Evaporation from sparse crops‐an energy combination theory

TLDR

A one‑dimensional model is used to describe energy partition in sparse crops, and further studies are needed to apply the equation to seasonal evaporation. The model derives a combination equation that expresses evaporation in terms of plant, soil, and water resistances. The equation yields a simple, physically plausible description of the transition from bare substrate to closed canopy, and shows that typical aerodynamic transfer resistance values for incomplete canopies have limited impact on the model despite lacking experimental validation.

Abstract

Abstract A one‐dimensional model is adopted to describe the energy partition of sparse crops. Theoretical development of this model yields a combination equation which describes evaporation in terms of controlling resistances associated with the plants, and with the soil or water in which they are growing. the equation provides a simple but physically plausible description of the transition between bare substrate and a closed canopy. Although the aerodynamic transfer resistances for incomplete canopies have, as yet, no experimental justification, typical values, appropriate to a specimen agricultural crop and soil, are shown to have limited sensitivity in the model. Processes which require further study if the equation is to be used to calculate evaporation throughout a crop season are also discussed.