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The Importance of Ozone Layer: Facts and Effects

Learn about the polar stratospheric ozone, atmospheric composition, ozone facts, health impacts of UV radiation, and the role of chlorofluorocarbons in ozone depletion. Discover essential ozone facts and the impact on Earth's atmosphere.

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The Importance of Ozone Layer: Facts and Effects

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  1. Jan. 10, 2003 - local noon, Kiruna, Sweden

  2. Jan. 14, 2003 Southern Norway

  3. Polar Stratospheric Ozone Dr. Paul A. Newman http://code613-3.gsfc.nasa.gov/People/Newman/ NASA’s Goddard Space Flight Center IPY Webcast NASA GSFC Nov. 3, 2008

  4. Ozone Oxygen Ozone Basic Facts O3 = Ozone is composed of 3 oxygen atoms. O3 concentrations are small (peak concentrations are about 10 parts per million at an altitude of about 32 km (20 miles). O3 absorbs harmful solar ultraviolet radiation. A necessary condition for life. O3 is mainly found in the the stratosphere. O3 at the ground is a problem! Inhalation of ozone for very small concentrations can cause lung problems . Mass: (Billion Metric Tons) Sun 1,9900,000,000,000,000,000 Earth 5,980,000,000,000 Global atmosphere 5,300,000 Global ozone 3

  5. Atmospheric Composition • Nitrogen 78.1% • Oxygen 20.9% • Argon 0.9% • Water 1.4% (tropics) 0.2% (poles) 0.0004% (stratosphere) • CO2 0.0360% • O3 0.001% (stratosphere) 0.00001% (troposphere)

  6. Atmospheric Structure -135oF -99oF -63oF -27oF 9oF 45oF 81oF 100 60 80 50 40 60 Altitude (km) Altitude (miles) 30 40 20 20 10 0 0 180 200 220 240 260 280 300 Temperature (K) Thermosphere Mesosphere Stratosphere Troposphere

  7. Atmospheric Structure 100 60 80 50 40 60 Altitude (km) Altitude (miles) 30 40 20 20 10 0 0 Thermosphere Mesosphere Stratosphere Airliners fly at 30,000-40,000 feet Troposphere

  8. Atmospheric Structure 100 60 80 50 40 60 Altitude (km) Altitude (miles) 30 40 20 20 10 0 0 Thermosphere Mesosphere ER-2 flies at 70,000 feet Stratosphere Troposphere

  9. Atmospheric Structure 100 60 80 50 40 60 Altitude (km) Altitude (miles) 30 40 Ozone Oxygen 20 20 10 0 0 Thermosphere Mesosphere Stratosphere Troposphere

  10. Ozone Facts 100 60 80 50 40 60 Altitude (km) Altitude (miles) 30 40 20 20 10 0 0 Thermosphere Mesosphere 90% of ozone is in the stratosphere Troposphere 0 2 4 6 8 Ozone (parts per million)

  11. Ozone Facts 100 60 80 50 40 60 Altitude (km) Altitude (miles) 30 40 20 20 10 0 0 Thermosphere Mesosphere Stratosphere 10% of ozone is in the troposphere 0 2 4 6 8 Ozone (parts per million)

  12. Digression: Dobson Units • Total Ozone is a measure of the total column amount above us. Measured in Dobson Units • If we bring all of the ozone above us down to the Earth’s surface • The thickness would be about 3 millimeters (~0.1 inches) = 300 Dobson Units (approximately the global average) • 100 Dobson Units = 1 millimeter in thickness ozone layer 2¢ 10¢ 3 mm = 300 Dobson Units • The Dobson Unit is a convenient unit of measurement for total column ozone

  13. Ozone Facts 100 60 80 50 40 60 Altitude (km) Altitude (miles) 30 40 20 20 10 0 0 Ozone is the Earth’s natural sunscreen UVc - 100% Absorption UVb - 90% Absorption UVa - 50% Absorption & Scattering Stratosphere 0 2 4 6 8 Ozone (part per million)

  14. UV Health Facts • UV pluses: produces vitamin D in the skin - necessary to maintain levels of calcium and phosphorus (10-15 minutes twice a week) • UV minuses: • Eye damage: cataracts, photokerititus (snowblinding), ocular cancers • Skin cancers: basal, squamous, melanoma • photoaging • Damage to various land speciesDamage to aquatic species • Increased pollution levels in urban environments Cataract Melanoma Mexico City

