Measurements of N2- and O2-broadening and shifting parameters of methane spectral lines in the 5550–6236cm−1 region

Preliminary validation of column-averaged volume mixing ratios of carbon dioxide and methane retrieved from GOSAT short-wavelength infrared spectra

“…It may result from unknown spectroscopic parameters of O 2 and CO 2 or error in the TANSO-FTS calibration. In the case of the GOSAT SWIR data of X CH 4 , the negative bias decreased in the Ver.01.xx compared with the earlier Ver.00.yy when the spectroscopic parameters were changed from Lyulin et al (2009) to HITRAN 2008database (Rothman et al, 2009). Therefore it is important to further examine the spectroscopic parameters of O 2 , CO 2 and CH 4 .…”

The HITRAN2012 molecular spectroscopic database

“…For the pentad, about 500 prior measurements [138] were used along with approximately 3800 predicted values for γ air , n, and δ of the ν 3 transitions from Antony et al [142]. Scaled N 2 -broadening from Frankenberg et al [132] were inserted from 5860 to 6184 cm -1 and a few hundred values for γ air , were entered between 5560 to 5860 cm -1 [143]. The value for the parameter n was set either to a default constant (0.75 below 5860 cm -1 or 0.85 above 5860 cm -1 ) unless direct measurements were available (Lyulin et al [143]).…”

“…Scaled N 2 -broadening from Frankenberg et al [132] were inserted from 5860 to 6184 cm -1 and a few hundred values for γ air , were entered between 5560 to 5860 cm -1 [143]. The value for the parameter n was set either to a default constant (0.75 below 5860 cm -1 or 0.85 above 5860 cm -1 ) unless direct measurements were available (Lyulin et al [143]). …”

“…There are a number of ongoing and recent studies [143,144] which can further improve the near-IR parameters (4800 to 7700 cm -1 ). It is expected that an interim update of this region and a new semi-empirical list of the octad will be available within one year.…”

Line broadening coefficient calculations for methane perturbed by nitrogen

“…The subject of infrared line shapes studies for methane is extensively documented from an experimental point of view. Some of the most recent works dealt with measurements in the first four polyads of methane (dyad near 1300 cm −1 , pentad near 3000 cm −1 , octad near 4300 cm −1 and tetradecad near 6000 cm −1 ) [31][32][33][34][35][36][37][38][39][40][41][42][43]. We note that the temperature dependencies of line shape parameters and/or line mixing parameters could be determined in some of these studies.…”