Evapotranspiration in forests was studied using a new method based on the Bowen ratio concept. By analyzing heat fluxes, researchers estimated actual evapotranspiration using air temperature and humidity at a single height. The method was validated using observed data from five sites worldwide. The study found that the new method accurately estimated latent and sensible heat fluxes at the canopy surface, correcting for heat imbalances. The temporal changes in heat fluxes were clarified using hourly and yearly data, and the estimated evapotranspiration values matched well with observed values.