氧气A带吸收系数的温度依赖关系研究

氧气A带是理想的大气要素反演通道,吸收系数是重要的参数之一,它影响到反演结果的精度.结合HITRAN2012数据库和大气温度廓线图,分析氧气A带吸收系数的影响因素,推出各因素与温度的依赖关系,确定吸收系数随温度的变化.结果表明,氧气A带谱线半宽度受温度依赖系数影响较小,而受温度影响较大.线型因子随温度产生了两种变化,在谱线半宽度以外的谱线位置上,随温度的增大,函数值减小,而在中心频率到谱线半宽度的谱线位置上,随温度的升高而增大.谱线线强对温度具有强依赖关系.利用逐线积分算法计算氧气A带吸收系数,同时考虑了谱线半宽度的压力展宽效应和谱线线强及半宽度对温度的依赖关系,得出氧气A带吸收系数对温度的依赖关系主要来源于线强的温赖关系,尤其是中心频率处温度影响较大;而Lorentzian线型函数的温赖关系不明显.利用布鲁克光谱仪在1 cm-1下测量63 m处氧气A带的吸收光谱,与理论模型在同等条件下的透过率比较,误差小于0.83%,验证了温度校正模型的正确性.

Study on the temp erature dep endence of oxygen A-band absorption co efficient

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.
Keywords：oxygen A-bandabsorption coefficienttemperature dependenceline intensity