The calculation of the intrinsic radiation of atmosphere in the general circulation model of the lower and middle atmosphere of the Earth

This paper presents a description of the block of calculation of the intrinsic radiation of the Earth atmosphere in the IR range, which is developed for the model of the General circulation of the lower and middle atmosphere. This block uses a new parametrization of molecular absorption in the frequency range from 10 to 2000 cm$^{-1}$ in the height range from the Earth's surface to 76 km. The algorithm for constructing this parametrization takes into account the change in the gas composition of the atmosphere with height and has a number of other advantages. The results of the reference calculations of the field of natural radiation of the earth's atmosphere are compared with the results of calculations performed using parametrization, and it is shown that the presented parametrization has good accuracy in the lower and middle atmosphere in the absence of clouds, and in the presence of cloud layers with a large optical thickness.