This model applies an energy balance on the canopy. The energy balance is done by taking into account:
Since the short-wave radiation can origin from two sources (the sun and supplementary illumination), the short-wave radiation input connector (i.e. HeatFluxVectorInput) has the form of a vector. The parameter N_rad defines the dimension of the vector and needs to be set by the user. Therefore, if there is no supplementary lighting, the user must set N_rad to 1 (i.e. radiation only form the sun). However, if there is supplementary lighting, the user must set N_rad to 2 (i.e. radiatio from sun + lighting).
The magnitude of the energy exchanged by the canopy depends on the size of the leaves, which is increased by crop growth and decreased by leaf pruining. To take this into account, the leaf area index (LAI), defined as the leaf area per unit of ground area, is used. The LAI is computed in the crop yield model and input in this model.
The vapor pressure of water at the canopy is defined by the saturated vapor pressure for its temperature.