Study on the temperature dependence of oxygen A-band absorption coefficient

Abstract

Oxygen A-band is an ideal inversion channel. Absorption coefficient is one of the important parameters, its precision determines the accuracy of inversion result. The influence factor for the absorption of oxygen A-band is analyzed using HITRAN2012 database and temperature profiles of atmosphere. The temperature dependence is deduced for each influence factor, and then for the absorption coefficient. It is found that the influence of temperature on the coefficient is poor for HWHM (half width at half maximum) of the spectral line, but the HWHM of the line is greatly influenced by the temperature. The linetype function has two changes during the variation of temperature: The function value decreases with increasing temperature beyond the HWHM; it, however, slowly increases from the center frequency to HWHM of the line. The line intensity is strongly dependent on the temperature. Using the line by line integral algorithm, the absorption of oxygen A-band is calculated. The temperature dependences are considered to come from the pressure broadening effect, spectral line intensity, and HWHM. A conclusion is given that the temperature dependence of absorption of oxygen A-band comes from line intensity, and especially the center frequency. While, the temperature dependence of the linetype function with Lorentzian is not obvious. Finally, the absorption of oxygen A-band is measured at 63m using BRUKER spectrometer with 1 cm-1. The error is less than 0.83% as compared with that in theoretical model under the same condition. The correctness of the temperature calibration model is thus verified.