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Unformatted text preview: 1 1 ATM 6, Lecture #18 Cort Anastasio Atmospheric Science Program University of California - Davis Stratospheric Ozone Depletion or “The Ozone Hole” Part II: O 3 Destruction 2 The Stratospheric O 3 Budget: I, Overview • Recall how O 3 is formed in the stratosphere O 2 + light → O + O 2 (O + O 2 → O 3 ) Net rxn: 3 O 2 + light → 2 O 3 (Is this how O 3 is formed in the troposphere? Why?) • O 3 is also naturally destroyed in the stratosphere Net rxn: O 3 + O → 2 O 2 (destruction of two “odd” oxygens) where X = NO (nitric oxide), OH, Cl (chlorine atom) or Br (bromine atom) • “Odd oxygen” = O + O 3 (“even” oxygen = O 2 ) – Ozone formation reactions increase the amount of odd oxygen – Ozone destruction reactions decrease the amount of odd oxygen 2 3 The Stratospheric O 3 Budget (II) • In the past, the overall ozone budget in the stratosphere has been balanced • What will happen to the concentration (amount) of stratospheric O 3 if… Source rate = sink rate? Source rate < sink rate? Source rate > sink rate? Fig. 13.2 A simple box model for odd oxygen in the stratosphere. (Gt = gigatonne = 10 9 tonnes = 10 12 kg) Concentration will ______________ Concentration will ______________ Concentration will ______________ • What is our current problem with stratospheric O 3 and why? – We have increased the rate of destruction of O 3 – This is because we have increased the concentrations of sinks (X) • (What is our current problem with global warming and why?)• (What is our current problem with global warming and why?...
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- Fall '07
- Ozone depletion, CFC, Stratospheric O3 Destruction