Collision widths of CO lines broadened by water vapor at elevated temperatures

Introduction of Water‐Vapor Broadening Parameters and Their Temperature‐Dependent Exponents Into the HITRAN Database: Part I—CO2, N2O, CO, CH4, O2, NH3, and H2S

“…The third‐ to fourth‐order Padé approximant was applied to fit the data from both theoretical values and experimental results while constraints were made at very high rotational levels to avoid negative results during the fitting. Therefore all data reported in Deng et al (), Hartmann et al (), Henningsen et al (), Soufiani and Hartmann (), and Willis et al () were fitted with a least squares procedure to a Padé approximant (see equation ). The fitting resulted in the following coefficients: a 0 = 8.68258, a 1 = − 20.7531, a 2 = 12.83443, a 3 = − 0.08283, b 1 = − 95.99764, b 2 = 102.62357, b 3 = − 0.12397, b 4 = 0.0238.…”

“…γ H2O for CO lines. The magenta circle represents the broadening parameters for the R(11) transition in the fundamental band measured by (Deng et al, ); red triangles—the P(2), P(3), and P(7) transitions in the fundamental band are from (Willis et al, ); yellow square—the R(7) transition in the second overtone band by (Henningsen et al, ); green stars—measurements in the fundamental band from (Varghese & Hanson, ); and black circle—P(4) transition from (Soufiani & Hartmann, ). The blue triangles were scaled calculations from (Hartmann et al, ) and the red line corresponds to the fitting result of the third‐ to fourth‐order Padé approximant.…”

“…The water-vapor broadening parameters of carbon monoxide lines are needed for the high-accuracy trace gas retrieval missions (e.g., Clerbaux et al, 2008;Liu et al, 2011Liu et al, , 2014, and these parameters are also very useful in the study of exoplanets with substantial amounts of water vapor in the atmosphere (Konopacky et al, 2013). The water-vapor broadening coefficients of CO transitions in the fundamental band have been measured by Deng et al (2017), Soufiani and Hartmann (1987), Willis et al (1984), and Varghese and Hanson (1981). (Henningsen et al (1999) performed water-vapor broadening measurement for the R(7) transition in the 3-0 overtone band.…”

“…(b) The ratio of the water-vapor broadening half-widths of methane transitions to their corresponding air-broadening half-widths in HITRAN, as well as the average value of the those ratios plotted here. Deng et al (2017), Hartmann et al (1988), Henningsen et al (1999), Soufiani and Hartmann (1987), and Willis et al (1984) were fitted with a least squares procedure to a Padé approximant (see equation (4)). The fitting resulted in the following coefficients: a 0 = 8.68258, a 1 = − 20.7531, a 2 = 12.83443, a 3 = − 0.08283, b 1 = − 95.99764, b 2 = 102.62357, b 3 = − 0.12397,b 4 = 0.0238.…”

The Nonlinearity and Related Band Strength of Carbon Monoxide When Applied in Ambient Air Measurement Using Open Long-Path Fourier Transform Infrared Spectrometry

“…8,11 Based on these measurements, the integrated intensity of the fundamental CO band has been determined, and most of the values in recent years approach an average of ~221 atm -1 cm -2 at standard temperature and pressure (STP). This value is larger than the values obtained before the 1940s, when the pressurized method was used.…”