In this study, we present an inverse calculation model to reconstruct time-averaged temperature, species concentration and their root mean square (rms) values from optical measurements for a homogeneous turbulent gaseous medium. The model is based on line-of-sight spectral transmissivity measurements, and time-averaged transmissivities and their rms values are successfully related to time-averaged temperatures, species concentrations and their rms values by considering interaction between turbulence and radiation (TRI). The turbulence length scale is also retrieved simultaneously with the turbulent scalars. In order to validate the model, a stochastic approach is used to generate synthetic turbulent fields (fluctuations of temperature and species concentration), and measured spectra are synthesized through calculations from HITEMP 2010 for different spectral bands of CO₂, H₂O and CO.