Estimation of heat and mass fluxes from IR brightness temperature

Abstract

Soil-vegetation-atmosphere transfer models have been developed to simulate mass and energy exchanges between vegetation canopies, the soil, and the atmosphere. They may be used in conjunction with remote sensing data through inversion procedures. In this study, the inversions of two soil-vegetation-atmosphere transfer models are compared on the same data set. Hourly evolutions of stomatal conductance and evapotranspiration are retrieved from the midday measurement of thermal infrared brightness temperature. Seasonal evolution of evapotranspiration and midday stomatal conductance are monitored with a good accuracy with both models. However, the simpler model underestimates evapotranspiration because it does not include a realistic description of hourly evolution of stomatal conductance, and then underestimates morning and afternoon evapotranspiration. The other model gives a better description of hourly evolutions of stomatal conductance and evapotranspiration. This model gives also better estimates of hourly canopy photosynthesis. However, it requires more parameters and computer time than the simpler model, two unfavorable factors for inversion.