CO2-broadening coefficients in the ν4 fundamental band of methane at room temperature and application to CO2-rich planetary atmospheres

Machine learning for automatic identification of new minor species

“…To construct the simulated transmittance spectra, the high resolution irradiances were computed for each occultation assuming a spherically symmetry and the tangent atmosphere developed from GEM-Mars for several different abundance of methane and water, which were simulated as constant volume mixing ratios. The spectroscopic data for methane and water were taking from HITRAN 2016 using CO 2 broadening (Gordon et al, 2017;Gamache et al, 2016;Fissiaux et al, 2014…”

Recent advances in collisional effects on spectra of molecular gases and their practical consequences

“…This molecule might be present at the parts-per-billion level and detecting it requires highly sensitive observations at high spectral resolution together with very accurate spectroscopic parameters. This has motivated several studies to derive CO 2 -broadening line widths and LM effects in CH 4 to prepare for upcoming observations (eg [453,454,501]). Despite the low surface pressure on Mars (600 Pa on average), LM effects are visible in CH 4 spectra at the spectral resolution of the NOMAD spectrometer (0.1 cm -1 ) onboard ExoMars Trace Gas Orbiter [453] and they will be taken into account.…”

“…This has motivated several studies to derive CO 2 -broadening line widths and LM effects in CH 4 to prepare for upcoming observations (eg [453,454,501]). Despite the low surface pressure on Mars (600 Pa on average), LM effects are visible in CH 4 spectra at the spectral resolution of the NOMAD spectrometer (0.1 cm -1 ) onboard ExoMars Trace Gas Orbiter [453] and they will be taken into account. Finally, since temperatures on Mars span the 150-290 K range, correct modeling of the effects of collisions with CO 2 on individual lines and manifolds of all relevant absorbing species is needed below room temperature.…”

High-temperature measurements of methane and acetylene using quantum cascade laser absorption near 8 μm

“…The spectroscopic region near 8 μm has been investigated in several studies to determine linestrengths, self-and foreign-gas broadening coefficients and their temperature dependent exponents for the ν 4 band of methane [39][40][41][42] and the ν 4 þν 5 band of acetylene [43][44][45][46][47][48][49]. Most of these studies were performed near or below room temperature with relevance to atmospheric and astrophysical applications.…”

“…Using diode-laser spectrometer, self-broadening coefficients of 42 lines in the ν 4 band of methane were reported by Lepère [41]. CO 2 -broadening coefficients of 28 lines in the ν 4 band of methane were measured at room temperature by Fissiaux et al [39]. For ν 4 band of 13 CH 4 , the N 2 -and O 2 -broadening coefficients and the temperature dependent exponents were reported for 11 and 10 lines, respectively, by performing measurements in the temperature range of 173-273 K [42].…”