The Study On Temperature Dependence Of The Atmospheric Gases Absorption

Temperature dependence of the atmospheric gases absorption is very important for improving the gas absorption calculation speed and establishing actual atmospheric radiative transfer model.Using HITRAN 2004,the updated molecular spectroscopic database,and an exact line-by-line algorithm,we take CO₂ 15μm absorption band as an example to discuss the temperature dependence of half width, the line intensity and absorption coefficient.On this basis,several approaches are considered to determine the temperature effect on the absorption coefficient and it is emphasized by numerical calculations.The main results are as follows:1.In the case of 15μm absorption band,it is found that temperature dependence of the absorption coefficient is mainly affected by the line intensity while the half-width effect is not very important.On the other hand,temperature dependence of line intensity is mainly affected by exp[1.439E"(T-T₀)/(T×T₀)]while the total partition function effect is not very important.2.The line intensity and then the absorption coefficient depend strongly on temperature in the wings of band,by contraries the dependence is relatively weak in the center of band.3.At present,the approaches for the effect of temperature on the absorption coefficients are still in the stage of numerical test.The accuracy of different methods is not only concerned with absorption gas and its absorption band but also affected by the different high-level atmosphere.4.Although temperature effects on the absorption coefficient are of secondary importance compared with pressure effects,numerical results indicate that its effect must be considered in actual radiative calculations taking into account the complexity of its impact on infrared radiative calculations.