From the Massachusetts Institute of Technology
Plugging an ozone hole
MIT researchers find that the extremes in Antarctic ozone holes have not been matched in the Arctic
CAMBRIDGE, Mass– Since the discovery of the Antarctic ozone hole, scientists, policymakers, and the public have wondered whether we might someday see a similarly extreme depletion of ozone over the Arctic.
But a new MIT study finds some cause for optimism: Ozone levels in the Arctic haven’t yet sunk to the extreme lows seen in Antarctica, in part because international efforts to limit ozone-depleting chemicals have been successful.
“While there is certainly some depletion of Arctic ozone, the extremes of Antarctica so far are very different from what we find in the Arctic, even in the coldest years,” says Susan Solomon, the Ellen Swallow Richards Professor of Atmospheric Chemistry and Climate Science at MIT, and lead author of a paper published this week in the Proceedings of the National Academy of Sciences.
Frigid temperatures can spur ozone loss because they create prime conditions for the formation of polar stratospheric clouds. When sunlight hits these clouds, it sparks a reaction between chlorine from chlorofluorocarbons (CFCs), human-made chemicals once used for refrigerants, foam blowing, and other applications — ultimately destroying ozone.
“A success story of science and policy”
After the ozone-attacking properties of CFCs were discovered in the 1980s, countries across the world agreed to phase out their use as part of the 1987 Montreal Protocol treaty. While CFCs are no longer in use, those emitted years ago remain in the atmosphere. As a result, atmospheric concentrations have peaked and are now slowly declining, but it will be several decades before CFCs are totally eliminated from the environment — meaning there is still some risk of ozone depletion caused by CFCs.
“It’s really a success story of science and policy, where the right things were done just in time to avoid broader environmental damage,” says Solomon, who made some of the first measurements in Antarctica that pointed toward CFCs as the primary cause of the ozone hole.
To obtain their findings, the researchers used balloon and satellite data from the heart of the ozone layer over both polar regions. They found that Arctic ozone levels did drop significantly during an extended period of unusual cold in the spring of 2011. While this dip did depress ozone levels, the decrease was nowhere near as drastic as the nearly complete loss of ozone in the heart of the layer seen in many years in Antarctica.
The MIT team’s work also helps to show chemical reasons for the differences, demonstrating that ozone loss in Antarctica is closely associated with reduced levels of nitric acid in air that is colder than that in the Arctic.
“We’ll continue to have cold years with extreme Antarctic ozone holes for a long time to come,” Solomon says. “We can’t be sure that there will never be extreme Arctic ozone losses in an unusually cold future year, but so far, so good — and that’s good news.”
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WRT O2 magnetic susceptibility, this is not a function of the state of the oxygen (gas liquid solid) but rather the molecular orbitals involved in the bonding. Oxygen molecules have two unpaired electrons with parallel spins in the two pi* orbitals. This makes O2 paramagnetic, e.g. having high magnetic susceptibility
See
http://www.chem.queensu.ca/people/faculty/mombourquette/firstyrchem/molecular/orbitals/index.htm
towards the bottom or look under molecular orbitals in any GChem book.
Thanks Phil; I’ll look up that stuff. It would seem that The Michael J. Hollas book, is not among the 200 odd Physics Texts on my bookshelf; I can’t buy them all. I even have a couple on Chemistry; one by Linus Pauling. I was privileged to attend a lecture by him on the chemistry and molecular structure of sickle cell anemia; which I’m given to understand was the first disease specifically attribute to the shape of a specific molecule; in this case, haemoglobin. I’m sure WUWT readers think I just make this stuff up, since I virtually never either read or cite Wikipedia, the standard yuppie reference for everything.
On radiation Physics, my most complete reference is “The Infra-Red Handbook” Third Printing
edition from ERIM for the US Navy. In their section 3-4 on the sun as a natural light source, they give a table and plot of the extra-terrestrial solar spectrum. Much of the material was generated by the US Air Force, and the published extra-terrestrial solar spectrum table, which is table 3-17 in the book, and plotted as fig. 3-6, which also includes the sea level; air mass one solar spectrum.
The specific paper reference; 3-28, is by M.P. Thekakara; “Evaluating light from the Sun.” Optical Specta, Optical Publishing, Pittsfield Mass, Vol 6 No 3 March 1972 pp32-35
That reference pegs the peak of the ex-earth spectrum at 485 nm, which the 1931 CIE chromaticity diagram saya is blue; not green.
And Thekakara’s air mass one sea level solar spectrum, shows an O3 absorption band from about 480 nm up to 680 nm, which is just on the long wavelength side of the 450 nm (blue) peak of the sea level solar spectrum. I believe I said essentially that in my first response to Eli Rabbett above.
Yes it does show an O3 absorption band from 250 to 300 nm, which I presume is identical with the continuum band that Eli and Phil refer to.
