Stratospheric Chemistry

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Stratospheric Chemistry
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Stratospheric Chemistry - Ozone
Solar Emission 250 1000 um
UV Radiation
UV-A 315- 400nm 7 total solar flux UV-B
280-315nm 1.5 total flux UV-C lt280nm
0.5 total solar flux
Ozone absorbs UV-C and partially absorbs UV-B
region
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Ozone Damage to the Red Alder Tree
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Dobson units (DU) for the measurement of ozone
100 DU equivalent to 1mm thick layer of ozone at
0 oC and Po
World Average 300 DU
Antarctic Ozone Hole lt 150 DU
Range 250 DU 450 DU
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Ground Based Ozone Detection Systems
Dobson Ozone Spectrometer (1920s)
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Stratospheric Ozone Lidar Trailer Equipiment
(STROZ-LITE)
Ozone Two Lasers (308 and 351nm) (light
backscattered elastically, collected with a 30
telescope) Temperature (from 351 nm backscatter,
signal related to density) Aerosol (records both
elastically and inelastically scattered
lightratio gives Aerosol Scatter Ratiomeasure
of aerosol conc.)
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STROZ-LITE Temperature and Aerosol Scattering Data
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Airborne Raman, Ozone, Temperature and Aerosol
Lidar (AROTEL)
Vertical profile of ozone between
12-30km Veritcal profile of temperature, 13
60km Vertical profile of aerosol
scattering Aeosol depolarization at 532 nm
Instrument Transmitter XeCl excimer laser
(308nm) Nd-YAG laser (1064, 532, 355nm) Reciever
16 Newton telescope
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Satellite Remote Sensing
LIDAR Systems, Light Detection and Ranging
Systems
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Satellite-Based Systems
EOS Aura Spacecraft
HIRDLS High Resolution Dynamic Limb
Sounder MLS Microwave Limb Sounder TES
Tropospheric Emission Spectrometer OMI Ozone
Monitoring Instrument
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OMI Data Products
OMI Ozone Monitoring Instrument
OMI Data Products
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OMI Ozone Monitoring Instrument
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Oxygen-only Chemistry formation and turnover of
ozone
First proposed by Chapman
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Chapman Reaction Sequence
O2 hn (l lt 240 nm) ? 2 O 498.4kJ E(hn)
(slow)
O O2 M ? O3 M -106.5kJ (fast)
O3 hn (l 230-320nm) ? O2 O 386.5kJ
E(hn) (fast)
O O3 ? 2 O2 -391.9 kJ (slow)
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Catalytic Decomposition of Ozone
X O3 ? XO O2 XO O ? X O2 O O3 ? 2 O2
X HOx NOx
ClOx 70 _at_ 50km 70 _at_
30km
.H .OH HOO. .NO .NO2 .Cl
ClO.
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HOx Species
Formation O H2O ? 2 .OH
H2O hn ? .H .OH
Catalytic Decomposition of Ozone .H O3 ? .OH
O2 .OH O3 ? HOO. O2 .OH O ? .H
O2 HOO. O ? .OH O2 O O3 ?
2 O2 O O3 ? 2 O2
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NOx Species from N2O (300 ppbv)
Formation lt 30km N2O O ? 2NO
gt30km N2 hn (llt126nm) ? N N N
O2 ? NO O
Catalytic Decomposition of Ozone NO O3 ? NO2
O2 NO2 O ? NO O2 O O3 ? 2 O2
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ClOx Species Natural Source CH3Cl
Formed CH3Cl hn ? .CH3 .Cl Removed
CH3Cl .OH ? .CH2Cl H2O
Catalytic Decomposition of Ozone .Cl
O3 ? ClO. O2 ClO. O ? .Cl O2
O O3 ? 2 O2
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Chlorofluorocarbons (CFCs)
CFC-xyz
x C atoms -1 y H atoms z F
atoms 1 remainder Cl
CFC-114 2 C, 0 H, 4 F .. 2 Cl
114 90 204 .. 2Cl
CFCl2CF3 CF2ClCF2Cl CFC-114a
CFC114b
CFC-11 11 90 101 CFCl3
CFCl3 hn (llt290) ? .CFCl2 .Cl
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Null Cycles Holding Cycles NO O3 ? NO2
O2 NO3 NO2 M ? N2O5 M NO2 hn ? NO
O .NO2 .OH M ? HNO3 M O3 hn ? O2 O .Cl
CH4 ? HCl .CH3 NO2 O3 ? NO3 O2 ClO.
HOO. ? HOCl O2 NO3 hn ? NO2 O HOO.
.NO2 M ? HO2NO2 M O3 hn ? O2 O ClO.
.NO2 M ? ClONO2 M

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Antarctica Ozone Chemistry
Winter HCl ClONO2 ? Cl2 HNO3 (on PSCs) H2O
ClONO2 ? HOCl HNO3 (on PSCs)
Spring Cl2 hn ? 2 .Cl HOCl hn ? ClOO. .Cl
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