Deployment of the Regional Climate Model for the South of Russia Based on RegCM 4.5

We describe the first stage of the deployment of the regional climate model for Southern Russia based on RegCM 4.5, which requires updating a set of parameterization schemes for subgrid physical processes for the simulated region. Modeling the general circulation of the atmosphere requires a high rate of calculation of the radiation characteristics, which implies a high degree of parametrization of the radiation transfer equation, including the charac-teristics of molecular absorption. Molecular absorption has a high selectivity compared with aerosol and molecular scattering in the visible and infrared spectral range, which is a significant problem. The calculation schemes in the RegCM radiation block are described in detail. Our research has shown that the rows of exhibitors provide a high degree of parametrization and high accuracy of calculation comparable to the line-by-line method. Calculations of fluxes of long-wave radiation with different versions of the spectroscopic HITRAN database showed that the differences between the down-fluxes are less than 0.1 W/m2 at the lower atmosphere for summer in moderate latitudes, and fluxes upwards are not more than 0.6 W/m2 at the upper boundary of the atmosphere. The upstream value at the upper atmosphere is 281.01 W/m2 using the spectroscopic database HITRAN2012, and our estimate of the downward flux is 351.16 W/m2 . These results indicate that modern spectroscopic databases provide highly accurate calculation of broadband fluxes. To estimate the uncertainty in the radiation fluxes, we used the continuum absorption model for the vapor H2 O, which was used in the entire long-wavelength spectral range except the transparency window 830–1130 cm−1 , where we used our model based on experimental data. Initial and boundary conditions are determined from the European Center for Medium-Range Weather Forecast’s ERA-Interim global climate model (EIN 15), and Indian Ocean Sea Surface Temperature (IOSST) data are used to set sea surface temperatures. The verification phase includes analyzing the choice of the computing area, determining the accuracy of the vertical profiles of parameters, comparing temperature fields using observational data. We propose to analyze the spatial-temporal characteristics of specific meteorological events, first of all, heavy precipitation to assess the quality of regional climate models. This approach seems to be more reliable than the traditional consideration of temperature distributions.