ESTIMATION OF HEAT AND MASS FLUXES FROM IR BRIGHTNESS TEMPERATURE

Soil-vegetation-atmosphere transfer models have been developed to simu late mass and energy exchanges between vegetation canopies, the soil, and the atmosphere. They may be used in cunjunction with remote sensin g data through inversion procedures, In this study, the inversions of two soil-vegetation-atmosphere transfer models are compared on the sam e data set. Hourly evolutions of stomatal conductance and evapotranspi ration are retrieved from the midday measurement of thermal infrared b rightness temperature, Seasonal evolution of evapotranspiration and mi dday 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 evolutio n of stomatal conductance, and then underestimates morning and afterno on evapotranspiration. The other model gives a better description of h ourly evolutions of stomatal conductance and evapotranspiration. This model gives also better estimates of hourly canopy photosynthesis. How ever, it requires more parameters and computer time than the simpler m odel, typo unfavorable factors for inversion.