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The Stratospheric Chemistry and The Ozone Layer

The Stratospheric Chemistry and The Ozone Layer. *Stratospheric circulation *Stratospheric photochemistry *Gas phase reactions *Ozone and Catalytic cycles. Dr Tony Cox ERCA 2004 -Lecture 2. Temperature Structure of the Atmosphere. Mesosphere. Stratopause. Height/km. Stratosphere.

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The Stratospheric Chemistry and The Ozone Layer

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  1. The Stratospheric Chemistry and The Ozone Layer *Stratospheric circulation *Stratospheric photochemistry *Gas phase reactions *Ozone and Catalytic cycles Dr Tony Cox ERCA 2004 -Lecture 2

  2. Temperature Structure of the Atmosphere

  3. Mesosphere Stratopause Height/km Stratosphere Tropopause Troposphere Latitude

  4. Black region is troposphere Eruption of Mt Pinatubo, Phillipine Is, 5ON, June 1991 Satellite measurements of aerosol as a tracer for stratospheric circulation

  5. Mesosphere Stratosphere Upper troposphere

  6. MEAN (11yr) ATMOSPHERIC WINDS AT 20 km ALTITUDE (NOAA Analysis)

  7. MEAN (11yr) ATMOSPHERIC TEMPERATURE AT 20 km ALTITUDE (NOAA Analysis)

  8. Potential Vorticity At ~20 km in the S.Polar Vortex

  9. 30 km Altitude 16 km 1950 The QBO In equatorial regions 1978

  10. Variations in mean O3 column(DU) due to QBO (from satellite observations)

  11. Climatology of Global O3 column (after Dutsch, 1971) In Dobson units, i.e. mmHgx100 at STP

  12. Chemical Kinetics I

  13. Chemical Kinetics II

  14. Chemical Kinetics III

  15. O(3P) O3 O2 O3

  16. Window region where UV radiation penetrates into the lower stratosphere giving: O2 + hn  O + O

  17. Chemical lifetime of O3:calculated daily averaged photodissociation rate of molecular oxygen

  18. Release of catalysts by Photolysis in the lower Stratosphere

  19. O2 + hn(l<243nm)  O + O oxygen photolysis O + O2 + M O3 + Mozone formation O + O3 O2 + O2 ozone destruction O3 + hn(l<310nm)  O(1D) + O2 O3 + hn(l<1180nm)  O + O2 oxygen photolysis NO2 + hn(l<243nm)  NO + O NO2 photolysis O + O2 + M O3 + Mozone formation X + O3 XO + O2 XO + O  X + O2 Net O + O3 O2 + O2 ozone destruction [X = H, OH, NO, Cl, Br, etc]

  20. Interconversion of Cl & ClO Formation and release from reservoirs of Cl & ClO

  21. STRATOSPERE  heterogeneous reactions on sulphate aerosol

  22. OZONE DEPLETION CYCLES IN THE LOWER STRATOSPHERE Concentration of O atoms fall off in lower stratosphere as photolysis of O2 and O3 reduces. Catalytic destruction through cycles involving participation of atomic O is less important. Other cycles not involving O(3P) can occur.

  23. OZONE DEPLETION CYCLES INVOLVING HALOGENS THE LOWER STRATOSPHERE Involving ClOx/NOx coupling ClO + NO2 = ClONO2 ClONO2 + hn = Cl + NO3 NO3 + hn = NO + O2 NO + O3 = NO2 + O2 Cl + O3 = ClO + O2 net O3 + O3 = 3O2 Involving NOx/Halogen (X = Br or I) coupling XO + HO2 = HOX + O2 HOX + hn = X + HO OH + O3 = HO2 + O2 X + O3 = XO + O2 net O3 + O3 = 3O2

  24.  heterogeneous reactions on sulphate aerosol

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