The mathematical model of land surface consisting of the layer of vegetation and the upper layer of soil is described. The scheme of land surface-atmosphere interaction is based on the transformation of heat and moisture fluxes which allows the use of a small number of parameters. The model is coupled with Global Climate model of the Computing Center of the Russian Academy of Sciences. The results of test investigations using $5^\circ\times 4^\circ$ и $1^\circ\times 1^\circ$ latitude-longitude grid resolution are compared.