Simulation of the Temperature, Humidity and Evaporation Profiles in a Leaf Canopy

Abstract

{T}he proposed model synthesizes profiles of temperature, humidity and evaporation in a canopy of leaves from meteorological conditions at canopy top, from the temperature and humidity at the soil surface, from a leaf dimension, from the vertical distribution of leaf area and stomatal resistance, and from observations or extinction coefficients for ventilation and radiation within the canopy under steady-state conditions. {T}he exchange of sensible and latent heat in a canopy stratum is required to be equal to the absorption of radiation by the leaves in that stratum. {F}urther, the difference between strata in their potential for sensible and latent heat exchange is related both to leaf temperature and to the fluxes and diffusive resistances between the leaves. {L}eaf temperatures, evaporation and sensible heat exchange, and air temperatures within the canopy that meet these requirements were calculated by successive approximation. {T}he microclimate and evaporation of a red clover and of a barley canopy were simulated, and changes in evaporation from a canopy following moderate changes in stomatal resistance were explained by the model.