctic ocean surface. In the most of models, the longwave radiation [from greenhouse gases], latent heat flux, and sensible heat flux exert a warming effect, and the shortwave radiation exerts a cooling effect. On the other hand, the thermal advection by the meridional current reduces the subarctic upper ocean temperature in all models. This cold advection is attributed to the weakening of the meridional overturning circulation, which is related to the reduction in the ocean surface density. In particular, greater warming of the surface air than of the sea surface results in the reduction of surface evaporation and thereby enhanced freshening of the ocean surface water, while precipitation change was smaller than evaporation change. The thermal advections by both the wind-driven Ekman current and the density-driven geostrophic current contribute to cooling in most of the models, where the heat transport by the geostrophic current tends to be larger than that by the Ekman current.


Related: There is also a negative feedback phenomenon on CO2 levels discussed in a paper published in Nature which shows that the evaporative cooling of the ocean 'skin' from increased downwelling longwave radiation allows increased uptake of CO2 due to increased solubility of CO2 at lower temperatures.

4 comments:

  1. I went into this supposed ocean skin effect in considerable detail some time ago, see here:

    http://www.newclimatemodel.com/must-read-greenhouse-gases-can-cause-cooling/

    "it seems most likely that the net global effect of more greenhouse gases is actually a miniscule cooling rather than a miniscule warming.

    Still nothing to worry about though."

    I am not aware of any ewidence that the temperature gradient up through the ocean skin does actually decline when downward longwave increases.

    If it does create more evaporation (as it must) then the gradient is more likely to increase due to the well known net cooling effect of evaporation.

    The ability of solar shortwave to get past the ocean skin is the reason why changes in global cloudiness are by far the main cause of climate changes because that alters the proportion of incoming solar energy that is able to enter the oceans to fuel the climate system.

    Stephen Wilde

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  2. "the subarctic Atlantic sea surface temperature (SST) has been cooling”.
    The science is as good as the grammar.
    Also
    “the shortwave radiation [from the Sun] exerts a cooling effect."
    Those creators of comic book super-heroes knew something then.
    http://www.comicvine.com/bizarro/4005-8312/
    Bizarro’s eyes emit freeze rays as opposed to Superman's heat vision

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  3. I know German puts the verb at the end and I think Korean does also, so maybe they mixed up the wording in translation. They could not lack any understanding could they? In coming short wave radiation leading to cooling ? Surely, that must be a translation problem? Surely ????

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    Replies
    1. don't think so since the latent heat flux and sensible heat flux are in the same sentence and also exert a warming effect

      doesn't surprise me at all - the models are based on very poorly documented old FORTRAN code that can't even model convection properly or handle rounding errors

      http://hockeyschtick.blogspot.com/2013/07/new-paper-finds-same-climate-model.html

      http://hockeyschtick.blogspot.com/2013/09/new-paper-finds-ipcc-climate-models.html

      Delete

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