Semi-empirical model of collision-induced absorption spectra of H2-H2 complexes in the second overtone band of hydrogen at temperatures from 50 to 500 K

We present a semi-empirical numerical method to compute the binary collision-induced rotovibrational absorption spectra (RV CIA) of H-2-H-2 complexes in the second overtone band of hydrogen, at temperatures from 50 to 500 K, The spectral region of the second overtone corresponds approximately to similar to 0.86-0.77 mu m, and is often referred to as the (3-0) band. Model spectra closely reproduce recent two-body experimental CIA measurements (Brodbeck et al, 1999), The numerical procedure described in this paper uses simple analytical model lineshapes and can generate the RV CIA spectra of H2-H2 with simplicity, The lineshape parameters are based on the fit to experimental data, but their temperature dependence is imposed to agree with quantum mechanical theory (Fu et al. 1999). The FORTRAN program, utilizing the presented method, is available at http://www.astro.ku.dk/similar to aborysow/programs/. The program allows for a variation of the para-to-ortho hydrogen ratio, a feature that is very useful in planetary atmosphere studies. This work is of interest for modeling of the atmospheres of the outer planets, especially those of Neptune and Uranus, in the near-infrared region of the spectrum. (C) 2000 Academic Press.