what is ozone? why should we care about something we can’t see? dr. michael j passow earth2class...
TRANSCRIPT
What Is Ozone? Why Should We Care about Something We Can’t See?
Dr. Michael J PassowEarth2Class Introduction
19 Oct 2013
What is Ozone?
• Simply explained, ozone is a highly reactive form of oxygen molecules O3
Ozone poses two biological problems, depending on whether it is:• “Tropospheric Ozone” or• “Stratospheric Ozone”
Tropospheric Ozone
• Produced mainly by reaction of sunlight, oxygen, and exhaust from combustion engines (hydrocarbons/nitrogen oxides)
• Major component of photochemical smog• Dangerous to people with respiratory ailments• Also damages plants, especially in North
American and European forests
Stratospheric Ozone
• Above 11 km (7 mi)• “Ozone Shield” protects against solar
ultraviolet radiation• Satellites have monitored significant declines
over past few decades• Most noticeable declines over Antarctica• “Peaked” (?) in 2006
Progress in Monitoring
• 1979 – 1993: NASA/NOAA Nimbus-7
• 1993 – 1994: Metor-3 (USSR)
• 1996 – 2004: NASA Earth Probe TOMS
• 2004 – present: OMI instrument aboard Aura (KNMI/NASA)
NASA Ozone Monitoring
NIMBUS-7 TOMS INSTRUMENT AND SATELLITE INFORMATIONhttp://ozoneaq.gsfc.nasa.gov/n7sat.md
Other satellites and platforms (balloon sondes)
Nimbus 7 Satellite
http://ozoneaq.gsfc.nasa.gov/displayImage.md?image=n7art.gif&alt=Nimbus-7%20Drawing
Ozone Hole Watch• NASA provides info
about O3 maps, meteorology, facts, multimedia, and education
http://ozonewatch.gsfc.nasa.gov/
What Probably Created the Ozone Hole?
Chlorofluorocarbons (CFCs)• Synthetic hydrocarbons in which H is replaced by
halogens (e.g., CHF2Cl, CFCl3, CF2Cl2)• Also, Br compounds• Widely used refrigerants and propellants• In the atmosphere, may take 60 – 100 years to
decompose• 1987 Montreal Protocol established scheduled
reduction in use
What Else Depletes Ozone?
• Nitrous Oxide (N2O)• Like CFCs, stable in stratosphere and able to
deplete O3
• Unlike CFCs, 60% derived from natural sources >decomposition of N compounds in soil and water >burning fossil fuels & plants (deforestation) >use of manure, fertilizers on crops
Some Dangers of N2O
• Montreal Protocol does not regulate N2O• In troposphere, potent greenhouse gas
(~300 x as potent as CO2)• Impact on ozone hole not definitively
established, but of concern to scientists
Ozone Hole History
• ://www.theozonehole.com/ozoneholehistory.htm
NOAA’s Ozone Page
• http://www.oar.noaa.gov/k12/html/ozone2.html
References
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/O/Ozone.htmlhttp://ozoneaq.gsfc.nasa.gov/n7sat.mdhttp://ozonewatch.gsfc.nasa.gov/http://blogs.agu.org/wildwildscience/files/2011/05/ozone_hole_large.jpghttp://www.theozonehole.com/ozoneholehistory.htmhttp://www.oar.noaa.gov/k12/html/ozone2.html