Susan Solomon et al: Decreases in Tropical Stratospheric Ozone

Posted: December 4, 2012 by tallbloke in atmosphere, cosmic rays, Cycles, Ocean dynamics, ozone, Solar physics, solar system dynamics

This is interesting. Reductions in the temperature of the lower stratosphere have hitherto been assumed to be a result of the ‘thickening’ of the troposphere by the increase in carbon dioxide, leading to increased absorption of surface emitted long-wave radiation and thus ‘global warming’. Now Susan Solomon, IPCC lead author seems to be introducing strong uncertainty into the issue. Extreme Ultra Violet light from the Sun is known to destroy ozone. EUV was at a long term peak while the Sun was highly active in the late C20th. This appears to raise the possibility that as well as being at least partly (possibly mainly) responsible for the ‘ozone hole’ which developed over the poles, more of the incoming solar radiation was reaching the surface due to this effect, thus contributing to late C20th warming.

Uncertainties in the evolution of stratospheric ozone and implications for recent temperature changes in the tropical lower stratosphere

Journal publication date 14/09/2012
Journal Geophysical Research Letters
Volume 39
Number of pages 4
Original language English

Abstract

Observations from satellites and balloons suggest that ozone abundances have decreased in the tropical lower stratosphere since the late 1970s, but this long-term change is occurring in a region of large interannual variability.
Three different ozone databases provide regression fits to the ozone observations, and are available for use in model studies of the influence of ozone changes on stratospheric and tropospheric temperatures. Differences between these ozone databases suggest that the estimated decreases of tropical lower stratospheric ozone in recent decades are uncertain by about a factor of two to three. The uncertainties in ozone decreases lead to similar uncertainties in cooling of the tropical lower stratosphere, a key area of focus in climate change studies.
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I’ll add more detail from the paper later.

Comments
  1. Stephen Wilde says:

    Interesting progress.

    Since 2000 there is evidence that ozone has been increasing again at least in the region above 45km.

    Stratospheric temperatures are as important for climate zone positioning as tropospheric temperatures because a cooling stratosphere will allow the tropopause to rise without any need for warming of the troposphere to occur first.

    Hence the room for a top down solar effect as well as a bottom up oceanic effect.

    It would be amusing to me if it turns out that the temperature of the stratosphere together with ozone amounts really are both controlled primarily by solar variations.

    For my purposes though I would need to see the effects above both tropics and poles because I need a stronger effect at the poles relative to the equator in order to shift the climate zones in the right direction.

    If ozone decreases more at the poles than above the equator then that pattern of stratospheric cooling would result in a poleward shift in the climate zones because the tropopause height would rise more at the poles than at the equator thereby allowing the jets and climate zones to slide poleward.

    Of course it is all relative due to the large difference in the depth of the atmosphere between equator and poles so that the same proportionate change in ozone amounts could have different results above equator and poles.

    Still, progress is being made.

  2. Doug Proctor says:

    Stephen Wilde says: December 4, 2012 at 10:25 am

    …. a cooling stratosphere will allow the tropopause to rise without any need for warming of the troposphere to occur first.

    Like all things, air rises or falls because of density differences, not temperatures.

    Unless relative density changes within the stratosphere happens, the relative positions of air masses within the stratosphere won’t change. Unless the density of the stratosphere at the stratosphere/troposphere boundary changes, there won’t be any movement of the boundary.

    IIf the stratosphere loses mass, then the boundary will rise. If the upper tropospheric boundary does not increase in bouyancy force relative to the downward gravitational force of the stratosphere, the boundary again won’t change.

    If the boundary is determined by other elements, there could be a push-back effect on the boundary, so that the net change is less than the initial.

    TBS, I don’t understand how a cooler stratosphere would cause the troposphere to rise by itself.

  3. michael hart says:

    “It would be amusing to me if it turns out that the temperature of the stratosphere together with ozone amounts really are both controlled primarily by solar variations.”

    Indeed, Stephen. Regarding the ozone story, I suspect nature still has a few tricks left up it’s sleeve that may embarrass some of the modellers. DeWitt Payne and others have some opinions about ozone at blogs such as The Science of Doom that I keep meaning to go back and read.

    Something I haven’t yet read about is how large polar variations in albedo impinge on ozone-effects because it may be a significant source of UV that comes from the base of the atmosphere, not the top. Not saying that aspect is necessarily important, but the thought intrigues me and I’ve not read about it.

  4. Stephen Wilde says:

    Doug Proctor see here:

    “Suppose, for example, that the surface temperature and the tropospheric
    temperature gradient are given and that the temperature of the stratosphere
    varies. Then, a cold stratosphere will be associated with a high tropopause (low
    tropopause pressure), and a warm stratosphere will correspond to a low
    tropopause (high tropopause pressure).”
    from here page 14:

    pdf here

  5. Stephen Wilde says:

    Hmmm. Looks like the link is broken but you’ve got the relevant extract [was --Tim]

  6. tallbloke says:

    WordPress screws up hyphenated URL’s, use tinyurl.com to make a shortlink. try this:

    http://tinyurl.com/cqlzd4v

  7. p.g.sharrow says:

    Hi Stephen; if I remember correctly, Stratospheric temperatures and Ozone rise and fall together as energy is needed to radicalize O2 to create O3 and a decrease in energy will allow O3 to break down to O2. At least that was the science before the Eco-nuts decided to save the world from Ozone hole disaster by outlawing chlorinated hydrocarbons. Then the accepted science was changed to declared that Freon somehow got up into the high Stratosphere and destroyed the Ozone.
    I would think that a shrinking atmosphere due to reduced energy would not cause the stratosphere to warm over all, but it could change the temperature measured at a particular elevation as the elevations of the water cycle changes. pg

  8. michael hart says:

    Speculating, I wonder precisely how much uncertainty in tropical ozone the IPCC might like? And how much do they need before they could conclude, in true “worse-than-we-thought” fashion, that anthropogenic ozone-depletion is the cause of the famous non-appearance of the tropospheric hot-spot predicted by IPCC models?

    The ghost of Ockham is sharpening his razor.

  9. Stephen Wilde says:

    pg.

    I think less ozone means cooler and more ozone means warmer but the ozone quantity responses to solar variations are apparently not of the same sign below and above 45 km.

    Water vapour might have an effect at the tropopause but not at 45km.