• Perhaps this has been discussed, but I have not seen a detailed explanation of the Ozone Layer setting.
    It's puzzling to me because it does not show any Antarctic ozone depletions, but does show several signficant depletion areas (< 250 DU) around Hong Kong, Baja California and the Bahamas.
    Your info page says it is "column ozone", which implies the total ozone between the top of the atmosphere down to the troposphere. But it looks more like tropospheric ozone "pollution" to me.

    What are we looking at and where does it come from?


  • Sailor Moderator

    Data for the ozone layer are provided by ECMWF.


    See document to download:

    To see the shape of the ozone hole above polar region, it should be better to have a polar projection map. The Mercator projection is obviously not suitable for high latitudes.
    Or a 3D rendering.

  • The issue is not with the forecast data source which is being displayed fully, even within the 2D Windy plot all the way to 90 degrees south. The 'hole' or depletion area appears and disappears seasonally. The depletion begins to occur at the beginning of the southern hemisphere's Winter onset in June, and reaches its peak just after Winter finishes in September, but the depletion is completely gone again by the first month of Summer in December.

    The southern summer finished last week so right now there's no ozone 'hole' depletion area present to see. Give it 4 to 5 months.

    If the ozone displayed was from tropospheric pollution sources only, then China would stick-out like a very sore thumb, but as you can see it isn't even registering as a source (such is the tiny scale of contribution of human created ozone). This is because the global production and destruction is controlled by natural-variation of earth's rotation angle with respect to the sun, and the resulting annual change of seasons.

    "... The atmospheric lifetime of tropospheric ozone [which includes photo-chemical smog pollution] is about 22 days; its main removal mechanisms are being deposited to the ground, the above-mentioned reaction giving HO•, and by reactions with OH and the peroxy radical HO2•. ...'


    Screenshot_2019-03-06 Windy as forecasted.png
    Screenshot_2019-03-06 Windy as forecasted(2).png
    Screenshot_2019-03-06 Windy as forecasted(1).png

    The non-depleted ozone forecast level shown above, is currently about double that of a typical early-Spring depletion level during the past decade:
    Source: https://en.wikipedia.org/wiki/Ozone_depletion

  • "Data for the Ozone Layer are provided by ECMWF"

    @idefix37 and @WXcycles
    Thanks for the info, especially the ECMWF modelling issues slides and the seasonal aspect of the ozone layer.

    So the Antarctic ozone depletion cycles are driven by the Southern polar vortex, which is now over for the season, meaning that the holes should reappear later this year.

    Do the ozone forecasts tend to correlate to the UV forecasts (as theory would suggest)? Right now I don't see any correlation.

  • @af4ex

    The two links in my reply describe it in detail. The partial 'hole' (thinning, not a hole) is largely over an area that's uninhabited by humans. Plus the angle of incidence of the Sun in Spring means that rays still have to pass through plenty of Stratospheric Ozone to get to the surface. And by early Summer when the incident rays are getting higher, the hole has already closed. So it's not much of a hazard in practice.

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