Diurnal variation of oxygen isotopic enrichment in asymmetric‐18 ozone observed by the SMILES from space

Atomic oxygen is a key oxidant for greenhouse gases such as H 2 O, CH 4 , and N 2 O whose amounts are currently increasing in the stratosphere. Ozone photolysis is a major source of atomic oxygen generation. We found, for the first time, that the ozone photolysis of 48 O 3 and 18 O 16 O 16 O generat...

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Bibliographic Details
Published in:Geophysical research letters 2017-06, Vol.44 (12), p.6399-6406
Main Authors: Sato, T. O., Kuribayashi, K., Yoshida, N., Kasai, Y.
Format: Article
Language:English
Subjects:
Air pollution
Asymmetry
Atmospheric chemistry
Atomic oxygen
Chemistry
Daytime
Diurnal variations
Fractionation
Gases
Greenhouse effect
Greenhouse gases
Isotope fractionation
Isotopes
Isotopic enrichment
Middle stratosphere
Night
Nitrous oxide
Oxidizing agents
Oxygen
Oxygen enrichment
Ozone
Ozone formation
Photolysis
Radiation
Solar radiation
Stratosphere
Superconductivity
Temporal variations
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Summary:Atomic oxygen is a key oxidant for greenhouse gases such as H 2 O, CH 4 , and N 2 O whose amounts are currently increasing in the stratosphere. Ozone photolysis is a major source of atomic oxygen generation. We found, for the first time, that the ozone photolysis of 48 O 3 and 18 O 16 O 16 O generated a sharp diurnal variation of δ 18 OOO in the middle stratosphere (37 km), in contrast to the temporal variation of 48 O 3 . The average isotopic enrichment δ 18 OOO derived from the Superconducting Submillimeter‐Wave Limb‐Emission Sounder (SMILES) observation was higher during daytime (16.2 ± 3.3%) than at night (13.7 ± 3.6%). Isotopic fractionation effects were simulated for both ozone formation reaction and ozone photolysis with the ozone photolysis contribution estimated to be 80% of the daytime δ 18 OOO enhancement. Significant solar radiation dependence was observed in the isotopic fractionation of ozone photolysis derived from the SMILES observation and theoretical calculations. These results show that δ 18 O can be a powerful tool to investigate oxidant chemistry. Diurnal variation of the oxygen isotopic ratio of asymmetric‐18 ozone ( δ 18 OOO) was derived from spaceborne SMILES observation for the first time The δ 18 OOO diurnal behavior was observed to be different from those of 48 O 3 and 18 O 16 O 16 O concentrations Significant solar radiation dependence was observed in the isotopic fractionation of ozone photolysis derived from our analysis
ISSN:0094-8276
1944-8007
DOI:10.1002/2016GL071924