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Ozone depletion: BrO x -HO x -NO x chemistry

Ozone depletion: BrO x -HO x -NO x chemistry. Dian Putrasahan. Objective. Introduction BrO x chemistry HO x -NO x chemistry Modelling input Results Summary. Introduction. Near total ozone depletion events are due to both physical and chemical mechanism

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Ozone depletion: BrO x -HO x -NO x chemistry

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  1. Ozone depletion: BrOx-HOx-NOx chemistry Dian Putrasahan

  2. Objective • Introduction • BrOx chemistry • HOx-NOx chemistry • Modelling input • Results • Summary

  3. Introduction • Near total ozone depletion events are due to both physical and chemical mechanism • Chemical mechanism include fast catalytic loss driven by bromine oxide radicals (BrOx = Br + BrO) • Presence of aerosols allows heterogeneous reactions that further enhances ozone depletion.

  4. BrOx and O3 Catalytic mechanism for O3 depletion: 2 x (Br + O3→ BrO + O2) BrO + BrO → Br2 + O2 Br2 + hν → 2Br ____________________________________________________________________________________________________________________ Net: 2 O3 → 3 O2 Aerosol effect: Br- + HOBr + H+ → Br2 + H2O Br2 + hν → 2Br

  5. BrOx Chemistry

  6. HOx–NOx chemistry

  7. Modeling of BrOx-NOx-HOx Chemistry • Facsimile Program • Input of 37 reactions (8 aqueous reactions, 5 vapor-liquid equilibrium reactions, 24 gas phase reactions) • Set condition: O3 (5ppbv), Br- (23pptv), BrO (10pptv), NO (2.9pptv), NO2 (2.4pptv) pH (0.5)

  8. BrO and Br effect

  9. BrO Effect

  10. Ozone effect on Br

  11. Ozone effect on Br-

  12. Effects of NOx

  13. Ozone effect on NOx

  14. Summary • Increase in BrO and/or Br will increase the rate of ozone depletion • Br reaches steady state faster as O3 concentration decreases • Br- reaches depletes faster as O3 concentration increases • Increase in NOx concentrations can prevent total ozone depletion • NOx acquires steady state faster as O3 concentration decreases

  15. THANK YOU!!!

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