  15. Large polar ozone losses result from chlorine and bromine compounds that are mainly human produced

  16. Chlorine Pathway Cl catalytically destroys O3 Cl reacts with CH4 or NO2 to form non-reactive HCl or ClONO2 CFC-12 photolyzed in stratosphere by solar UV, releasing Cl Carried into stratosphere in the tropics by slow rising circulation Polar loss CFC-12 released in troposphere

  17. Source Gases • Cl is much more abundant than Br, but … • Br is about 60 times more effective at O3 destruction From Ozone FAQ - see http://www.unep.org/ozone/faq.shtml

  18. Atmospheric Chlorine Trends from NOAA/ERL - Climate Monitoring Division 102 years CFC-12 CFC-11 50 years CCl4 42 years 85 years CFC-113 CH3CCl3 5 years Updated Figure made by Dr. James Elkins from Trends of the Commonly Used Halons Below Published by Butler et al. [1998], All CFC-113 from Steve Montzka (flasks by GC/MS), and recent updates of all other gases from Geoff Dutton (in situ GC).

  19. Polar Stratospheric Clouds Central, Sweden January 14, 2003 - P. Newman

  20. HCl PSC ClONO2 Cl2 HNO3 Antarctic ozone hole theory Solomon et al. (1986), Wofsy and McElroy (1986), and Crutzen and Arnold (1986) suggest reactions on cloud particle surfaces as mechanism for activating Chlorine Cl2 is easily photolyzed by UV & blue/green light HNO3 is sequestered on PSC

  21. Polar Ozone Destruction 1. O3 + Cl ClO + O2 3. ClOOCl+h2 Cl+O2 2 O3 3 O2 2. 2 ClO + M ClOOCl + M Only visible light (blue/green) needed for photolyzing ClOOCl No oxygen atoms required Net: 2O3 + h  3O2

  22. Antarctic Measurements Aurora over Halley Bay Station, Antarctica, 75.6ºS 26.5ºE Brunt Ice Shelf, Coats Land 105 days of continuous darkness, twice per year re-supply Population: 65 in summer, 15 in winter

  23. October Antarctic Ozone pre-1985

  24. October Antarctic Ozone

  25. Antarctic ozone hole is defined as the region covered by low ozone values Orange/Yellow indicates higher ozone levels. Dark color over pole shows the extent of polar night, no ozone observations Blue colors indicate low ozone values TOMS - August 31, 2003

  26. Sep. 21, 2008 Sep. 30, 2008 1st observed SH major warming (2002) Ozone Hole Area N. America

  27. October Average Ozone Hole

  28. March Average total ozone

  29. Arctic & Antarctic Trends

  30. What’s being done?

  31. What Can You Do? • Avoid excessive solar exposure (limit sun between 11AM and 2PM). • Wear and encourage others to wear sunscreen (SPF rating of 15). Even with sunscreen, prolonged exposure is not smart. • Check your skin regularly. • Wear sunglasses that screen UV. • Hats and other coverings • Make note of the UV index on the news or web: http://www.epa.gov/sunwise/uvindex.html

  32. U. S. CFC production stopped by President George Bush in 1992 Montreal Protocol Signed (1987) Atmospheric Chlorine Trends from NOAA/ERL - Climate Monitoring Division 102 years CFC-12 CFC-11 50 years CCl4 42 years 85 years CFC-113 CH3CCl3 5 years Updated Figure made by Dr. James Elkins from Trends of the Commonly Used Halons Below Published by Butler et al. [1998], All CFC-113 from Steve Montzka (flasks by GC/MS), and recent updates of all other gases from Geoff Dutton (in situ GC).

  33. Recovery of 1970 Antarctic EESC in 22nd century! Antarctic EESC Obs. Projections Using WMO scenario A1-adj., we can project forward from 1980 to show recovery of EESC around 2065.

  34. Ozone future Projected area of the ozone hole

  35. Summary • Stratospheric ozone is a critical gas for screening solar UV radiation. • Human produced ozone destroying substances (ODS) have caused large losses of polar ozone over both poles • ODSs have been regulated under international agreements and are slowly decreasing. Ozone levels should recover within the next 50-70 years. • Climate change remains a big unknown for ozone recovery

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