Simulated exoplanet transmission spectra are critical for planning and interpretation of observations and to explore the sensitivity of spectral features to atmospheric thermochemical processes .
We present a publicly available generic model grid of planetary transmission spectra , scalable to a wide range of H _ { 2 } /He dominated atmospheres .
The grid is computed using the 1D/2D atmosphere model ATMO for two different chemical scenarios , first considering local condensation only , secondly considering global condensation and removal of species from the atmospheric column ( rainout ) .
The entire grid consists of 56,320 model simulations across 22 equilibrium temperatures ( 400 - 2600 K ) , four planetary gravities ( 5 - 50 ms ^ { -2 } ) , five atmospheric metallicities ( 1x - 200x ) , four C/O ratios ( 0.35 - 1.0 ) , four scattering haze parameters , four uniform cloud parameters , and two chemical scenarios .
We derive scaling equations which can be used with this grid , for a wide range of planet-star combinations .
We validate this grid by comparing it with other model transmission spectra available in the literature .
We highlight some of the important findings , such as the rise of SO _ { 2 } features at 100x solar metallicity , differences in spectral features at high C/O ratios between two condensation approaches , the importance of VO features without TiO to constrain the limb temperature and features of TiO/VO both , to constrain the condensation processes .
Finally , this generic grid can be used to plan future observations using the HST , VLT , JWST and various other telescopes .
The fine variation of parameters in the grid also allows it to be incorporated in a retrieval framework , with various machine learning techniques .