Ozone Hole Splits in Two

DaDigz writes "CNN is reporting here that the hole in the ozone layer above Antarctica has split in two "like a giant amoeba". It's not yet been determined whether this is a result of unusual weather patterns or whether the ozone layer is recovering. One can hope, though, that this may be a sign of a mend in the ozone layer."

Comments

I'm just curious..

[hitzroth]

do we know for sure that there was a time when there wasn't a hole in the ozone layer over Antarctica?

the 80s strike back

[chenzhen]

An interesting factor that is often ignored is the time it takes CFCs to ascend to the upper atmosphere. Most of those produced during the world's peak output have not even made it to the point where they would do any damage yet. To generalize, it may be healing now, but in the next ten years the sum total of the industrial 1980's may rip the scab right off.
P

had to happen

[infonography]

it's a simple example of The Coriolis Force

The hole is in a cloud layer, it's not a object. Winds and gravity will mix the ozone back into the hole, making the overall layer thinner but still there.

http://www.windpower.dk/tour/wres/coriolis.htm

I wonder if the hole is something that is recurring rather then just an effect of pollution. maybe gravity thickens the layer around the equator leaving open patches at the poles. But it's safer to not be so messy with the planet.

Waves and the Polar Vortex

[jellisky]

'Twas a very interesting evolution of the "hole", I must admit. Looks like a good fluid dynamics experiment gone unstable to me.

A quick summary of why the ozone hole exists:

- During polar winters, the solar insolation (amount of light from the sun) goes to zero. Since the photochemical reaction by ozone on UV light is no longer there, the stratosphere begins to cool around the poles. This leads to no ozone being produced or destroyed. (Ozone, in the stratosphere, requires light to be created in the first place.)

- This cooling leads to the formation of a very strong vortex by an atmospheric "law" called thermal wind. This vortex tends to be incredibly strong, usually on the order of 50 m/s (112 mph). This vortex usually covers the entire polar region.

- Given the strength of this vortex, very little mixing occurs between contents inside the vortex and outside the vortex. So, as time progresses, the already present chlorine and flourine compounds in the vortex have time to react with the ozone and deplete it noticably (since the vortex doesn't allow the ozone from the lit-up areas of the globe to mix in and refresh the levels).

- As the sun comes back up in polar spring, the photochemical reactions begin again, further reducing the levels of ozone. However, these reactions warm up the middle of the vortex. This warming tends to break down the vortex quite quickly and allows the ozone from the middle latitudes mix in and refresh the ozone levels.

Now, all this happens in both hemispheres during the appropriate winter months. But the Antarctic hole tends to be stronger than the Arctic one for one very simple reason: land. Topography helps set up large-scale waves in the atmosphere's flow. These waves can influence the polar vortex by essentially perturbing it. These perturbations can then grow (depending on the properties of the vortex) and become unstable, leading to a total vortex breakdown. Those events are commonly seen in the Arctic vortex since there are three large mountain ranges in the Northern Hemisphere to excite planetary-scale waves. But around Antarctica, there aren't any significant mountain ranges to excite these waves, so the vortex tends not to be perturbed significantly.

But, it appears this season, that something is causing a very strong wavenumber-2 perturbation (wavenumber-n perturbations have n crests and troughs around a latitude circle). That's pretty obvious from the elliptical early evolution and, then, the eventual breakdown into two lobes. What actually "caused" this amplification is an excellent question. Perhaps this year's vortex was inherrently unstable to wavenumber-2 perturbations? Perhaps this season's El Nino had some odd effect on it? (Doubt that, but it's an interesting idea.) Either way, this event will be studied quite heavily the next few years, I'm sure. (Perhaps even by myself at some point.)

-Jellisky

Re:Possibly a mend? Really?

[Mr. Slippery]

However, engineering solutions should not be wholly discounted.

As a temporary stopgap as we move to sustainable energy, perhaps they may be of use. They're certainly interesting to think about.

However, until we have a much deeper understanding of ecology I'd have to say it's much wiser to give priority to stopping our f*cking around with the spaceship's life support system and letting it reset itself, than to f*cking with it some more in hopes of balancing out our first f*ckups.

However, interest in organic farming has increased greatly recently, and organic farming uses much more land per pound of food grown than conventional high-yield farming.

The difference is not that great, perhaps on the order of 10 percent. (Some say that there's no significant difference at all. There are others who claim that organic methods have very low yields, but I think agriculture research sponsored by Dow and Monsanto has about the same credibility as lung cancer research sponsored by Phillip Morris.) Considering that most organic farmers are new to the methods involved, we can expect yields to rise as experience is gained.

Also, if you want to talk land use you need to factor in the land used for energy production, the land taken up by chemical plants, the land used up by drilling and mining operations, the land used for waste disposal of all of these operations, and the land eventually rendered unsuitable for agriculture by non-sustainable methods.

That's not even factoring in water pollution from fertilizer and pesticide production and runoff, air pollution from chemical production and energy production. And not even touching on the health costs of pesticide contamination in the finished food product.

Considering the total resource footprint, organic is the clear winner.

And there's little "conventional" about chemical-saturated high-yield farming - it represents a very small slice of humanity's experience with agriculture.

The secondary (and tertiary, etc.) effects of plans such as the Kyoto Protocol are myriad and difficult to predict (or even attribute after the fact).

Certainly no more so than the effects of continuing to mess around with the environment as we are.