Modelling temperatures of crop environment

Abstract

A model for calculating the crop environment temperatures (soil surface temperature, crop air space temperature and crop foliage temperature) for ecological modelling is presented. The crop foliage temperature and soil surface temperatures are calculated numerically from the system of two equations that represent the partitioning of energy over the crop canopy and its bare fraction. The crop air space temperature is determined diagnostically from the equality of the canopy's sensible heat flux to some reference level in the atmosphere and the sum of sensible heat flux from the soil surface and from the leaves to the canopy air volume. Parameterization of terms included in the equations provides a reliability in prediction of crop environment temperatures, particularly in the case of the sparsely distributed crop. The model is described through detailed consideration of: (1) calculations of turbulent fluxes, (2) the shape of the wind and turbulent transfer coefficient profiles, and (3) calculation of the aerodynamic resistances inside crop canopies. The proposed model is assessed using data measured in soybean, maize and sunflower canopies. Model outputs of crop environment temperatures are compared with micrometeorological measurements in soybean, sunflower and maize fields.