Temperature dependences of air-broadening, air-narrowing and line-mixing coefficients of the methane ν3 R(6) manifold lines—Application to in-situ measurements of atmospheric methane

Mean age of stratospheric air derived from AirCore observations

“…In contrast to the Picarro G2401 used by the University of Frankfurt, the LMD team used a G2301 analyser, which lacks the capacity to measure CO. The payload also included two pico-SDLA spectrometers (Ghysels et al, 2014;Durry and Hauchecorne, 2005) for measurements of CO 2 and CH 4 , which are based on in situ infrared absorption measurements. Results from the latter measurements were perturbed due to thermal drifts in laser emission wavelength and are not available at the time of writing.…”

Intensities, broadening and narrowing parameters in the ν 3 band of methane

“…Identification and quantification of these lines in the spectrum are of considerable interest for the retrieval of CH 4 abundance in planetary atmosphere. Methane is the second most important greenhouse gas in Earth's atmosphere after CO 2 [3] and its abundance with the altitude in our atmosphere, monitored near 3.4 µm, has been recently reported in [4][5][6]. Methane is one of the important constituents detected in the atmosphere of Saturn [7][8][9], Titan [10][11][12][13][14][15][16], Jupiter [17][18], Uranus [19][20], Mars [21][22] and Pluto [23].…”

“…More recently, Ghysels et al [6] revised the R(6) manifold transitions of the ν 3 band of CH 4 using a difference-frequency-generation (DFG) laser near 3086 cm -1 with the purpose to monitor in-situ CH 4 in the middle atmosphere using the PicoSDLA-CH 4 spectrometer. The spectroscopic parameters of air-broadening, air-narrowing and line-mixing were measured for six lines of CH 4 at gas temperature between 213.5 and 296 K [6].…”

“…The spectroscopic parameters of air-broadening, air-narrowing and line-mixing were measured for six lines of CH 4 at gas temperature between 213.5 and 296 K [6]. A few other studies used difference-frequency-generation (DFG) techniques to report the detection of absorption lines in ambient air and spectroscopic parameters of CH 4 in the ν 3 band around 3.4 µm [32][33][34][35].…”

In situ measurements of methane in the troposphere and the stratosphere by the Ultra Light SpEctrometer Amulse

“…The used molecular model that takes into account line-mixing effect between some transitions of the selected multiplet is described in Ref. [24]. The concentration retrieval technique (Fig.…”