Posted on 10/05/2007 7:35:25 PM PDT by blam
European Space Agency
Date: October 4, 2007
2007 Ozone Hole 'Smaller Than Usual'
Science Daily — The ozone hole over Antarctica has shrunk 30 percent as compared to last year's record size. According to measurements made by ESA’s Envisat satellite, this year’s ozone loss peaked at 27.7 million tonnes, compared to the 2006 record ozone loss of 40 million tonnes.
Ozone hole over Antarctica measured in September 2007 by Envisat. The ozone loss in 2007 peaked at 27.7 million tonnes, compared to the 2006 record ozone loss of 40 million tonnes. (Credit: KNMI - ESA)
Ozone loss is derived by measuring the area and the depth of the ozone hole. The area of this year’s ozone hole – where the ozone measures less than 220 Dobson Units – is 24.7 million sq km, roughly the size of North America, and the minimum value of the ozone layer is around 120 Dobson Units.
A Dobson Unit is a unit of measurement that describes the thickness of the ozone layer in a column directly above the location being measured. For instance, if an ozone column of 300 Dobson Units is compressed to 0º C and 1 atmosphere (the pressure at the Earth’s surface) and spread out evenly over the area, it would form a slab of ozone approximately 3mm thick.
Scientists say this year’s smaller hole – a thinning in the ozone layer over the South Pole – is due to natural variations in temperature and atmospheric dynamics (illustrated in the time series to the right) and is not indicative of a long-term trend.
"Although the hole is somewhat smaller than usual, we cannot conclude from this that the ozone layer is recovering already,” Ronald van der A, a senior project scientist at Royal Dutch Meteorological Institute (KNMI), said.
"This year's ozone hole was less centred on the South Pole as in other years, which allowed it to mix with warmer air, reducing the growth of the hole because ozone is depleted at temperatures less than -78 degrees Celsius."
During the southern hemisphere winter, the atmospheric mass above the Antarctic continent is kept cut off from exchanges with mid-latitude air by prevailing winds known as the polar vortex. This leads to very low temperatures, and in the cold and continuous darkness of this season, polar stratospheric clouds are formed that contain chlorine.
As the polar spring arrives, the combination of returning sunlight and the presence of polar stratospheric clouds leads to splitting of chlorine compounds into highly ozone-reactive radicals that break ozone down into individual oxygen molecules. A single molecule of chlorine has the potential to break down thousands of molecules of ozone.
The ozone hole, first recognised in 1985, typically persists until November or December, when the winds surrounding the South Pole (polar vortex) weaken, and ozone-poor air inside the vortex is mixed with ozone-rich air outside it.
KNMI uses data from Envisat's Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) instrument to generate daily global ozone analyses and nine-day ozone forecasts.
Ozone is a protective layer found about 25 km above us mostly in the stratospheric stratum of the atmosphere that acts as a sunlight filter shielding life on Earth from harmful ultraviolet rays. Over the last decade the ozone layer has thinned by about 0.3% per year on a global scale, increasing the risk of skin cancer, cataracts and harm to marine life.
The thinning of the ozone is caused by the presence of ozone destructing gases in the atmosphere such as chlorine and bromine, originating from man-made products like chlorofluorocarbons (CFCs), which have still not vanished from the air but are on the decline as they are banned under the Montreal Protocol, which was signed on 16 September 1987.
Envisat can localise ozone depletion and track its changes, enabling the rapid estimation of UV radiation as well as providing forecasting. The three atmospheric instruments aboard Envisat are SCIAMACHY, the global ozone monitoring by occultation of stars (GOMOS) sensor and the Michelson interferometer for passive atmospheric sounding (MIPAS).
ESA data form the basis of an operational near-real time ozone monitoring and forecasting service forming part of the PROMOTE (PROtocol MOniToring for the GMES (Global Monitoring for Environment and Security) Service Element) consortium, made up of more than 30 partners from 11 countries, including KNMI.
As part of the PROMOTE and TEMIS service, the satellite results are combined with meteorological data and wind field models so that robust ozone and UV index forecasts can be made.
GMES responds to Europe’s needs for geo-spatial information services by bringing together the capacity of Europe to collect and manage data and information on the environment and civil security, for the benefit of European citizens.
The GMES Service Element (GSE) has been preparing user organisations in Europe and worldwide for GMES by enabling them to receive and evaluate information services derived from existing Earth Observation satellites since 2002.
Note: This story has been adapted from material provided by European Space Agency
So what amount of annual loss is considered to result in stasis?
We are entering the beginning of the 11 year sunspot cycle. This signals an increase in solar activity including solar flares and sunspots. These solar events create ozone.
well, d’oh!
The ozone hole is shrinking! We’re doomed!
(Wait, is the ozone hole good or bad?)
If they are, it's not because of ozone depletion.
For a short period each year, the edge of the ozone hole passes
over Tierra del Fuego, at the southern end of the South American
continent. This has led to a flurry of reports of medical damage
to humans and livestock. Dermatologists claim that they are seeing
more patients with sun-related conditions, nursery owners report
damage to plants, a sailor says that his yacht's dacron sails have
become brittle, and a rancher declares that 50 of his sheep,
grazing at high altitudes, suffer "temporary cataracts" in the
spring. (_Newsweek_, 9 December 1991, p. 43; NY Times, 27 July
1991, p. C4; 27 March 1992, p. A7).
Mr.Inconvenient truth is gonna be pissed.
Just think how large it would have grown to, if not for all the personal things Algore did to combat Gorebull warming.
All hail Algore
I guess that ozone surge is working. Nice fishing spot on your page.
That Dobson is really pi$$ing me off. First he disses Thompson and now this
Well that puts a hole in global warming. A big one
Hopefully, someday these “scientists” will figure out that the ozone hole expands and contracts and there is not a damn thing man can do about it.
We need to bring back R-12 and hairspray. That’ll fix it.
“Hopefully, someday these “scientists” will figure out that the ozone hole expands and contracts and there is not a damn thing man can do about it.”
Never happen. Those minds believe man can destroy everything and man can fix everything. It’s a deluded arrogance commonly accompanied by a lack of belief in any deity.
This was on Valentine today and the way it was explained to him was “it’s a thermostat” so just let it operate as usual and don’t “mess” with it. We started messing with it years ago unfortunatly.
Maybe now they can use the right insulation ( made with CFCs ) on the Space Shuttle that they used back in the 80’s that really worked and didn’t fall apart.
Mother Earth has done her Kegels well.
This means I’ll have to try harder next year.
Now we must stop our use of these chemicals (for the time being), AND stop purposely attacking the ozone for the sake of science, in order for Earth to heal.
Al Gore is full of it.
I like small ozone holes.
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