Stratospheric Chemistry in a nutshell II: Polar Ozone Chemistry ...

Stratospheric Chemistry in a nutshell II:
Polar Ozone Chemistry: Examples of Catalytic Cycles
1970 Crutzen
NO + O3 NO2 + O2 NO 2 + O NO + O 2
O3 + h O + O2 Net: 2 O 3 + h h 3 O 2
1987 Molina & Molina
Cl + O O3 ClO + O O2 Cl + O3 ClO + O2 ClO + ClO + M Cl2O 2 2 + M
Cl2O2 + h 2 Cl + O2 Net: 2 O O3 + +h h 3 O O2 17

Stratospheric Chemistry in a nutshell III: Polar Ozone Chemistry (cont’)
1970 Crutzen HNO3+hOH+NO2 NO + O3 NO2 + O2 Deactivation
NO2 + O NO + O2 NO2 + ClO + M ClONO2 + M
O 3 + h O + O 2 CH 4 + Cl HCl + CH 3
Net: 2 O 3 + h 3 O 2
1987 Molina & Molina Activation PSC
Cl + O3 ClO + O2 ClONO2 + Cl- Cl2 + NO -
3
Cl + O O3 ClO + O O2 ClO+ClO+M Cl2O2 + M Cl2 + h 2 Cl
Cl2O2 + h 2 Cl + O2 Net: 2 O 3 + h 3 O 2
1992 McElroy et al. No efficient deactivation
Cl + O3 ClO + O2 NO2 + BrO + M BrONO2 + M
Br + O3 BrO + O2 BrONO2 + Cl- BrCl + NO -
3
ClO+BrO Br + Cl + O 2 BrCl + h Br + Cl
Net: 2 O 3 + h 3 O 2
2
18

O3+O +O
ClO+BrO
HO HO2+O +O3 HO HO2+O +O
NO NO2+O +O
ClO+O
19

Family concept
N 2O CFCs
NO x family
[NOx] = [N] + [NO] +
[NO [NO2] ] + [NO [NO3] ] +
2[N2O5] + …
HNO 3
ClONO 2
HO HOx family
[HO x] = [H] + [OH] +
[HO 2]
H 2O
2
HCl
ClO x family
[ClOx] = [Cl] + 2[Cl2] + [ClO] + 2[Cl 2[Cl2OO 2] ] +
[OClO] + …
20