Please Register or Log in to view the hidden image! WASHINGTON (AP) — This year's Antarctic ozone hole is the biggest ever, government scientists said Thursday. The so-called hole is a region where there is severe depletion of the layer of ozone — a form of oxygen — in the upper atmosphere that protects life on Earth by blocking the sun's ultraviolet rays. Scientists say human-produced gases such as bromine and chlorine damage the layer, causing the hole. That's why many compounds such as spray-can propellants have been banned in recent years. "From Sept. 21 to 30, the average area of the ozone hole was the largest ever observed, at 10.6 million square miles," said Paul Newman, atmospheric scientist at NASA's Goddard Space Flight Center, Greenbelt, Md. That's larger than the area of North America. In addition, satellite measurements observed a low reading of 85 Dobson units of ozone on Oct. 8. That's down from a thickness of 300 Dobson units in July. The ozone hole is considered to be the area with total column ozone below 220 Dobson Units. A reading of 100 Dobson Units means that if all the ozone in the air above a point were brought down to sea-level pressure and cooled to freezing it would form a layer 1 centimeter thick. A reading of 250 Dobson Units translates to a layer about an inch thick. In a critical layer of air between eight and 13 miles above the surface, the measurement was only 1.2 Dobson unit, down from 125 in July. "These numbers mean the ozone is virtually gone in this layer of the atmosphere," said David Hofmann, director of the Global Monitoring Division at the National Oceanic and Atmospheric Administration's Earth System Research Laboratory. "The depleted layer has an unusual vertical extent this year, so it appears that the 2006 ozone hole will go down as a record-setter." The size and thickness of the ozone hole varies from year to year, becoming larger when temperatures are lower. Because of international agreements banning ozone-depleting substances, researchers calculated that these chemicals peaked in Antarctica in 2001 and have been declining. However, many of them have extremely long lifetimes once released into the air. While there are year-to-year variations, scientists expect a slow recovery of the ozone layer by the year 2065, anticipating declines in the use of damaging chemicals. Source
Yes , I just read it today - and I felt sad .... I hope it is true, that a slow recovery of the ozone layer will happen ...
this is good news! soon, i'll be able to barbeque without actually lighting up the grill! I'll just let it soak up the rays!
that's unfortunate; the hole's size had looked like it was leveling off. Please Register or Log in to view the hidden image!
Why don't these geniuses tell us how many Dobson units are over the equator at any given time? Also, how about assigning an SPF to the number of Dobson units of ozone? Yes, of course the ozone layer is important, but it is about 40 kilometers thick and from 2 to 8 parts per million ozone. For the amount of protection against UV I would look at the other 999,992 parts per million. Being as the rest of the substances in the ozone layer mass more than 100,000 times more than the ozone, there is a good chance that a substance like diatomic oxygen, even with a lower shielding factor, is the actual shield against UV radiation.
Correlation between the ozone layer and UV-B reaching the surface: Please Register or Log in to view the hidden image! From: Echer, E., & Kirchhoff, V.W.J.H., 2000, A comparision of direct and global UV-B X Ozone anticorrelations, Proceedings of the SPARC 2000 2nd General Assembly of the SPARC/WCRP Project, Argentina, Nov 6-10 2000.
the slow effect of Montreal protocol...took its positive toll on ozone. so humans do have a chance Please Register or Log in to view the hidden image! And I thought of marching with penguins before they were all gone...
Try here. <img src="ftp://toms.gsfc.nasa.gov/pub/omi/images/global/FULLDAY_GLOB.PNG" alt="OMI Total ozone Oct 26 2006" width=640 height=480 />
