Stratospheric Ozone Depletion and Antarctic Ozone Hole
Stratospheric ozone plays a very significant role in the radiation balance of the Earth-atmosphere system and also protects life on the Earth’s surface from harmful UV radiation. Changes in stratospheric ozone levels can affect human health and ecosystem as well as the chemistry of the troposphere.
In Chapter 5, we have seen that the atmospheric ozone can be destroyed by a number of free radical catalysts, the most important of which are the hydroxyl radical (OH), the nitric oxide radical (NO), and atomic chlorine (Cl) and bromine (Br). All these have both natural and anthropogenic (man-made) sources. At the present time, most of the OH and NO in the stratosphere is of natural origin, but human activity has dramatically increased the high concentration of carbon dioxide, chlorine, and bromine. These elements are found in certain stable organic compounds, especially chlorofluorocarbons (CFCs), which may find their low reactivity. Once the Cl and Br atoms are liberated from the parent compounds by the action of UV light, it remains in the stratosphere for a longer period and goes on destroying ozone in this region.
A single chlorine atom would keep on destroying ozone for up to 2 years, the timescale required to transport back down to the troposphere, were it not for reactions that remove them from this cycle by forming reservoir species such as hydrogen chloride (HCL) and chlorine nitrate (ClONO2). On a per atom basis, bromine is even more efficient than chlorine at destroying ozone, but there is much less bromine present in the atmosphere. As a result, both chlorine and bromine contribute significantly to the overall ozone depletion. Laboratory studies have shown that fluorine and iodine atoms participate in analogous catalytic cycles. However, in the Earth’s stratosphere, fluorine atoms react rapidly with water and methane to form strongly bound HF, while organic molecules which contain iodine react so rapidly in the lower atmosphere that they do not reach the stratosphere in significant quantities.
KeywordsMethane Foam Iodine Explosive Smoke
Unable to display preview. Download preview PDF.
- Brasseur G, Solomon S (2005) Aeronomy of the Middle Atmosphere, 2nd edition, Springer, DordrechtGoogle Scholar
- Dameris M, Grewe V, Ponater M, Deckert R, Eyring V, Mager F, Matthes S, Schnadt C, Stenke A, Steil B, Bruhl C, Giorgetta MA (2005) Long-term changes and variability in a transient simulation with a chemistry climate model employing realistic forcing, Atmos Chem Phys, 5: 2121–2145Google Scholar
- Eduspace, The ozone hole, European Space Agency (http://eduspace.esa/int/subdocument/images/ozone-gen.jpg)
- Huck PE, McDonald AJ, Bodeker GE, Struthers H (2005) Interannual variability in Antarctic ozone depletion controlled by planetary waves and polar temperatures, Geophys Res Lett, 32: doi 10.1029/2005GL022943Google Scholar
- Fromm M, Bevilacqua R, Servranckx R, Rosen J, Thayer JP, Herman J, Larko D (2005) Pyrocumulonimbus injection of smoke to the stratosphere: Observations and impact of a super blowup in northwestern Canada on 3–4 August 1998, J Geophys Res, 110: D08205, doi 10.1029/2004- JD005350CrossRefGoogle Scholar
- Maduro RA, Schauerhammer R (1992) The holes in the ozone scare: the scientific evidence that the sky is not falling, In 21st Century Science Associates, John Wiley & Sons, Washington DCGoogle Scholar
- NASA (2003) Studying Earth’s Environment from Space (http://www.ccpo.odu.edu/SEES/index.html)
- Newman PA (2003) The Antarctic ozone hole, Chapter 11: Stratospheric Ozone: An Electronic Text, NASA, GSFCGoogle Scholar
- Newman PA, Kawa SR, Nash ER (2004) On the size of the Antarctic ozone hole, Geophys Res Lett, 31: doi 10.1029/2004GL020596Google Scholar
- Newman PA, Nash SR, Kawa ER, Montzke SA (2006) When will the Antarctic ozone hole recover? Geophys Res Lett, 33: doi. 10.1029/2005GL025232Google Scholar
- Ramaswamy V, Chanin ML, Angell JK, Barnett J, Gaffen D, Gelman ME, Keckhut P, Koshelkov Y, Labitzke K, Lin JJR, ONeill A., Nash J, Randel WJ, Rood R, Shine K, Shiotani M, Swinbank R (2001) Stratospheric temperature trends: Observations and model simulations, Rev Geophys, 39: 71–122CrossRefGoogle Scholar
- Rowland RF (2007) Stratospheric ozone depletion by chlorofluorocarbons (Nobel Lecture), Appeared in Encyclopedia of Earth (ed; C. J. Cleveland)Google Scholar
- Santee MI, Manney GL, Livesey NJ, Froidevaux L, MacKenzie IA, Pumphrey HC, Read WG, Schwartz MJ, Waters JW, Harwood RS (2005) Polar processing and development of the 2004 Antarctic ozone hole: First results from MLS on aura, Geophys Res Lett, 32, doi 10.1029/2005GL022582Google Scholar
- Steinbrecht W, Hassler B, Bruhl C, Dameris M, Giorgetta MA, Grewe V, Manzini E, Matthes S, Schnadt C, Steil B, Winkler P (2006) Interannual variation pattern of total ozone and lower stratospheric temperature in observations and model simulations, Atmos Chem Phys, 6: 349–374Google Scholar
- Stolarski RS, McPeters RD, Newman PA (2005) The ozone hole of 2002 as measured by TOMS, J Atmos Sci, 62: 716–720 (http://www.eoearth.org/Rowland_nobel_lecture_fig05.gif)Google Scholar
- Stolarski RS, Douglass AR, Newman PA, Pawson S, Schoeberl MR (2006) Relative contribution of greenhouse gases and ozone changes to temperature trends in the stratosphere: A chemistry-climate model study NASA Report Document ID: 20070008218Google Scholar
- WMO (1995) Scientific Assessment of Ozone Depletion: 1994, Global Ozone Research and Monitoring Project Report No. 37, Geneva, SwitzerlandGoogle Scholar
- WMO (World Meteorological Organization), Scientific Assessment of Ozone Depletion: 2006 (2007) Global Ozone Research and Monitoring Project Report No. 50, Geneva, SwitzerlandGoogle Scholar