A mathematical model of interrelations between plant canopies and the atmospheric boundary layer was developed to quantify the influence of changes in soil moisture on the air temperature and humidity in the surface layer of the atmosphere. The verification of the model was carried out using experimental data concerning the maize canopy. It was shown that the soil moisture in the root zone is an important factor affecting not only the evapotranspiration but also the structure of the energy balance of plant canopies and consequently the air temperature and humidity in the surface layer of the atmosphere.
The values of the evapotranspiration calculated by the energy balance method were compared with corresponding results obtained by means of the EVASU model. Experimental data were obtained during NOPEX - First Concentrated Field Effort (CFE1). The CFE1 was realized in May-June 1994 in Lövsta, Sweden. The investigated vegetation were grass, spring barley, rye and winter wheat. Taking into account the accuracy of the both compared methods used for calculation of the evapotranspiration, the obtained results can be considered as very close in the interval of evapotranspiration rates between values 0.1 mm h⁻¹ and 0.5 mm h⁻¹.