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| Titel |
Pressure broadening coefficients of HO2 for CO2 and Ar at 625.66GHz for Martian atmosphere |
| VerfasserIn |
Kota Kuribayashi, Asao Mizoguchi, Hideto Kanamori, Yasuko Kasai |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250080012
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| Zusammenfassung |
| Pressure broadening parameters are crucial to obtain the abundance of vertical profile of the
atmospheric composition from spectroscopic remote sensing observations.
We determined the pressure broadening coefficients of the perhydroxyl (HO2) radical for
the carbon dioxide (CO2) and the argon (Ar) respectively at the pure rotational transition at
625.66Â GHz (NKaKc = 1019 - 10010, J = 10.5 - 10.5) in the vibronic ground state X2A′ by
laboratory measurements. For the production of HO2, the mercury-photosensitized reaction
of the H2 and O2 precursors was used to provide an optimum condition for measurements of
the pressure broadening coefficients. The measurements were carried out using a
submillimeter-wave spectrometer that employs a backward wave oscillator (BWO) as the
radiation source. Coefficients of pressure broadening for CO2 and Ar at room temperature are
determined by a convolution method. In this work, measurements were performed at
room temperature as γ(CO2) = 7.457 ± 0.087 (3Ïă) and γ(Ar) = 2.193 ± 0.021 (3Ïă)
MHz/Torr.
The Martian atmosphere pressure broadening coefficient, γ(Mars), can be estimated from
γ(CO2), γ(N2), and γ(Ar) as γ(Mars) = γ(CO2) à 0.955 + γ(N2) à 0.027 + γ(Ar) Ã
0.016, where 0.955, 0.027, and 0.016 are the fractions of CO2, N2, and Ar in the
Martian atmosphere. The Martian atmosphere broadening coefficient is estimated as
γ(Mars) = 7.267 ± 0.085 (3Ïă) MHz/Torr at room temperature. The air-pressure
broadening coefficient of the 625.66Â GHz transition at room temperature was reported
as γ(air) = 3.769 ± 0.067 (3Ïă) MHz/Torr (Mizoguchi et al, 2012). The ratio of
γ(air) and γ(Mars) of HO2 is 1.93, and this is larger than averaging one of γ(air)
and γ(CO2) of HO2 measured by Sagawa et al. (2009). The large ratio of HO2
might cause the serious different of the abundance of the vertical profile in Martian
atmosphere.
We plan to make a comparison of the spectrum simulated by the line-by-line radiative
transfer calculations using our estimated pressure broadening coefficient of Martian
atmosphere and the AMATERASU (Advanced Model for Atmospheric Terahertz Radiation
Analysis and Simulation, Baron et al., 2008) forward model. |
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