Calculation of the solar radiation field in the general circulation model of the Earth's lower and middle atmosphere

The results of testing two radiation blocks used for economical calculation of radiation transfer in the general circulation model of the lower and middle atmosphere of the Earth are presented. The first block is designed to calculate the field of intrinsic radiation in the frequency range from 10 to 3000 cm$^{-1}$, and the second block is designed to calculate the field of solar radiation in the frequency range from 2000 to 50,000 cm$^{-1}$. Each of these blocks uses its own parameterization of the optical parameters of the air in the altitude range from the Earth's surface to 90 km. When constructing these parameterizations, the change in the gas composition of the atmosphere with altitude was taken into account. For the numerical solution of the radiation transfer equation, the method of discrete ordinates is used. The results of calculations performed using the radiation block of the model are compared with the results of line-by-line calculations of the solar radiation field in the lower and middle atmosphere of the Earth, performed with a very high frequency resolution. It is shown that the model block provides good accuracy of calculations both in the absence of clouds and in the presence of cloud layers with a large optical thickness.