As I said above, I understand how ionized gases produce continuum spectra, beyond the usual atomic line spectra, since the captured electron by the originally ionized atom, can have any value of energy whatsoever; but I don’t see how a neutral atom, can produce a continuum spectrum from “excited states”, which would seem by definition to produce line spectra. And Thermal continuum spectra, due to molecular collisions, in gases, are of course low energy photons; not UV.
And I still for the life of me don’t see what any of this has to do with the Stefan Boltzmann Law that Eli mentioned in his post.
But thanks Phil for the citations; seems like I need a newer radiation Physics Text book.
I’ve paid enough money as a taxpayer, that NASA/NOAA should give me one.
This is a not bad image of the solar spectrum overlaid with a black body spectrum showing, that if anything the solar spectrum is UV poor and IR rich by a small amount
http://en.wikipedia.org/wiki/File:EffectiveTemperature_300dpi_e.png
Most of the sharp lines in the solar spectrum are atomic (metal) absorptions in the solar atmosphere.
The spectrum at the bottom of the atmosphere shows a number of water vapor and carbon dioxide overtone and combination bands in the NIR (between 700 and 4000 nm)
http://www.calpoly.edu/~rfield/SolarFlux.htm
Finally, you have to be careful comparing spectra taken at different resolutions, because the lower resolution stuff smears out the bands.
Can’t even keep up. Hollas is very good.
Also
“A reaction between chlorine and what? What is the sound of one hand clapping?”
To start a lot of the Cl atoms in the stratosphere are tied up in the adduct ClONO2. This species decomposes on the polar stratospheric cloud particles and basically gets turned into nitric acid, HNO3, and Cl2. At first light the Cl2 falls apart to give a huge pulse of Cl. You need light in the 300-400 nm region to dissociate the Cl2 which is why the hole appears in the spring and not the winter
Cl + O3 –> ClO + O2
ClO + ClO + M –> Cl2O2 + M
Cl2O2 + hv –> Cl + ClO2
ClO2 + M –> Cl + O2 + M
and around you go
Summary of all this
http://www.atmos.washington.edu/academics/classes/2011Q2/558/solomon1999.pdf
george e. smith says:
April 17, 2014 at 9:23 pm
Thanks Phil; I’ll look up that stuff. It would seem that The Michael J. Hollas book, is not among the 200 odd Physics Texts on my bookshelf; I can’t buy them all. I even have a couple on Chemistry; one by Linus Pauling. I was privileged to attend a lecture by him on the chemistry and molecular structure of sickle cell anemia; which I’m given to understand was the first disease specifically attribute to the shape of a specific molecule; in this case, haemoglobin.
Right and due to a mutation in a single base!
I’m sure WUWT readers think I just make this stuff up, since I virtually never either read or cite Wikipedia, the standard yuppie reference for everything.
I often cite Wikipedia because other posters complain if I cite papers!
As I said above, I understand how ionized gases produce continuum spectra, beyond the usual atomic line spectra, since the captured electron by the originally ionized atom, can have any value of energy whatsoever; but I don’t see how a neutral atom, can produce a continuum spectrum from “excited states”, which would seem by definition to produce line spectra.
Here’s the potted version George.
As a result of LCAO (linear combination of atomic orbitals) there are a variety of excited electronic states (molecular orbitals), some are bonding and others antibonding. The antibonding ones don’t have an energy well so there’s no bond between the two atoms to vibrate and therefore no energy levels. Consequently when excited, any energy is accessible, hence the continuum.
There are some relevant diagrams here:
http://en.wikipedia.org/wiki/Molecular_orbital_diagram
But thanks Phil for the citations; seems like I need a newer radiation Physics Text book.
I’ve paid enough money as a taxpayer, that NASA/NOAA should give me one.
You’re welcome, good luck with that. 🙂
Well actually NASA has 🙂
http://www.ccpo.odu.edu/~lizsmith/SEES/ozone/oz_class.htm
Stratospheric Ozone Textbook
Eli’s Wiki graph, is better resolution than the my 1972 graph, but mine looks otherwise like a slightly smoothed version of Eli’s; the near peak anomalous stuff has somewhat the same characteristics.
And Thekakara gives 5770 K for the TSI matching BB Temperature; but in those days, and further back in my school days TSI was 1353 W/m^2 But that was almost certainly based on balloon and rocket measured data, corrected for the presumed residual atmosphere He gives 5900 K for the best BB shape fit Temperature.
Wiki’s graphs, are not a good shape fit at 5777 K.
Amazing how those ancients got so close. He also shows the 700 nm region water band, and an Oxygen and water band overlapping (bands) at around790 nm, then lots of water bands from 830 to 2.0 microns and beyond, with CO2 first showing at 1.5 and 1.9 microns and 2.5 microns.
Somewhere, I have seen solar spectrum curves, way out to the radio region, and way down in the mud, by orders of magnitude. They are not continuous, and they don’t all correspond to the same Temperature.
There’s some million degree sections in there, which I presume come from coronal regions..
Thanks Eli and Phil, anyway for the references; I can see I need some more books.
The Stanford Bookstore, only seems to carry what the profs are teaching from, and usually writing themselves.