A fast and accurate method of calculation of gaseous transmission functions in planetary atmospheres

A new method of calculation of atmospheric transmittance in planetary atmospheres is discussed. The gaseous absorption coefficient is represented as a product of two functions: k(p,T,ν) = G(p) · F(T,ν), where time consuming line-by-line calculations are involved in F(T,ν). They are performed only once on a specified temperature and wave number grid. This created matrix is then used for fast interpolative determination of the absorption coefficient at any atmospheric level. The behaviour of this algorithm is studied for both Lorentz and Voigt line profiles. Test calculations for the 15 μm CO2 band for the conditions typical for the Earth, Mars and Venus atmospheres are presented. This method combines speed and accuracy and can be effectively used in a wide range of atmospheric studies: thermal sounding, quantitative spectroscopy, radiative energy balance calculations.