1. Stratospheric Ozone Brent Greenhalgh and Carrie Welker Reviews in Earth Science Oct. 4, 2011 September 17, 1979 October 1, 2010 (NASA, 2011-1)

2. Natural State of Stratospheric Ozone Ozone (O 3 ) is very small part of atmosphere ~90% of ozone is in the stratosphere Protects life from solar UV radiation Inverse T profile in stratosphere Total ozone ranges from 200-500 DU UV radiation O 3  O 2 + O + heat

3. Natural variation of stratospheric ozone 1) Air Motions Ozone changes with latitude from stratospheric wind patterns Weather systems 2) Chemical 11-year solar cycle causes 1-2% change in ozone Volcanic eruptions deplete ozone for a few years

4. Anthropogenic Change (NASA, 2011-1)

5. Montreal Protocol & Projections (U.N, n.d.)