TY - JOUR
T1 - Remote sensing of methane with broadband laser and optical correlation spectroscopy on the Q-branch of the 2ν3 band
AU - Thomas, Benjamin
AU - David, Grégory
AU - Anselmo, Christophe
AU - Coillet, Elodie
AU - Rieth, Katja
AU - Miffre, Alain
AU - Cariou, Jean Pierre
AU - Rairoux, Patrick
N1 - Publisher Copyright:
© 2013 Elsevier Inc. All rights reserved.
PY - 2013
Y1 - 2013
N2 - With a global warming ability 72 times higher than carbon dioxide on short-term climatology, methane gas is one of the most important greenhouse gases in the Earth's atmosphere. After one decade of global constant value, the global methane concentration in the Earth's atmosphere is now increasing, so that methane monitoring is becoming a challenge, both at global and local scales. In this contribution, we propose a study on the ability to achieve accurate range-resolved methane concentration measurements in the Earth's atmosphere by combining broadband optical correlation spectroscopy (OCS) with lidar. Our study focuses on the 2ν3 methane absorption band, centered at the 1665 nm wavelength, which lies in an absorption infrared window of the Earth's atmosphere. A numerical study has been achieved to assess the influence of the methane absorption spectroscopic line parameters on the retrieved methane-mixing ratio when applying the OCS-lidar methodology. It is shown that an atmospheric temperature gradient induces a systematic error on the retrieved methane-mixing ratio, and this error is here accurately evaluated. Moreover, we show that methane-mixing ratios are weakly sensitive to the pressure broadening of the absorption line and to the statistical variation of the absorption line strength. The finding is that, thanks to accurate methane line parameters in the 2ν3 methane absorption band, an accurate remote sensing of methane-mixing ratio, in the tens of ppm range, can be achieved with OCS-lidar with only a weak constraint on the value of the temperature of the atmosphere.
AB - With a global warming ability 72 times higher than carbon dioxide on short-term climatology, methane gas is one of the most important greenhouse gases in the Earth's atmosphere. After one decade of global constant value, the global methane concentration in the Earth's atmosphere is now increasing, so that methane monitoring is becoming a challenge, both at global and local scales. In this contribution, we propose a study on the ability to achieve accurate range-resolved methane concentration measurements in the Earth's atmosphere by combining broadband optical correlation spectroscopy (OCS) with lidar. Our study focuses on the 2ν3 methane absorption band, centered at the 1665 nm wavelength, which lies in an absorption infrared window of the Earth's atmosphere. A numerical study has been achieved to assess the influence of the methane absorption spectroscopic line parameters on the retrieved methane-mixing ratio when applying the OCS-lidar methodology. It is shown that an atmospheric temperature gradient induces a systematic error on the retrieved methane-mixing ratio, and this error is here accurately evaluated. Moreover, we show that methane-mixing ratios are weakly sensitive to the pressure broadening of the absorption line and to the statistical variation of the absorption line strength. The finding is that, thanks to accurate methane line parameters in the 2ν3 methane absorption band, an accurate remote sensing of methane-mixing ratio, in the tens of ppm range, can be achieved with OCS-lidar with only a weak constraint on the value of the temperature of the atmosphere.
KW - Absorption line parameters
KW - Absorption spectroscopy
KW - Correlation
KW - Lidar
KW - Methane
KW - Mid-infrared
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U2 - 10.1016/j.jms.2013.05.015
DO - 10.1016/j.jms.2013.05.015
M3 - Article
AN - SCOPUS:84939458170
SN - 0022-2852
VL - 291
SP - 3
EP - 8
JO - Journal of Molecular Spectroscopy
JF - Journal of Molecular Spectroscopy
ER -