Three-dimensional modeling of the O2(1Δ) dayglow and implications for ozone in the middle atmosphere. - INSU - Institut national des sciences de l'Univers Access content directly
Conference Papers Year : 2024

Three-dimensional modeling of the O2(1Δ) dayglow and implications for ozone in the middle atmosphere.

Mouhamadou Diouf
Franck Lefèvre
Alain Hauchecorne
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  • PersonId : 914935
Jean-Loup Bertaux
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  • PersonId : 914210

Abstract

Future space missions dedicated to measuring CO2 on a global scale can make advantageous use of the O2 band at 1.27 μm to retrieve the air column. The 1.27 μm band is close to the CO2 absorption bands at 1.6 and 2.0 μm, which allows a better transfer of the aerosol properties than with the usual O2 band at 0.76 μm. However, the 1.27 μm band is polluted by the spontaneous dayglow of the excited state O2(1Δ), which must be removed from the observed signal. We investigate here our quantitative understanding of the O2(1Δ) dayglow with a chemistry- transport model. We show that the previously reported -13% deficit in O2(1∆) dayglow calculated with the same model is essentially due a -20 to -30% ozone deficit between 45-60 km. We find that this ozone deficit is due to excessively high temperatures (+15 K) of the meteorological analyses used to drive the model in the mesosphere. The use of lower analyzed temperatures (ERA5), in better agreement with the observations, slows down the hydrogen-catalyzed and Chapman ozone loss cycles. This effect leads to an almost total elimination of the ozone and O2(1Δ) deficits in the lower mesosphere. Once integrated vertically to simulate a nadir measurement, the deficit in modeled O2(1Δ) brightness is reduced to -4±3%. This illustrates the need for accurate mesospheric temperatures for a priori estimations of the O2(1Δ) brightness in algorithms using the 1.27 μm band
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insu-04501100 , version 1 (03-06-2024)

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Mouhamadou Diouf, Franck Lefèvre, Alain Hauchecorne, Jean-Loup Bertaux. Three-dimensional modeling of the O2(1Δ) dayglow and implications for ozone in the middle atmosphere.. EGU General Assembly 2024, Apr 2024, Vienna and Online, Austria. pp.EGU24-1897, ⟨10.5194/egusphere-egu24-1897⟩. ⟨insu-04501100⟩
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